The relationship between cognitive functions, somatization and ...

The relationship between cognitive functions, somatization and behavioural coping in patients with multiple functional somatic symptoms Nord J Psychiatry Downloaded from informahealthcare.com by Statsbiblioteket Tidsskriftafdeling on 03/22/11 For personal use only.

NICOLINE M. HALL, RUTA KUZMINSKYTE, ANDERS D. PEDERSEN, EVA ØRNBØL, PER FINK

Hall NM, Kuzminskyte R, Pedersen AD, Ørnbøl E, Fink P. The relationship between cognitive functions, somatization and behavioural coping in patients with multiple functional somatic symptoms. Nord J Psychiatry 2010;Early Online,1–9. Background and aims: Patients with multiple functional somatic symptoms (MFS) often express cognitive complaints. The aim of this descriptive study was to investigate whether these patients have cognitive deficits and whether the patients’ cognitive functioning relates to their experience of physical and psychological distress and to their use of pain-related coping strategies. Methods: Neuropsychological assessment of verbal ability, psychomotor speed, attention, working memory, perceptual organization and memory, was conducted on 22 MFS patients and 27 healthy age- and gender-matched controls. Psychological distress, health anxiety, health status and pain coping were measured with questionnaires [Symptom Checklist 90-Revised (SCLsomatization, SCL-depression, SCL-anxiety), the Whiteley-7 scale, the Short Form (SF-36) and the Coping Strategies Questionnaire (CSQ)]. Results: For patients, a high score on the SCLsomatization subscale was associated with poor performance on tests of attention and psychomotor speed, and with a high score on the coping scale Increasing behavioural activities. A high score on this coping scale was associated with poor performance on tests of verbal ability and executive functioning. After controlling for years of education, controls performed significantly better than patients on verbal as well as performance IQ scales but not on tests of memory. Conclusion: In the present study, we found that physical complaints are related to deficits in attention and psychomotor speed. Moreover, our results suggest that poor verbal skills may play a role in the development of MFS because of an increased tendency to apply behavioural/avoidant coping strategies. We suggest that treatment of MFS should involve training of attention as well as practicing the use of cognitive coping strategies. • Cognitive functions, Coping, Functional somatic symptoms, Pain, Somatization. Nicoline Marie Hall, Forskningsklinikken for Funktionelle Lidelser, Aarhus Sygehus, Noerrebrogade 44, 8000 Aarhus C, Denmark, E-mail: [email protected]; Accepted 27 September 2010.

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unctional, or medically unexplained, symptoms are physical symptoms that are not attributable to any known conventionally defined disease and are unsupported by clinical or para-clinical findings. These symptoms are prevalent in the general population and in all medical settings (1, 2), and can be persistent, disabling and costly for society (3–6). In addition to complaints from various organ systems, patients presenting with functional somatic symptoms frequently report non-specific symptoms such as pain, headache, fatigue and dizziness, as well as problems with memory, attention and concentration (1, 7). However, it is not known how these patients’

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neuropsychological test performance relates to their physical and psychological well-being. Knowledge about potential cognitive deficits and their role in the development and maintenance of functional somatic symptoms are important for the development of treatment strategies for this patient group. Patients diagnosed with various functional somatic syndromes (e.g. fibromyalgia syndrome, irritable bowel syndrome, chronic fatigue syndrome, chronic benign pain syndrome and chronic whiplash-associated disorders) share the same symptoms (8) and it has been suggested that a single disorder might underlie the various syndromes DOI: 10.3109/08039488.2010.528024

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N. M. HALL ET AL

(1, 9–11). In psychiatry, the diagnosis of somatoform disorder is often used. Because the diagnostic criteria in DSM-IV and ICD-10 are thought be overlapping and imprecise (12), a simple count of functional somatic symptoms has often been used in research (13–15). In the present study, we consider functional somatic symptoms part of a single phenomenon ranging from a few to multiple medically unexplained symptoms originating from different organ systems. The present investigation focuses on the most severe end of the scale, i.e. patients with multiple functional somatic symptoms (MFS). A number of studies have used neuropsychological tests to investigate the cognitive functioning of patients with various functional syndrome diagnoses, particularly chronic fatigue syndrome (e.g. 16–21), fibromyalgia syndrome (22–26) and whiplash-associated disorders (27– 31). In a pilot study, Niemi et al. (32) found that somatizing patients without other Axis 1 psychiatric illnesses on average performed at a lower level than healthy controls on tests of verbal ability and verbal episodic memory and were slower on attentional tasks. Although findings vary considerably between studies, and within studies of specific functional syndromes, there seems to be a general agreement that some domains of cognitive functioning are impaired in patients with functional somatic symptoms and disorders. Various explanations for such deficits have been proposed. Cognitive deficits in MFS patients could be related to the notion of cognitive load (33) or acute or chronic stress reactions (34, 35). Based on these explanatory models, we would expect high ratings of physical and psychological distress to be related to poor performance on neuropsychological tests requiring a high degree of effortful processing. On the other hand, specific patterns of cognitive functioning may also be a risk factor for the development of functional somatic symptoms by affecting the ability of the individual to interpret bodily symptoms correctly and apply appropriate coping strategies in response to bodily signals. It has been shown that patients’ use of coping strategies in response to symptoms affects the severity of symptoms in chronic pain (36, 37) and after whiplash injury (38). An association has been found between choice of coping strategies and educational level (39) and it may be hypothesized that poor neuropsychological test performance is associated with specific maladaptive coping behaviours.

Aims The present explorative study was designed to: 1) determine whether patients with MFS have neuropsychological deficits, and, if they do, whether a particular pattern of deficits exists; 2) determine whether neuropsychological test performance is related to physical and psychological distress in the patients; and 3) investigate the

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relationship between somatic symptoms and patients’ use of pain-related coping strategies, and between use of coping strategies and neuropsychological functioning.

Material and methods Participants Patients were recruited from a previous investigation at the Aarhus University Hospital (6), which examined 1785 consecutive patients consulting their general practitioners for a new health problem. A stratified sample of 701 patients was interviewed by trained physicians using a standardized psychiatric interview (Schedules for Clinical Assessment in Neuropsychiatry; SCAN; 40) approximately 3 years before the onset of the current study. SCAN covers all types of psychiatric disorders and includes an extensive section on physical health. This section explores 86 physical symptoms distributed across seven symptom groups. Symptoms that, after a thorough investigation (including reviewing the medical records), could not be medically explained, had been present for the past 2 years and had caused significant impairment, were considered functional somatic symptoms. Eighty patients, who had six or more functional somatic symptoms according to the SCAN interview and no other psychiatric or non-psychiatric diagnoses at the time of the previous investigation, were invited to participate in the current study. Twenty-six patients responded to the invitation and were interviewed with SCAN for the second time. Two of the patients were excluded because of a concurrent physical disease, and one was excluded because of a concealed history of alcohol abuse. One moved abroad during the present investigation. The remaining 22 patients presented six or more functional somatic symptoms of at least 2 years’ duration, had no physical or mental disorders, and no substance abuse. At the onset of the current study, the 22 included patients had an average of 26.5 functional somatic symptoms, ranging from 10 to 52 symptoms, distributed across all organ systems. Mean age at onset of functional somatic symptoms was 22 years (range 7–38) and mean duration 10.5 years (range 5–30). Eight were on medication; none was medicated on the day of the neuropsychological examination. Twenty-seven healthy, medication-free volunteers, having no current physical or psychiatric symptoms and no history of physical or psychiatric disorder or abuse, were recruited through an advertisement in a local paper and assessed following the same procedure as the one used for the patients. Patients and controls were matched on age (mean 36.6 (25–47) and 35.6 (24–45), respectively; Mann–Whitney Z 0.584, P 0.559) and gender (72 and 70% females, respectively; χ2 0.033, df 1, P 0.856), but not for years of education [mean 12 (10–22) and 16 (11–21) years, respectively; Mann–Whitney Z 3.07, NORD J PSYCHIATRY·EARLY ONLINE·2010

SOMATIZATION,

P0.0021]. All participants could speak and write Danish and received written and oral information about the project. A written informed consent was acquired from all participants and the study was approved by the regional scientific ethics committee.

Measures


Questionnaires Health status was assessed using the SF-36, a validated self-report questionnaire with scaled scores giving levels of current functioning that vary from 0 to 100% of normal. Physical and psychological symptoms were assessed using subscales from the Symptom Checklist 90-Revised (SCL90-R, 41). Somatization was measured with a 12-item symptom checklist, anxiety with four items and depression with six items (42–46), and health anxiety/somatization with seven items (Whiteley-7, 47). Responses to the SCL subscales and Whiteley-7 were given on a 5-point scale. The response on each item was dichotomized with responses 1 and 2 (“not at all” or “a little”) giving a score of 0 and responses 3–5 (“somewhat”, “quite a lot” or “very much”) giving a score of 1. Pain coping was assessed with the Coping Strategies Questionnaire (CSQ; 48). Patients were asked to indicate the extent to which they use certain coping strategies on a 7-point Likert scale (0, never; 6, always). Forty-eight items are summarized into subscales measuring how often patients report using six different cognitive pain coping strategies: Diverting attention, Coping self-statements, Praying or hoping, Reinterpreting pain sensations, Catatrophizing and Ignoring pain; and one behavioural strategy: Increasing behavioural activities. The CSQ includes two additional items targeting control over and ability to decrease pain. Here, the average score on these two items is used to express the experience of control over pain.

Current physical and psychological distress Patients rated their present levels of physical discomfort, pain, sadness/depression, anxiety, headache, fatigue, stress and negative cognitions about the impact of their condition on their present as well as their future situation. Each of the nine variables was rated on a visual analogue scale (VAS; range 0–10).

Neuropsychological tests Participants completed a comprehensive neuropsychological evaluation. Verbal ability was measured with Information, Vocabulary, Comprehension and Similarities age-corrected scaled scores from the Wechsler Adult Intelligence Scale— Revised (WAIS-R; 49). Psychomotor speed was assessed using the Digit Symbol age-corrected scaled score from the WAIS-R, Trail making test A time to completion (TMT A; 50), and number of correct items from the d2-Test (51). Attention/Working memory was measured using Digit Span and Arithmetic age-corrected scaled scores and the Digit NORD J PSYCHIATRY·EARLY ONLINE·2010

COGNITIVE FUNCTIONS AND COPING

span forward and Digit span backward raw scores (WAISR). Executive function was measured with the Trail making test B time to completion (TMT B; 50), Short category test raw error score (SCT; 52) and Controlled Oral Word Association number of words (COWA; 53), and Perceptual organization was assessed using WAIS-R Block Design, Picture Arrangement, Picture Completion and Object Assembly age-corrected scaled scores. Verbal and visual Memory was measured with the Auditory Verbal Learning Test (AVLT; 54) total score list A (sum of score on five learning trials), immediate recall of interference list B, retention of list A after interference, delayed recall of list A and delayed recognition of list A and B; and the Logical memory immediate, Logical memory delayed, Visual reproduction immediate and Visual reproduction delayed from the Wechsler Memory Scale—Revised (WMS-R; 55).

Statistical analysis The scores on questionnaire scales and neuropsychological tests are not normally distributed. Therefore, the neuropsychological test scores of patients and controls are compared using the non-parametric Mann–Whitney test. Linear regression analysis is applied to control for differences in education. The relationship between patients’ neuropsychological test scores, and questionnaire and VAS scores is quantified with correlation coefficients derived from Spearman’s correlation analyses. In the correlation analyses, we do not control for level of education.

Results Questionnaires As shown in Table 1, patients reported more symptoms than healthy controls on all subscales of the SCL and SF-36, on the Whiteley scale, and on all VAS scales except anxiety. On the CSQ, patients reported using Increasing behavioural activities, Catastrophizing and Praying or hoping as means of coping with pain more often, and reported significantly less control over their pain, than healthy controls.

Neuropsychological tests The average scores, standard deviations and range of scores of patients and controls on the neuropsychological tests are given in Table 2. As indicated in the second column, healthy controls scored significantly higher than patients on most tests. All effect sizes for significant differences are large or medium. After control for education, patients and healthy controls differed on Verbal IQ, Performance IQ and Full IQ. On individual tests, group differences were found on all subtests of verbal ability, and on Block design and AVLT immediate recall of list B. If group differences are controlled for verbal ability (a composite of Information, Vocabulary, Comprehension and Similarities), the only significant difference between the two groups is on Block Design.

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N. M. HALL ET AL

Table 1. Average scores for patients and healthy controls on Symptom Checklist 90-Revised (SCL) subscales, the Whiteley-7 scale, Short Form (SF-36) subscales (% of normal), Coping Strategies Questionnaire (CSQ) subscales (scale 0–6) and visual analogue scale (VAS) ratings (scale 1–10).


Measure SCL-somatization SCL-4 anxiety SCL-6 depression Whiteley-7 health anxiety SF-36 Physical functioning Bodily pain General health Mental health Social functioning Vitality Role-physical† Role-emotional‡ CSQ Diverting attention Coping self-statements Praying or hoping Reinterpreting pain Catastrophizing Ignoring pain Increasing activities Experience of control

Patients

Healthy controls

Median; 25–75th percentile; range

Median; 25–75th percentile; range

4; 3–7; 1–12 1; 0–2; 0–4 1; 0–2; 0–6 1; 0–3; 0–4

0; 0–0; 0–3 0; 0–0; 0–2 0; 0–0; 0–1 0; 0–0; 0–3

90; 65–65; 20–100 62; 32–72; 0–88 53.5; 32.5–61; 10–82 68; 56–72; 32–92 75; 62.5–87.5; 25–100 40; 25–50; 10–75 75; 0–100; 0–100 66.7; 33.3–100; 0–100

100; 100–100;85–100 84; 84–100;51–100 90; 82–96; 72–100 92; 84–96; 72–100 100; 100–100; 87.5–100 80: 75–85; 55–85 100; 100–100; 100–100 100; 100–100; 33.3–100

1.8; 1–2.7; 0.8–4.3 3.1; 1.8–4.3; 1–5 1.5; 1–2.7; 0.1–4.8 0.8; 0–1.7; 0–1.2 1.7; 0.3–1.8; 0.8–4.5 2.3; 1.3–3.5; 0.5–4.7 2.6; 1.3–3.7; 0.2–5.7 2.5; 1.5–3.5; 0–5

1; 0–2.5; 0–4.3 3.2; 0.7–4.2; 0–5.8 0.5; 0–1.7; 0–4 0.17; 0–1; 0–2.5 0; 0–0.3; 0–1.2 2; 0.7–3; 0–4.7 1.8; 0.5–2.8; 0–5 5; 4.5–5.5; 0–6

VAS Discomfort Pain Sadness/depression Anxiety Headache Fatigue Neg. cogn. present§ Neg. cogn. future¶ Stress

Mean (s)

Mean (s)

2.36 (2.48) 2.63 (2.57) 0.64 (1.04) 0.09 (0.29) 1.50 (2.58) 3.27 (2.78) 2.73 (2.45) 1.76 (2.21) 2.18 (2.20)

0.16 (0.37) 0.08 (0.28) 0.12 (0.44) 0.20 (0.41) 0.24 (0.72) 0.84 (0.94) 0.60 (0.82) 0.16 (0.47 0.64 (0.76)

Mann–Whitney Z 5.97∗∗ 3.95∗∗ 3.82∗∗ 3.94∗∗ 4.57∗∗ 4.47∗∗ 5.58∗∗ 4.97∗∗ 4.77∗∗ 5.59∗∗ 4.90∗∗ 3.30∗∗ 1.57 1.07 2.70∗∗ 1.53 4.01∗∗ 1.20 2.00∗ 4.32∗∗ 4.03∗∗ 4.619∗∗ 2.34∗ 1.04 2.10∗ 3.40∗∗ 2.92∗∗ 3.42∗∗ 3.10∗∗

s, standard deviation. †Limitations in usual role activities because of physical problems. ‡Limitations in usual role activities because of emotional problems. §Negative cognitions about the impact of condition on present situation. ¶Negative cognitions about the impact of condition on future situation. ∗P0.05; ∗∗P0.01.

Somatization and neuropsychological functioning

Current physical and psychological distress and neuropsychological functioning

To examine how patients’ scores on the SCL Somatization subscale related to performance on each of the neuropsychological tests, a set of correlation coefficients was computed (Table 3). We found no relationship between Somatization and performance on tests of verbal ability, executive function, perceptual organization, and verbal and visual memory. However, high scores on Somatization were significantly associated with poor performance on tests of attention/working memory and psychomotor speed.

High ratings of current pain were significantly associated with poorer performance on neuropsychological tests of all cognitive domains except verbal and visual memory (Table 3). The strongest relationships were found between pain and verbal ability, psychomotor speed, and attention/working memory. High ratings of physical discomfort and headache were significantly associated with poor performance on tests in the domains of psychomotor speed, attention/working memory and perceptual organization (data not shown). With respect to items related to

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NORD J PSYCHIATRY·EARLY ONLINE·2010

SOMATIZATION,


Table 2. Neuropsychological test scores for patients and healthy controls, effect sizes and group differences after control for education level.


Neuropsychological test Verbal IQ Performance IQ Full IQ Verbal ability Information Vocabulary Comprehension Similarities Psychomotor speed Digit Symbol Trail Making Test A§ d2-Test Attention/Working memory Digit Span Digit Span Forward Digit Span Backward Arithmetic Executive function Trail Making Test B§ Short Category Test§ COWA Perceptual organization Block Design Picture Completion Picture Arrangement Object Assembly Verbal and visual memory WMS-R Logical memory, immediate Logical memory, delayed Visual Reproduction, immediate Visual Reproduction, delayed AVLT Sum score list A Recall of interference list B Retention list A after interference Delayed recall list A Delayed recognition list A Delayed recognition list B

Patients mean score (s; range)†

Controls mean score (s; range)

Cohen’s d

Adjusted difference (95% CI)‡

93.2 (11.3; 76–118)∗∗ 104.2 (12.7; 81–122)∗∗ 97.7 (12.7; 78–119)∗∗

105.6 (11.5; 79–124) 115.4 (11.9; 94–134) 110.6 (11.4; 85–130)

1.09 0.91 1.08

7.7 (14.0; 1.4)∗ 8.2 (15.8; 0.68)∗ 8.6 (15.5; 1.7)∗

0.90 0.90 0.96 1.13

1.1 1.3 1.7 1.8

0.85 0.70 0.84

1.3 (2.7; 0.1) 3.3 (1.2; 7.6) 37.4 (87.8; 13.0)

8.5 (1.7; 5–13) 6.6 (1.6; 4–11) 6.4 (1.6; 3–9) 11.2 (3.6; 6–19)

0.67 0.28 0.65 0.77

0.8 (2.4; 0.4) 0.3 (1.3; 0.7) 0.6 (1.7; 0.4) 1.8 (3.6; 0.1)

71.7 (27.3; 43–152)∗ 27.3 (14.4; 5–51) 36.9 (12.1; 11–60)∗

56.9 (17.5; 34–98) 19.6 (12.6; 4–54) 46.6 (13.1; 26–73)

0.65 0.57 0.77

10.6 (3.6; 24.7) 6.2 (2.3; 14.8) 6.2 (13.8; 1.4)

10.7 (2.5; 6–15)∗∗ 10.2 (2.3; 5–14) 10.4 (2.8; 5–15) 10.0 (2.7; 5–15)∗

13.6 (2.7; 8–19) 10.7 (2.4; 6–17) 11.1 (2.7; 7–17) 11.8 (2.9; 7–18)

1.08 0.21 0.26 0.64

2.6 (4.3; 1.0)∗∗ 0.2 (1.7; 1.3) 0.3 (2.0; 1.4) 1.8 (3.6; 0.1)

25.3 (6.7; 14–36) 21.8 (6.2; 6–33) 34.1 (6.8; 21–41) 27.9 (9.3; 2–40)

27.6 (5.9; 14–37) 24.5 (6.4; 11–36) 34.8 (5.7; 18–40) 33.0 (7.4; 17–49)

0.40 0.43 0.00 0.61

–2.2 (6.0; 1.5) –2.1 (6.1; 2.0) 0.7 (3.3; 4.6) 4.3 (9.6; 1.0)

49.2 (10.9; 22–65)∗ 5.0 (1.6; 2–8)∗∗ 10.7 (3.3; 0–15)∗ 10.2 (4.1; 0–15)∗ 12.7 (3.3; 0–15) 7.7 (4.1; 0–14)

55.4 (9.5; 34–71) 6.7 (2.2; 2–12) 12.4 (2.4; 6–15) 12.4 (3.0; 4–15) 13.8 (1.5; 10–15) 8.0 (2.9; 2–15)

0.61 0.91 0.60 0.60 0.46 0.09

4.4 (–10.8; 2.0) –1.3 (–2.5; 0.1)∗ –1.5 (3.3; 0.4) –1.7 (4.0; 0.6) 0.9 (–2.5; 0.7) 6.7 (–2.9; 1.5)

9.1 (2.3; 5–14)∗∗ 8.6 (2.4; 6–13)∗∗ 10.1 (2.6; 6–15)∗∗ 8.9 (2.8; 3–14)∗∗ 9.2 (2.4; 5–13)∗ 30.1 (8.3; 21–60)∗∗ 405.5 (102.1; 214–568)∗ 7.2 (2.2; 3–12)∗ 6.2 (1.6; 3–10) 5.3 (2.0; 2–9)∗ 9.0 (2.4; 6–17)∗∗

11.1 10.8 12.5 11.9

(2.2; (2.4; (2.3; (2.5;

6–16) 7–17) 8–16) 6–15)

11.2 (2.3; 7–17) 25.1 (5.9; 14–38) 483.6 (85.3; 313–598)

(2.3; (2.6; (3.2; (3.2;

0.2)∗ 0.1)∗ 0.2)∗ 0.4)∗

s, standard deviation; CI, confidence interval; COWA, Controlled Oral Word Association; WMS-R, Wechsler Memory Scale—Revised; AVLT, Auditory Verbal Learning Test. †P-values indicate significant differences between test scores of patients and healthy controls. ‡Difference in test scores between patients and healthy controls, adjusted for years of education using linear regression analysis, with 95% confidence interval (CI). §Positive correlation coefficients indicate a negative association between test performance and SCL score, and vice versa. ∗P0.05; ∗∗P0.01.

current psychological distress, i.e. sadness/depression, anxiety, fatigue, stress and negative cognitions about the impact of the condition on present and future situation, there were very few significant associations with poor test performance (data not shown). Notably, we find no association between patients ’ experience of sadness/ depression and poor test performance. Correlation coefficients describing the relationship between SCLdepression/SCL-anxiety and neuropsychological test performance are listed in Table 3 and show no significant associations. NORD J PSYCHIATRY·EARLY ONLINE·2010

Somatization and coping To examine how patients’ Somatization scores relate to their use of coping strategies, correlation coefficients for Somatization and each of the CSQ subscales were calculated. Only one CSQ subscale, namely Increasing behavioural activities, correlated significantly with Somatization (Spearman’s rho 0.51; P 0.02).

Coping and neuropsychological functioning Correlation analyses show that patients’ use of Increasing behavioural activities, the coping strategy associated with

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N. M. HALL ET AL

Table 3. Correlations of patients’ neuropsychological test scores with Symptom Checklist 90-Revised subscales SCL-somatization, SCL-depression, SCL-anxiety, visual analogue scale (VAS) Pain and Coping Strategies Questionnaire (CSQ) Increasing behavioural activities.


Neuropsychological test Verbal IQ Performance IQ Full IQ Verbal ability Information Vocabulary Comprehension Similarities Psychomotor speed Digit Symbol Trail Making Test A† d2-Test Attention/Working memory Digit Span Digit Span Forward Digit Span Backward Arithmetic Executive function Trail Making Test B† Short Category Test† COWA Perceptual organization Block Design Picture Completion Picture Arrangement Object Assembly Verbal and visual memory WMS-R Logical memory, immediate Logical memory, delayed Visual Reproduction, immediate Visual Reproduction, delayed AVLT Sum score list A Recall of interference list B Retention list A after interference Delayed recall list A Delayed recognition list A Delayed recognition list B

Increasing behavioural activities

Somatization

Depression

Anxiety

Pain

0.29 0.32 0.33

0.04 0.23 0.11

0.11 0.20 0.17

0.67∗∗ 0.67∗∗ 0.74∗∗

0.67∗∗ 0.41 0.65∗∗

0.26 .04 0.16 0.21

0.08 0.39 0.17 0.07

0.02 0.55 0.33 0.05

0.59∗∗ 0.48∗ 0.63∗∗ 0.54∗∗

0.53∗ 0.51∗ 0.65∗∗ 0.60∗∗

0.74∗∗ 0.36 0.35

0.07 0.13 0.08

0.02 0.28 0.08

0.71∗∗ 0.53∗ 0.64∗∗

0.53∗ 0.55∗∗ 0.45∗

0.46∗ 0.56∗∗ 0.32 0.15

0.02 0.20 0.11 0.18

0.02 0.11 0.08 0.06

0.68∗∗ 0.36 0.71∗∗ 0.42

0.71∗∗ 0.84∗∗ 0.73∗∗ 0.21

0.20 0.24 0.25

0.04 0.01 0.07

0.18 0.16 0.16

0.49∗ 0.33 0.34

0.66∗∗ 0.27 0.28

0.26 0.05 0.24 0.16

0.06 0.33 0.18 0.09

0.09 0.24 0.14 0.13

0.53∗∗ 0.43 0.45∗ 0.43∗

0.26 0.33 0.23 0.37

0.09 0.00 0.15 0.15

0.14 0.16 0.07 0.22

0.16 0.34 0.08 0.31

0.15 0.31 0.34 0.15

0.04 0.07 0.36 0.08

0.04 0.17 0.04 0.06 0.06 0.31

0.07 0.07 0.08 0.11 0.07 0.10

0.39 0.39 0.24 0.12 0.26 0.18

0.25 0.03 0.07 0.21 0.21 0.17

0.25 0.31 0.11 0.30 0.32 0.40

COWA, Controlled Oral Word Association; WMS-R, Wechsler Memory Scale—Revised; AVLT, Auditory Verbal Learning Test. correlation coefficients indicate a negative association between test performance and SCL score, and vice versa. ∗P 0.05; ∗∗P 0.01. †Positive

high Somatization scores, was strongly associated with low performance on all neuropsychological tests of verbal ability and psychomotor speed and on Digit span and TMT B (Table 3). There was no association between Increasing behavioural activities and performance on tests of perceptual organization and verbal and visual memory. Catastrophizing, which was also used significantly more often by patients than by healthy controls, was not associated with performance on any of the neuropsychological tests. Praying or hoping, also applied more by patients than by healthy controls, was only associated with poor

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performance on Digit span (Spearman’s rho 0.46; P 0.05). There was no association between ratings of Control over pain and test performance.

Discussion The results of the present study show that patients with MFS scored lower than controls on most subtests on the domains of verbal ability, psychomotor speed, attention/ working memory and executive function. Much of this difference could be accounted for by differences in level NORD J PSYCHIATRY·EARLY ONLINE·2010


SOMATIZATION,

of education between the two groups and if we control for verbal ability, virtually no significant difference remains. In patients, a high score on the Somatization subscale was associated with poor performance on tests of psychomotor speed and attention, and with more use of a coping strategy, which aims at distracting attention from pain by increasing behavioural activities. Patients’ use of this coping strategy was associated with low performance on tests of verbal ability, psychomotor speed, attention/working memory and executive function. Finally, while a high level of current physical distress predicted poor performance on many subtests, current psychological distress was unrelated to neuropsychological test performance.

Relationship between somatization and neuropsychological functioning One possible explanation for the co-occurrence of somatic and cognitive symptoms is based on the idea that functional somatic symptoms are bodily alarm signals in response to perceived stress (1). Stress reactions also include cognitive symptoms (34) and cognitive complaints could therefore be seen as functional symptoms parallel to physiological manifestations of stress. In a similar vein, chronic bodily and cognitive symptoms may be the result of allostatic load, the wear and tear on the body and brain by repeated exposure to stress hormones. Brain areas that are particularly affected by stress hormones are the hippocampus, which is involved in encoding and retrieval of new information, and the prefrontal cortex, associated with working memory and executive control (35). If cognitive symptoms can be explained by stress or allostatic load, we would expect a poorer performance on tests of memory and executive functions in patients scoring high on somatization. However, what we found was a relationship between somatization and the more basic cognitive functions of attention and psychomotor speed. The correlational nature of our data does not allow for causal conclusions regarding these associations. Thus, it is not clear whether a reduction in these abilities was present before the development of functional somatic symptoms, or whether disturbed cognition is caused by, or part of, the functional disorder.

Current distress and neuropsychological functioning An alternative, or supplementary, view on the relationship between functional somatic symptoms and neuropsychological functioning is related to the notion of cognitive load (33), which refers to the total amount of mental activity imposed on working memory at a given time. Worry and self-concern as well as the monitoring of symptoms add to cognitive load and may therefore limit the attentional resources available for information processing (26;56). However, it is not clear whether psychological and physical NORD J PSYCHIATRY·EARLY ONLINE·2010


distress directly influence cognitive functioning or whether these aspects merely co-occur. Therefore, controlling for pain and psychological variables when investigating the cognitive ability of patients with functional somatic symptoms may conceal real differences between patients and controls. If cognitive load can, indeed, explain the neuropsychological test performance of MFS patients, we would expect high ratings of physical and psychological distress to be related to poor performance on neuropsychological tests. What we found was a strong relationship between physical distress and neuropsychological test performance. In contrast, we only found sporadic associations between psychological distress and neuropsychological functioning (see similar finding by Park et al.; 23). The fact that cognitive functioning is much more closely related to physical than to psychological distress, although the latter is clearly present in our patient group, suggests that the relationship between pain and physical discomfort and cognitive functioning cannot be explained in terms of cognitive load alone.

Coping with pain and physical discomfort The only coping strategy for which we found a significant association with severity of somatization was Increasing behavioural activities, a strategy by which attention is directed away from pain and physical discomfort through activities such as watching TV, reading, shopping, etc. Increasing behavioural activities is an active coping strategy and active coping is usually considered beneficial (57). However, increasing behavioural activities is also an avoidant strategy because it does not involve active problem solving or advance the patients’ understanding of bodily symptoms. Although it has been shown that avoidant coping strategies are adaptive when dealing with acute pain, chronic pain patients benefit more from attentional than from avoidant coping (58, 59). In support of our suggestion that Increasing behavioural activities is not adaptive when coping with chronic pain, Keefe & Williams (36) found that use of this strategy was related to a high pain level in chronic pain patients. Furthermore, a prospective study of the effect of pain coping strategies on disability in whiplash patients (38) found that Increasing behavioural activities correlated positively with disability scores at 6 months and (even more) at 1-year follow-up but not in the acute phase. In the present study, frequent use of Increasing behavioural activities was associated with poor performance on neuropsychological tests of verbal ability, psychomotor speed, attention/working memory and executive function. The relationship between Increasing behavioural activities and the domains of psychomotor speed and attention/ working memory may be explained by the mutual association with somatization. Given that there was no association between somatization and verbal ability or executive function, our findings suggest that poor performance on

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these domains is associated with an excessive use of Increasing behavioural activities. It has been shown that use of pain-related coping strategies is mediated by educational level (39), and Holm and colleagues (60) suggest that coping strategies may be a mediating factor in the relationship between education and health. Since neuropsychological test performance is related to educational level, our results support this proposal and suggest that reduced verbal and executive skills are associated with maladaptive pain coping.


Limitations It was our intention to match MFS patients to healthy controls with similar age, gender and educational background. However, the demographical properties of the individuals who responded to our advertisement in the local paper unfortunately did not allow us to match for educational level. Future studies should include a larger number of patients with functional somatic symptoms and a control group matched on education. An additional control group with a known medical disorder could supply information as to whether the associations between neuropsychological test performance, coping and symptoms suggested by this study are specific to patients with MFS. The results of the present explorative study have emerged from multiple tests and a correction for multiple comparisons has not been applied. Until new, more focused studies have corroborated our results, the present findings should therefore be considered tentative.

Conclusion The results of the present study show that a high level of somatization is associated with an impaired functioning in the cognitive domains of attention and psychomotor speed. Also, based on our results, we suggest that functional somatic symptoms are maintained or aggravated by an avoidant coping style in which attention is directed away from bodily signals through an increase in behavioural activities, and that an excessive use of this coping style is related to by poor verbal and executive abilities. Based on these findings, we suggest that therapeutic intervention for patients with MFS should include teaching patients to use a broader array of coping strategies, including cognitive strategies focused on the interpretation of the pain experience, control of the amount of attention given to bodily experiences and active pain management. Acknowledgements—This work was supported by grants from the Danish Medical Research Council, Eli Lilly’s Research in Psychiatry Fund, and Fund for Research in Mental Disorders at Aarhus University.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

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