Findings from a Swedish national cohort study

Children and Youth Services Review 35 (2013) 1954–1961

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Alcohol and drug abuse among young adults who grew up in substitute care — Findings from a Swedish national cohort study☆ Annika von Borczyskowski a,b, Bo Vinnerljung c,⁎, Anders Hjern a,d a

Centre for Health Equity Studies (CHESS), Stockholm University, 106 91 Stockholm, Sweden Karolinska Institute, Stockholm, Sweden Department of Social Work, Stockholm University, S 106 91 Stockholm, Sweden d Clinical Epidemiology, Department of Medicine, Karolinska Institutet, Stockholm, Sweden b c

a r t i c l e

i n f o

Article history: Received 20 May 2013 Received in revised form 30 September 2013 Accepted 30 September 2013 Available online 9 October 2013 Keywords: Foster care Adoption Substance abuse Cohort study Longitudinal, Intergenerational transmission Siblings

a b s t r a c t To what extent substitute long term care modifies intergenerational transmission of substance abuse has rarely been investigated. Using register data, we followed a national cohort born 1973–1985 consisting of 1012 national adoptees, 2408 former children from long term foster care, 348/846 environmental siblings of adoptees/foster children, and 952,935 majority population peers, from their 15th birthday to age 27–35. Using Cox regression, we calculated hazard ratios (HR) for hospital care and criminality associated with illicit drug/alcohol abuse, with adjustments for socio-demographic indicators of caring families, and substance abuse in caring and birth parents. Among 37% of foster children, 9% of adoptees, and 1% of majority population peers, both birth parents had indications of substance abuse. In age/sex adjusted models foster children had four to sevenfold elevated HR for substance abuse outcomes, and adoptees two to threefold HR, in comparison with majority population peers. Estimates were only marginally attenuated after adjustments for socio-demographic indicators and morbidity of caring parents. After adjustments for birth parental substance abuse, HR decreased to around 1.5 for adoptees and foster children equally. Biological children of substitute parents did not differ substantially from majority population peers. © 2013 The Authors. Published by Elsevier Ltd. All rights reserved.

1. Introduction Alcohol abuse ranks third among the leading risk factors for the global burden of disease (Lim et al., 2012) and, together with drug abuse, is linked to educational underachievement, antisocial behavior and mental health problems as well as criminality in adulthood (Arteaga, Chen, & Reynolds, 2010). In general, substance abuse rates tend to be higher among men than women (Brady & Randall, 1999; Nolen-Hoeksema, 2004; Nolen-Hoeksema & Hilt, 2006), but recent studies point towards a closing gender gap concerning alcohol abuse and dependence (Keyes, Grant, & Hasin, 2008; Keyes, Li, & Hasin, 2011; Wilsnack, Wilsnack, Kristjanson, Vogeltanz-Holm, & Gmel, 2009). There have also been indications that family environment has a greater influence on girls than on boys regarding drug use (Block, Block, & Keyes, 1988). Adverse childhood experiences, such as abuse and neglect, but also single parenthood and divorce as well as parental substance abuse ☆ This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial-No Derivative Works License, which permits non-commercial use, distribution, and reproduction in any medium, provided the original author and source are credited. ⁎ Corresponding author. Tel.: +46 8 674 7048. E-mail addresses: [email protected] (A. von Borczyskowski), [email protected] (B. Vinnerljung), [email protected] (A. Hjern).

increase the risk of substance abuse in adulthood (Bennett & Kemper, 1994; Connell, Bergeron, Katz, Saunders, & Tebes, 2007; Hawkins, Catalano, & Miller, 1992; Osler, Nordentoft, & Andersen, 2006). These risk factors often accumulate in children that enter the child welfare system (Aarons et al., 2008; Dube et al., 2003; Simms, 1991; Takayama, Wolfe, & Coulter, 1998). In fact, for decades parental substance abuse has been a dominating or contributing factor for young children entering substitute care in Scandinavia (Andersson, 1991; Christoffersen & Soothill, 2003; Vinnerljung, 1996a; cp. Magura & Laudet, 1996). Placements of children of addicts tend to last longer than average foster care placements, and these children also experience a greater number of placements (Barth, Gibbons, & Guo, 2006; Connell et al., 2007; Rushton, 2004; Vanderploeg et al., 2007; Vinnerljung, 1996a). There is substantial evidence that substance abuse in parents increases the risk of substance abuse in their offspring (e.g., Hawkins et al., 1992; Tyrfingsson et al., 2010). The mechanisms involved are assumed to be strongly influenced by genetic factors. Adoption studies have been one prominent pathway for testing this hypothesis, also in a Swedish context (e.g., Bohman, 1978; Cadoret, Cain, & Grove, 1980; Cadoret, Troughton, O'Gorman, & Heywood, 1986; Cadoret, Yates, Troughton, Woodworth, & Stewart, 1995; Cloninger, Bohman, & Sigvardsson, 1981; Goodwin, Schulsinger, Hermansen, Guze, & Winokur, 1973, Goodwin et al., 1974; Kendler et al., 2012;

0190-7409/$ – see front matter © 2013 The Authors. Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.childyouth.2013.09.024

A. von Borczyskowski et al. / Children and Youth Services Review 35 (2013) 1954–1961

Sigvardsson, Cloninger, & Bohman, 1996; reviews in Hopfer, Crowley, & Hewitt, 2003; Johnson & Leff, 1999). Several studies have demonstrated that children growing up in Scandinavian substitute care have elevated risks of developing problems associated with alcohol and illicit drug abuse, compared to other peers (Berlin, Bohman & Sigvardsson, 1980a; Christoffersen & Soothill, 2003; Vinnerljung & Hjern, 2011; Vinnerljung, Berlin, & Hjern, 2010). There is partly contradictory empirical evidence concerning the strength of the intergenerational protective effect of substitute care. Generally, results from a host of longitudinal studies suggest that such effects tend to be stronger for adoption than for long-term foster care (e.g., Berlin, Vinnerljung, & Hjern, 2011; Bohman, 1971; Bohman & Sigvardsson, 1980a; Fergusson, Lynskey, & Horwood, 1995; Goodwin et al., 1974; Vinnerljung et al., 2010; reviews in Christoffersen, 2012; Christoffersen, Hammen, Andersen, & Jeldtoft, 2007). In a recent US study of 827 children, Traube, James, Zhang, and Landsverk (2012) found that being placed in foster care was a risk factor, rather than a protective factor, for substance abuse, and that avoiding foster care placement in child welfare was even a protective factor for future illicit drug abuse (Traube et al., 2012). As far as we know, comparative studies of long term foster care's and adoption's influence on intergenerational transmissions of risk for substance abuse are essentially absent in the literature, especially analyses that take selection factors into account (cp. Bohman & Sigvardsson, 1980a). In Scandinavia, substitute care was for decades used as an intervention for breaking assumed cycles of substance abuse by providing children of addicts with a new family environment (e.g., Bohman, 1995; Vinnerljung, 1996b). An almost deterministic theory of intergenerational transmission of a “social heritage” was instrumental for the interventionist oriented Swedish child welfare practice after WWII (Cederblad, 1998; Johnson, 1967, 1969, 1971; Vinnerljung, 1996b, 1998). Swedish child welfare legislation has never required substantiations of neglect or abuse as causes of interventions, but has had a focus on “parental unsuitability”. Through case worker interviews, Gunvor Andersson (1991) scrutinized decision processes for 189 Swedish children ages 0–3, born in the mid-1980, who were reported to seven local child welfare authorities. She found less than a handful of cases of suspected child abuse, more that were related to neglect, but the dominating reason for placing a child in out-of-home care was parental unacceptable lifestyle/behavior, mostly indicated by substance abuse (often in combination with partner violence and welfare dependency; cp. Franzén, Vinnerljung, & Hjern, 2008). A common case worker assessment was “…the home environment is characterized by substance abuse” (Andersson, 1991; p 50, authors' translation). Furthermore, Andersson found that in cases of parental substance abuse leading to out-of-home care, the parent–child relation was usually described as positive or normal in assessments from e.g., child psychiatric clinics. But the family situation characterized by parental substance abuse was decisive in itself. Only a selective minority of all Swedish children growing up with one or two substance abusing parents have been and will be removed from their home by child welfare authorities. As long as parents do not subject their children to visible neglect and abuse (very few do), exposure to social control authorities seems to be an important “risk factor” for child removal. Welfare dependency will keep the family in continuous contact with the same local authority that is responsible for child welfare, albeit another section (Franzén et al., 2008). Police arrests due to e.g., partner violence will cause a child welfare investigation, possibly leading to child removal (e.g., Andersson, 1991). Substance abusing parents who keep their jobs, stay out of trouble with law enforcement, and manage to stay under the radar of mandatory reporting from professionals (most do) will rarely have their parental custody challenged by society. In this study we investigated to what extent the increased risk of substance abuse among young adults who grew up in substitute care — a subgroup of all children with substance abusing birth parents —

1955

is associated with birth parental addiction and other psychiatric problems. We also examined the influence of exposure to such problems in the substitute family environment (cp. Sigvardsson et al., 1996), using children of the adoptive/foster parents as comparison groups. Finally, we compared the outcomes of long term foster care with adoption, taking into account indicators of psychiatric and addictive morbidity in birth parents as well as in substitute/caring parents. Our sample consists of individuals born 1973–1985, the tail-end being the same birth year cohorts as Andersson's (1991) sample. Earlier studies suggest that parental substance abuse was an even more decisive factor for child welfare interventions targeting the older segments of our cohort (Vinnerljung, 1996a,b). 2. Method We conducted a population-based cohort study using data from national registers. Sweden has a long tradition of national registers with high quality data for health and socioeconomic indicators. These registers are based on the individually unique 10-digit personal identification number (PIN) that follows every Swedish resident from birth (or time of immigration) to death. Different registers can be linked through the PIN (which in this dataset has been replaced with a randomized control number, identical for all utilized national registers). Also, members of the same birth/adoptive family can be identified and linked through a ‘Multi-Generation Register’, administered by Statistics Sweden. 2.1. Study population The study population consisted of the 957,549 individuals, born in Sweden between 1973 and 1985, who were alive and residents in Sweden at 15 years of age. Participants were followed from age 15 until 2008 (27–35 years of age). Five mutually exclusive study groups were identified in the study population: a) 1 012 (national) adoptees, b) 2408 foster children, c) 348 siblings to national adoptees (biological children of the adoptive parents), d) 846 siblings to foster children (biological children of the foster parents), and e) a majority population comparison group of 952,935 peers. National adoptees were identified in the Multi-Generation register. Adoptions by a step parent were excluded. The adoptees were all initially placed in out-of home care (foster family or residential care) before age 7, usually in a transitory phase lasting 1–3 months. The exact date of adoption is not available in the national registers, but from other sources we have information that approximately 80% were adopted before their first birthday (e.g., Nordlöf, 2001). Foster children were identified through the Child Welfare Intervention Register (administered by the National Board of Health and Welfare). They had been taken into foster care before their 12th birthday and had records for being in foster care for at least 5 years before their 18th birthday (long term care). Their mean time in out-of-home care was 12 years, the overwhelming part in foster family care. Cohort members in the foster care group also had to fulfill the criteria of living in a household other than any of their birth parents', in the censuses 1985 or 1990 (held by Statistics Sweden). For those born 1973–1978, the 1985 Census was used (at ages 7–12), for those born 1979–1985 the 1990 Census (at ages 5–11). Among all long term care foster children, 62.8% fulfilled the Census record criteria (n = 2 408). Their birth parental characteristics differed little from those that were recorded as living with at least one of their parents in the censuses (e.g., 35.7% vs. 36.7% had two birth parents with indications of substance abuse). There are several reasons for long term care foster children being recorded in the censuses as living with at least one birth parent: a) they had been in long term care but had returned home b) they came into care after the census c) they had more than one spell of out-of-home care and were at the time of the census residing with one or both birth parents. Siblings to foster children and adoptees were defined as biological children of the caring parents and living in the same household,

1956


according to information in the censuses of 1985 and 1990, and the Multi-generation Register. Subjects with contradictory data regarding study group classification were excluded from the analyses, mainly a small group that was classified as both national adoptees and long term foster children. We also found a few foster children recorded as living in two households at the time of the census, one that included a birth parent. These cases were also excluded. 2.2. Outcome variables Alcohol and illicit drug abuse were each separated into two sub categories, thus creating four outcome variables. All were defined as binary outcomes (yes/no). 1a) Alcohol related hospitalization included data from the National Patient Discharge Register on hospitalizations (1973–2008; administered by the National Board of Health and Welfare) with a main or contributory diagnosis associated with alcohol abuse, according to ICD-9 and 10 classification codes in the register. Alcohol related medical diagnoses that did not necessarily imply long-term alcohol abuse, such as alcohol intoxication, were not included. 1b) Information on Alcohol related criminality was retrieved from the Register of Court Convictions (administered by the National Crime Prevention Council), and was restricted to a conviction for driving while intoxicated. 2a) Drug related hospital treatment was identified in the National Hospital Discharge Register and included a main or contributory diagnosis associated with illicit drug abuse, according to ICD-9 and 10 classification codes. Also for this category, cases of only intoxication as indicator of drug abuse were not included. 2b) Drug related criminality was defined as conviction of a drugrelated crime, according to the Register of Court Convictions (possession, distribution or smuggling of illicit drugs).

Sweden): sex, year of birth, area of residency, and parental civil status. Data about household socioeconomic circumstances were retrieved from the 1985 and 1990 censuses. For the cohort born 1973–1978, the 1985 Census was used, for those born 1979–1985, the 1990 Census. The socioeconomic index (SEI) developed by Statistics Sweden was utilized as a well–recognized and frequently used measure, reflecting both level of education and position in the working place (Statistics Sweden, 2012). We used a classification with six socioeconomic groups: three levels of non-manual professionals, two levels of manual workers, and lastly a “miscellaneous group” that included farmers, self-employed, unemployed, students, homemakers, persons with full time disability pensions, and unclassified individuals. Childhood SES was defined as the highest SES of any adult in the household. 2.5. Statistical analysis Cox regression of person time was used to analyze hazard ratios for the four outcomes defined above for the foster children, adoptees, and the two sibling groups, in comparison with majority of population peers. Person time was calculated from age 15 until first event for each outcome, death, record of emigration, or end of follow-up in 2008. All analyses were performed with SPSS 20. Four different Cox regression models were used in the analyses. In Model I we adjusted for sex and age as a four-category variable (see Tables 1–2). Socio-demographic characteristics of the caring family (residency, single parent household and SES) were added in Model II. Model III was adjusted for all variables of Model II and additionally for caring mothers' and caring fathers' alcohol abuse, drug abuse and psychiatric illness. Model IV included the same socio-demographic indicators as Model III, but replaced the variables of the caring parents in Model III with birth parental indicators of alcohol abuse, drug abuse and psychiatric illness, separately for the birth mother and the birth father. Interaction analyses of gender were made in Model 1.

2.3. Parental confounders

3. Results

Swedish longitudinal national cohort studies have found that parental substance abuse and psychiatric morbidity independently of each other increase the risk of substance abuse in off-spring, even after controlling for the powerful predictor of school failure (Gauffin, Vinnerljung, Fridell, Hesse, & Hjern, 2013). This is also valid for children who grow up in long term foster care or become adopted (Berlin et al., 2011; Vinnerljung et al., 2010). Subsequently, indicators for parental risk indicators such as alcohol and/or drug abuse as well as psychiatric disorders were retrieved from the Cause of Death Register (held by the National Board of Health and Welfare), the National Patient Discharge Register, and the Register of Court Convictions. All parental indicators were analyzed for mothers and fathers separately, were treated as binary variables (yes/no), and defined by at least one recorded incident during 1973–2008. Parental alcohol and/or drug abuse was indicated by any entry of alcohol and/or drug related death, criminality or hospital care. Parental psychiatric disorder was indicated by records of a hospitalization or cause of death with a diagnosis related to psychiatric illness and/or self-inflicted injuries. The ICD-8 (1973–86), ICD-9 (1987–96) and ICD-10 (1997–2008) classifications were used for categorization of hospital discharges. These variables were created for birth parents as well as for caring parents.

Descriptive characteristics of the study population are shown in Table 1. Foster children and national adoptees were on average slightly older than the other study groups. More foster parents lived in rural areas compared to parents from the other study groups. They also tended to have lower SES. Rates of substance abuse and psychiatric disorders among caring parents for adoptees and foster children were similar to parents of majority population peers. Indications of substance abuse and psychiatric disorders were very common among birth parents of foster children, with 55% of fathers having an indication of alcohol abuse, and 56% of mothers an indication of psychiatric ill health, For adoptees, these rates among birth parents were considerably higher than for peers not in care, but lower than for the foster care group. Indications of substance abuse for both birth parents were noted in 1% of the general population, 9% among the adoptees, and for 37% of the foster children (Table 1). Almost every second child in the national cohort (45%; not shown in tables) whose birth parents both had indications of substance abuse grew up as adoptees or in long term foster care. In the total population, alcohol related criminality was the most common outcome (2.4%; see Table 2), and alcohol related hospital treatment the least common (1.1%). Birth as well as caring parents' alcohol and drug abuse or psychiatric illness was associated with higher incidence of all outcomes, increasing the rates up to five times. All outcomes were as expected more frequent in men than in women (e.g., 1.5% vs. 0.9% for drug related hospital admissions and to 4.2% vs. 0.5% for alcohol related criminality; Table 2). In Table 3, outcome rates by study group and gender are displayed. More than one in four (26.1%) of the former foster boys had at least one indication of substance abuse by 2008, more than a twofold rate compared to adopted boys, and almost fourfold compared to general population peers. Such relative figures for former foster girls tended to

2.4. Socio-demographic confounders A recent longitudinal national cohort study of 1.4 million Swedish born found links between parental SES and the risk of substance abuse in offspring, after controlling for parental morbidity (Gauffin et al., 2013), Therefore socio-demographic confounder variables describing the substitute home were created with data from the censuses 1985 and 1990, and from the Register of the Total Population (held by Statistics


1957

Table 1 Distribution (percent) of socioeconomic indicators of the caring parents, and of parental indicators, after study group.

Sex Year of birth

Residency

Single parent SEI

Caring mothers

Caring fathers

Birth mothers

Birth fathers

Substance abuse in both birth parents

Male Female 1973–1975 1976–1978 1979–1981 1982–1985 Metropolitan area Urban area Rural district Yes Unclassified Manual labor Skilled labor White collar 1 White collar 2 White collar 3 Farmer, self employed Alcohol abuse Drug abuse Psychiatric illness Alcohol abuse Drug abuse Psychiatric illness Alcohol abuse Drug abuse Psychiatric illness Alcohol abuse Drug abuse Psychiatric illness Alcohol abuse Drug abuse Any substance abuse

National adoptees

Foster children

Siblings to NA

Siblings to FC

General population

N = 1012 %

N = 2408 %

N = 348 %

N = 846 %

N = 952,935 %

53.7 46.3 37.1 25.0 19.1 18.9 26.7 53.7 19.5 8.3 6.8 11.9 9.6 14.0 29.8 26.3 1.6 3.2 1.3 6.6 5.7 0.7 4.0 19.1 9.9 29.3 24.6 8.1 13.6 6.9 3.0 8.9

51.3 48.7 40.4 30.6 19.4 9.5 20.3 52.0 27.7 7.3 10.7 22.8 17.9 12.6 22.4 12.1 1.5 2.6 0.8 6.6 6.8 0.5 4.9 43.8 27.8 56.0 55.4 24.7 32.5 29.2 14.7 36.7

52.3 47.7 23.9 24.7 28.7 22.7 28.2 49.9 21.9 3.2 5.7 12.6 13.5 10.9 27.3 27.9 2.0 1.4 0.6 8.6 6.6 0.6 4.6 1.4 0.6 8.9 7.5 0.6 4.6 0.0 0.0 0.0

49.9 50.1 37.4 22.8 18.3 21.5 22.2 47.4 30.3 5.4 4.8 20.8 20.9 15.1 21.5 14.8 2.0 2.4 0.7 4.8 8.0 0.2 5.6 2.4 .7 4.8 10.8 1.5 6.6 0.7 0.1 0.8

51.9 48.1 25.3 22.4 22.3 30.0 27.7 49.8 22.6 10.9 6.0 16.4 16.4 15.7 24.9 19.1 1.4 2.9 0.9 6.2 7.3 0.9 4.0 2.8 1.0 6.6 11.3 2.0 6.2 0.9 0.2 1.1

NA = national adoptees, FC = foster children.

be even higher on all outcomes, even though prevalence figures were considerably lower.

3.1. Cox regression modeling In the Cox regression analysis for alcohol related outcomes presented in Table 4, former foster children had the highest risks for hospital treatment (HR 6.0) and criminality (HR 3.7) compared to general population peers, in age and sex adjusted models. Adoptees had HRs of 2.5 (hospital treatment) and 1.8 (criminality). Adjusting the model for characteristics of the caring family (Models II and III) had no or marginal effects on the HRs for the foster children and the adoptees. Adjusting for birth parents' morbidity in Model IV decreased HRs for adoptees and former foster children to HRs of 1.6–1.7 (hospital treatment) and 1.4–1.3 (criminality), and produced similar HR estimates for both groups. For illicit drug use, presented in Table 5, Cox regression patterns were basically the same with age/sex adjusted HRs of 6.7 and 3.0 for hospital admissions for former foster children and adoptees, respectively and 5.2 and 1.8 for drug related criminality (Model I), decreasing to HRs of 1.8–1.6 (hospitalization) and 1.2–1.4 (criminality) in the fully adjusted model IV. The HRs of the sibling study groups were similar to the general population, with the exception of the foster parents' biological children that had a higher HR (1.5) for alcohol related criminality in the fully adjusted model (Model IV, Table 4). When analyzing boys and girls separately (results not shown in tables), girls in foster care tended to have higher HRs for all outcomes than foster care boys. This was most pronounced for drug related criminality where boys in foster care had a HR of 4.7 (4.0–5.5) and girls had a HR of 7.5 (5.8–9.7) in an age and sex adjusted model (difference

p b 0.005 in a gender interaction analysis). Adopted girls and boys, however, had similar HRs. One could argue that the substitute care should also be measured as a factor that may reduce serious consequences of alcohol/drug use. Thus it would be interesting to examine possible effects on substance abuse related deaths, and not just look at hospital treatment. Figures for such deaths in our dataset were crudely congruent with data on substance abused related criminality and hospital care, but cases were too few for any reasonably well-founded interpretation (not shown in tables, available on request).

4. Discussion In this register-based national cohort study of former children in substitute care, followed to young adulthood (ages 27–35) with data on caring as well as birth parents, former foster children were found to have four to sevenfold increased risks for alcohol and illicit drug misuse/abuse, compared with the general population. Adoptees' risks were lower but also clearly elevated. Elevated risks were strongly associated with birth parents' substance abuse and psychiatric morbidity, while the characteristics of the substitute home seemed to have only a marginal (statistical) influence. Our results point to the importance of risk factors preceding entries to substitute care, some most likely genetically related. Epidemiological evidence for a heritability of alcohol and drug abuse comes from twin and adoption studies (e.g., Goodwin et al., 1973, 1974; Kendler, Heath, Neale, Kessler, & Eaves, 1992, 2000, 1998, 2012; Kendler, Karkowski, Corey, Prescott, & Neale, 1999, Kendler, Karkowski, Neale, & Prescott, 2000, Kendler, Karkowski, Prescott, Neale, & Pedersen, 1998, Kendler et al., 2000, 2012). In a study of adopted away sons of alcoholics in

1958


Table 2 Frequency of outcome by socio-demographic and parental indicators (total study population). N

Sex Year of birth

Residency

Single parent household (caring mother) Socio economic index (caring mother)

Caring mothers

Caring fathers

Birth mothers

Birth fathers

Study groups

Male Female 1973–1975 1976–1978 1979–1981 1982–1985 Metropolitan area Urban area Rural district Yes Unclassified Manual labor Skilled labor White collar 1 White collar 2 White collar 3 Farmer, self employed Alcohol abuse Drug abuse Psychiatric illness Alcohol abuse Drug abuse Psychiatric illness Alcohol abuse Drug abuse Psychiatric illness Alcohol abuse Drug abuse Psychiatric illness National adoptees Foster children Siblings to NA Siblings to FC General population peers

497,343 460,206 242,517 214,991 213,753 286,288 263,623 474,955 215,564 104,415 57,994 156,900 157,465 150,407 238,214 183,117 13,452 27,401 8605 59,026 69,648 8708 37,881 28,040 10,267 64,976 109,068 19,420 59,909 1012 2408 348 846 952,935

Denmark, Goodwin and associates found a fourfold increased rate of alcoholism compared to sons of non-alcoholics (Goodwin et al., 1973). Our findings are to a certain extent contradictory to results from Bohman and Sigvardsson's rigorous longitudinal studies of 600 Stockholm infants initially put up for adoption 1956–57 (e.g., Bohman, 1971, 1995; Bohman & Sigvardsson, 1980a, 1982, 1990). They reported that birth parental background factors did not explain the differences between adopted and fostered boys for register records of crime and substance abuse at age 23 (Bohman & Sigvardsson, 1980a,b). However, these analyses were reported only briefly in text, and not in detail. The foster children in our study are a strongly selected group with a high proportion of birth parental substance abuse in the background. More than one third (37%) had indications of substance abuse for both birth parents, among adoptees it was only one in twelve (8%). Possibly, the influence of substitute care as such has been similar for both groups.

Alcohol related

Drug related

Hospital admission in %

Criminality in %


Criminality in %

1.5 0.8 1.1 1.1 1.2 1.2 1.3 1.0 1.1 2.2 1.9 1.7 1.2 1.0 0.9 0.7 0.5 3.7 4.1 2.6 2.3 3.1 2.0 4.0 4.5 2.8 2.9 4.2 2.8 2.8 6.4 0.9 0.9 1.1

4.2 0.5 2.7 2.5 2.3 2.1 2.5 2.3 2.5 4.2 4.1 3.6 3.0 2.4 1.7 1.3 1.5 6.6 7.6 4.2 4.9 6.3 3.5 6.9 8.0 4.5 5.6 7.7 4.4 4.5 8.7 0.9 3.5 2.4

1.5 0.9 1.0 1.2 1.4 1.4 1.6 1.2 0.9 2.9 2.4 1.8 1.4 1.1 0.9 0.7 0.4 4.3 7.0 3.1 2.6 4.9 2.2 4.7 7.4 3.3 3.4 7.0 3.1 3.5 7.3 0.6 0.8 1.2

3.2 0.8 1.4 1.9 2.4 2.4 2.6 1.9 1.6 4.8 3.9 3.1 2.4 2.0 1.5 1.2 0.5 6.6 10.8 4.3 4.3 8.5 3.3 6.9 11.2 4.6 5.5 11.2 4.5 3.5 9.1 0.6 1.9 2.0

The results from the regression models suggest that observed differences in risks for substance abuse after age 15 may be largely attributed to heritable and early childhood related risk factors, and not the form of substitute care per se. Several studies indicate that adoption is a superior form of substitute care when it comes to cognitive development, and other closely related outcomes. In an analysis of 17 studies with more than 2000 adoptees and controls, Christoffersen (2012) found that adoptees scored better on IQ and school performance than their non-adopted siblings, or children who grew up in foster care (see also Christoffersen et al., 2007). Vinnerljung and Hjern (2011) used Swedish register data to compare school grades at age 16, cognitive ability at conscription (age 18, boys only), educational attainment at age 26, and self-support at age 25 for 900 adoptees and 3100 young adults that grew up in foster care (more than 12 years in care before age 18), and 900,000 majority population peers. The foster children fell clearly short of the adoptees on all

Table 3 Outcomes — frequencies in study groups in percent, by gender. N

Boys

Girls

National adoptees Foster children Siblings to NA Siblings to FC General population comparison National adoptees Foster children Siblings to NA Siblings to FC General population comparison

543 1236 182 422 494,960 469 1172 166 424 457,975

Alcohol related

Drug related


Criminality in %


Criminality in %

3.7 8.1 0.0 1.7 1.4 1.7 4.6 1.8 0.2 0.7

7.6 14.7 1.6 6.9 4.2 1.1 2.4 0.0 0.2 0.5

3.7 8.6 1.1 0.9 1.5 3.2 6.0 0.0 0.7 0.9

5.2 12.9 1.1 3.3 3.1 1.5 5.1 0.0 0.5 0.8


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Table 4 Summaries of Cox regression models for alcohol related outcomes. HR in Bold are statistically significant (p b 0.05). Model Ia

Hospital treatment (alcohol associated)

Criminality (alcohol related)

National adoptees Foster children Siblings to NA Siblings to FC General population National adoptees Foster children Siblings to NA Siblings to FC General population

Model IIb

Model IIIc

Model IVd

HR

(95% CI)

HR

(95% CI)

HR

(95% CI)

HR

(95% CI)

2.48 5.99 0.76 0.86 1 1.82 3.68 0.35 1.50 1

(1.71–3.59) (5.11–7.03) (0.25–2.36) (0.43–1.71)

2.74 5.75 0.87 0.87 1 2.06 3.38 0.40 1.48 1

(1.89–3.97) (4.90–6.74) (0.28–2.70) (0.44–1.74)

2.73 5.83 0.88 0.88 1 2.08 3.41 0.41 1.49 1

(1.88–3.95) (4.97–6.84) (0.28–2.73) (0.44–1.76)

1.60 1.71 0.92 0.87 1 1.38 1.29 0.42 1.47 1

(1.10–2.32) (1.45–2.03) (0.30–2.85) (0.43–1.73)

(1.36–2.43) (3.21–4.21) (0.11–1.09) (1.05–2.15)

(1.54–2.75) (2.94–3.87) (0.13–1.24) (1.03–2.11)

(1.56–2.78) (2.98–3.91) (0.13–1.26) (1.04–2.13)

(1.03–1.84) (1.12–1.49) (0.14–1.30) (1.03–2.10)

a

Model I — adjusted for age and sex. Model II — adjusted for age, sex and socio-demographic determinants of the caring mother (residency, single parent household, SES). c Model III — adjusted for age, sex, socio-demographic determinants of the caring mother (residency, single parent household, SES) and caring mothers' + caring fathers' alcohol abuse, drug abuse and psychiatric illness. d Model IV — adjusted for age, sex, socio-demographic determinants of the caring mother (residency, single parent household, SES) and birth mothers' + birth fathers' alcohol abuse, drug abuse and psychiatric illness. b

outcomes, also after adjustments for birth maternal education, parental psychiatric illness and addiction problems, and age at entering the child welfare system. Other Swedish national cohort studies have found highly elevated risks for serious psychiatric morbidity among young adults raised in foster care, even after adjustments for parental psychiatric morbidity (Hjern, Vinnerljung, & Lindblad, 2004; Vinnerljung, Hjern, & Lindblad, 2006). But in a recent study, Vinnerljung and Hjern (submitted for publication) used register data for 765,000 Swedish adults to examine use of prescribed psycho-tropics at ages 28–36, well into mature adult age, among out-of-home care alumni and national adoptees. High consumption of psychotropic drugs was strongly associated with psychiatric morbidity in birth parents. In a comparison of the adoptees and a subsample of former foster children who had been in care for more than 10 years before age 18, risk rates were mostly similar for the two groups after adjustments in Cox regression models for birth maternal socioeconomic background, and for indications of parental psychiatric morbidity and substance abuse. Taken together, these studies suggest that long term outcomes of different forms of substitute care may not be uniform, but may vary between different life areas, with less positive outcomes in areas where heritable and early childhood factors are particularly important. It is noteworthy that foster care seemed to have a slightly stronger influence on girls' future risks for future substance abuse, compared to male foster care peers. Some previous studies — but not all (e.g., Langbehn, Cadoret, Caspers, Troughton, & Yucuis, 2003) — have indicated that family

environment may have a greater influence on girls than on boys regarding risks for drug use (Block et al., 1988). This could mean that girls may be more susceptible to the process of coming into and growing up in foster care, where placement disruptions are common and affect developmental pathways (e.g., Newton, Litrownik, & Landsverk, 2000). Children with substance abusing birth parents are more likely to experience placement instability than other fostered children (Barth et al., 2006; Connell et al., 2007; Vanderploeg et al., 2007). Girls may possibly be more affected by the instability of long term foster care than boys, but this is a speculation that warrants a study of its own. Another interesting finding is that the sibling groups differed only marginally from majority population peers. We are not aware of any previous comparative study of adoption and foster care that has included environmental siblings. Siblings to adoptees tended to be slightly better off than siblings of foster children, but overall results suggest that both adoptive and foster families in Sweden constitute “normal” and average families. 4.1. Methodological issues The use of register data in a national cohort has some major advantages in relation to previous studies dealing with similar research questions. It has minimized attrition in the follow-up, which has been a major problem in most studies of substance abuse and former children from substitute care. It enabled us to create sizable study groups of children from two forms of substitute care, and to follow them from

Table 5 Summaries of Cox regression models for illicit drug related outcomes. HR in Bold are statistically significant (p b 0.05). Model Ia

Hospital treatment (drug associated)

Criminality (drug related)

a

National adoptees Foster children Siblings to NA Siblings to FC General population National adoptees Foster children Siblings to NA Siblings to FC General population

Model IIb

Model IIIc

Model IVd

HR

(95% CI)

HR

(95% CI)

HR

(95% CI)

HR

(95% CI)

3.00 6.69 0.47 0.71 1 1.82 5.25 0.28 1.02 1

(2.15–4.18) (5.76–7.76) (0.12–1.88) (0.34–1.50)

3.38 6.56 0.57 0.75 1 2.06 5.15 0.34 1.06 1

(2.43–4.71) (5.65–7.62) (0.14–2.27) (0.36–1.58)

3.31 6.68 0.58 0.77 1 2.05 5.24 0.36 1.08 1

(2.38–4.62) (5.75–7.75) (0.15–2.32) (0.37–1.62)

1.81 1.60 0.61 0.74 1 1.20 1.42 0.37 1.04 1

(1.30–2.53) (1.37–1.88) (0.15–2.45) (0.35–1.56)

(1.31–2.54) (4.59–6.00) (0.07–1.12) (0.62–1.66)

(1.48–2.88) (4.50–5.89) (0.09–1.37) (0.65–1.73)

(1.47–2.86) (4.58–5.99) (0.09–1.43) (0.66–1.77)

(0.86–1.67) (1.23–1.63) (0.09–1.50) (0.63–1.69)

Model I — adjusted for age and sex. Model II — adjusted for age, sex and socio-demographic determinants of the caring mother (residency, single parent household, SES). Model III — adjusted for age, sex, socio-demographic determinants of the caring mother (residency, single parent household, SES) and caring mothers' + caring fathers' alcohol abuse, drug abuse, and psychiatric illness. d Model IV — adjusted for age, sex, socio-demographic determinants of the caring mother (residency, single parent household, SES) and birth mothers' + birth fathers' alcohol abuse, drug abuse, and psychiatric illness. b c

1960


childhood into young adulthood. But all register studies have their inherent shortcomings, and ours is not an exception. Firstly, national register data do not contain information about the cause for placement in out-of-home care or adoption. For the children whose birth parents had register indications of substance abuse, we do not know if entries into substitute care were triggered by parental substance abuse only, by parental substance abuse in combination with other factors (e.g., child neglect), or by other temporal factors (e.g., single mother with severe psychiatric ill-health). This subgroup of children in substitute care constitutes a small, selected group of all children in the national population with substance abusing parents. It is probable that adjustments for various confounders (e.g., parental co-morbidity) in the analyses do not fully balance this selection. Secondly, the validity of the indications of alcohol and/or illicit drug abuse in register data is far from perfect. The proportion of hidden alcohol and illicit drug abuse is likely to be high, potentially even more so in specific population groups. For example, those from higher socioeconomic backgrounds may have better resources to cope with substance abuse problems without assistance from hospital-based care. This could potentially have created an overestimation in our data of these outcomes in the more socially vulnerable populations, to which many of the former child welfare clients belong in young adulthood (e.g., Berlin et al., 2011). Thirdly, another limitation concerns the indicators of parental psychopathology and substance abuse. These were constructed from observations during and after the cohort members' childhood years. This approach has been frequently used in Scandinavian register studies (e.g., Christoffersen & Soothill, 2003; Franzén et al., 2008; Kendler et al., 2012; Vinnerljung & Hjern, 2011). The vast majority of medical interventions for psychiatric disorders and addiction is delivered in outpatient care, especially before mature adult age, and not noted in the Hospital Discharge Register. Death and hospitalizations due to addiction related causes most often represent cases of long term substance abuse (Christoffersen & Soothill, 2003). We are aware that this is casting the net wide, and the results are short on precision. Again, it is difficult to estimate the consequences of these imperfections. It is also probable that the results are affected by contextual factors. They may not be generalizable to countries outside Scandinavia (cp. Braciszewski & Stout, 2012). Finally, even though we have controlled for several important confounders, register data does not enable us to chart developmental processes where genetically related vulnerability and exposure to a host of environmental risk mechanism interface. 4.2. Conclusions and implications Children in substitute care are at a high risk for alcohol and drug abuse if substance abuse is present in their birth parents' history, especially if this is the case for both parents. Substitute care in itself does not seem sufficient to break a probability-based intergenerational “cycle” of substance abuse. Our results may also serve as a caution against firm conclusions from comparisons of long term outcomes between adoption and long-term foster care, if important parental related selection factors have not been taken into account. If we turn our eyes towards possible implications of our findings for policy and practice it is of imperative importance to return to the crude rates displayed in Table 2. In spite of high hazard ratios in regression models, it was a clear minority of all children with a birth family history of substance abuse — including adoptees and foster children — that had indications of substance abuse in young adulthood. As Rutter (1998) has emphasized many times in his work on children from adverse family backgrounds: Whenever we see inter-generational continuity, we see far more of discontinuity. Both adoption and foster care history is saturated with genetic determinism, in Sweden and other countries (e.g., Bohman, 1995, 1997; Farrell Smith, 2002). This created a corps of “un-adoptable children” who was filtered out of the adoption system. Children with e.g., substance abusing parents were considered genetically

tainted, and perceived by social workers as being unable to meet expectations from often well-educated adoptive parents. In Sweden, they were placed in long term foster care, usually in the rural parts of the country, and in families with low education (Bohman, 1995, 1997). Subsequently, preventive interventions as “genetic counseling” (e.g., Austin & Honer, 2004) may very well cause harm by contributing to a return of genetic determinism in adoption and foster care, and may also cause interfamily stigmatization (e.g., Austin & Honer, 2004; Farrell Smith, 2002), besides having very limited clinical validity (Kendler, 2013; Yan et al., 2013). Since results from population studies cannot be used for individual prediction, our study does not provide arguments for returning to the old common practice of excluding children with substance abusing parents from adoption. But there is one salient lesson from several landmark cross-adoption studies (e.g. Cloninger et al., 1981; Sigvardsson et al., 1996), that should influence practice for adoption and foster care agencies. When placing children with a family history of substance abuse in substitute long-term care, it seems reasonable to expect lower risks of intergenerational continuity of addiction if these children grow up in the care of adoptive/foster parents without similar problems (Cloninger et al., 1981; Sigvardsson et al., 1996). Therefore, it makes sense to do a reinforced screening (for example with standardized instruments) for alcohol/drug consumption and attitudes in the substitute family. Acknowledgments This research was supported by Riksbankens Jubileumsfond (RJ) and the Swedish Research Council for Health, Working Life and Welfare (FORTE). References Aarons, G. A., Monn, A.R., Hazen, A. L., Connelly, C. D., Leslie, L. K., Landsverk, J. A., et al. (2008). Substance involvement among youths in child welfare: The role of common and unique risk factors. American Journal of Orthopsychiatry, 78, 340–349. Andersson, G. (1991). Socialt arbete med små barn [Social work with young children]. Lund: Studentlitteratur. Arteaga, I., Chen, C. -C., & Reynolds, A. J. (2010). Childhood predictors of adult substance abuse. Children and Youth Services Review, 32, 1108–1120. Austin, J. C., & Honer, W. G. (2004). The potential impact of genetic counseling. Clinical Genetics, 67, 134–142. Barth, R. P., Gibbons, C., & Guo, S. (2006). Substance abuse treatment and the recurrence of maltreatment among caregivers with children living at home: A propensity score analysis. Journal of Substance Abuse Treatment, 30, 93–104. Bennett, E. M., & Kemper, K. J. (1994). Is abuse during childhood a risk factor for developing substance abuse problems as an adult? Journal of Developmental and Behavioral Pediatrics, 15, 426–429. Berlin, M., Vinnerljung, B., & Hjern, A. (2011). School performance in primary school and psychosocial problems in young adulthood among care leavers from long term foster care. Children and Youth Services Review, 33, 2489–2497. Block, J., Block, J. H., & Keyes, S. (1988). Longitudinally foretelling drug usage in adolescence: Early childhood personality and environmental precursors. Child Development, 59, 336–355. Bohman, M. (1971). Är det sociala arvet ärftligt? [Is the social heritage hereditary?] Läkartidningen, 68, 4616–4624. Bohman, M. (1978). Some genetic aspects of alcoholism and criminality. Archives of General Psychiatry, 35, 269–276. Bohman, M. (1995). De svenska adoptivbarnen: Det sociala arvet i ett historiskt perspektiv [Swedish adopted children: “Social heredity” in a historical perspective]. Socialmedicinsk Tidskrift, 8, 308–319. Bohman, M. (1997). Nature and nurture. Lessons from Swedish adoption surveys. Adoption and Fostering, 21, 19–27. Bohman, M., & Sigvardsson, S. (1980a). Negative social heritage. Adoption and Fostering, 101, 25–31. Bohman, M., & Sigvardsson, S. (1980b). Barn i fosterhem klarade sig sämst [Children in foster care fared worst]. Socionomen, #19. (pp. 8–9), 8–9. Bohman, M., & Sigvardsson, S. (1982). Adoption and fostering as preventive measures. In J. Anthony, & C. Chiland (Eds.), The child in his family, children in turmoil: Tomorrow's parent (pp. 171–180). New York: John Wiley & Sons. Bohman, M., & Sigvardsson, S. (1990). Outcome in adoption: Lessons from longitudinal studies. In I. D. Brodzinsky, & M. Schechter (Eds.), The psychology of adoption (pp. 93–107). New York/Oxford: Oxford University Press. Braciszewski, J., & Stout, R. (2012). Substance use among current and former foster youth: A systematic review. Children and Youth Services Review, 34, 2337–2344. Brady, K. T., & Randall, C. L. (1999). Gender differences in substance use disorders. Psychiatric Clinics of North America, 22, 241–252. Cadoret, R. J., Cain, C. A., & Grove, W. M. (1980). Development of alcoholism in adoptees raised apart from alcoholic biologic relatives. Archives of General Psychiatry, 78, 561–563.

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