Objective: The understanding of suicidal behavior is incomplete. The stress-diathe- sis model suggests that a deficit in sero- tonergic projections to the ...
Article
Impaired Decision Making in Suicide Attempters Fabrice Jollant, M.S. Frank Bellivier, M.D., Ph.D. Marion Leboyer, M.D., Ph.D. Bernard Astruc, M.D. Stéphane Torres, M.D. Régis Verdier, M.D. Didier Castelnau, M.D. Alain Malafosse, M.D., Ph.D. Philippe Courtet, M.D., Ph.D.
Objective: The understanding of suicidal behavior is incomplete. The stress-diathesis model suggests that a deficit in serotonergic projections to the orbitofrontal cortex is involved in susceptibility to suicidal behavior. The orbitofrontal cortex has been implicated in decision making, a cognitive function dealing with complex choices that may be under serotonergic modulation. In this preliminary study, the authors assessed decision making in suicide attempters. Method: The authors used the Iowa Gambling Task to investigate patients with a history of violent (N=32) or nonviolent (N=37) suicidal behavior, patients suffering from affective disorders with no history of suicidal behavior (N=25), and healthy comparison subjects (N=82). Patients were assessed when they were not suffering from a current axis I disorder. The authors also assessed the correlation of Iowa Gambling Task performance with psychometric measures of impulsivity,
hostility, anger, aggression, and emotional instability. Results: Both groups of suicide attempters scored significantly lower than healthy comparison subjects, and violent suicide attempters performed significantly worse than affective comparison subjects. No significant differences were observed between the groups of suicide attempters or between the two comparison groups. The differences in performance could not be accounted for by age, intellectual ability, educational level, number of suicide attempts, age at first suicide attempt, history of axis I disorder, or medication use. Iowa Gambling Task performances were correlated positively with affective lability and with anger expression but not with impulsivity. Conclusions: Impaired decision making, possibly due to emotional dysfunction, may be a neuropsychological risk factor for suicidal behavior. (Am J Psychiatry 2005; 162:304–310)
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uicide is a major public health concern in most Western countries. Unfortunately, current prevention strategies are based on screening for numerous risk factors, none of which has been shown to have sufficient predictive power (1). A stress-diathesis model was recently constructed (2) to model and expand knowledge concerning the pathophysiology of suicidal behavior. According to this model, only persons with a susceptibility (diathesis) to suicidal behavior are at risk of attempting to take their own lives after exposure to stress. Many studies have provided evidence that the serotonergic system is involved in this susceptibility. Indeed, several studies of suicide attempters or completers have identified specific serotonergic impairments, predominantly in the orbitofrontal cortex and the brainstem (for review, see reference 3). Thus, alterations in the activity of the serotonergic projections to the orbitofrontal cortex appear to be an important component of susceptibility to suicidal behavior. Furthermore, molecular genetic studies have reported associations of suicidal behavior with serotonin-related genes (4–6). Nonreplication (7) may be accounted for by the heterogeneity and multiple causes of suicidal behavior. Neuropsychological traits could be used to increase the homogeneity of suicidal behavior groups in studies.
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A few studies have investigated neuropsychological dysfunction in suicide attempters. Keilp et al. (8) found that depressed suicide attempters presented a deficit in executive functions, which are known to be linked to the prefrontal cortex, independently of the severity of depression. The cognitive function of decision making has been shown to be linked to the orbitofrontal cortex by lesion (9–11) and functional imaging studies (12–15). Damage to the orbitofrontal cortex leads to high-risk, disadvantageous decisions in real life (16, 17). If a lesion is restricted to the orbitofrontal cortex, all classic neuropsychological test results are normal, except those assessing decision making, such as the Iowa Gambling Task (18) and others (10). Moreover, previous studies reported the possible modulation of decision-making functions by the serotonergic system (10, 19). Assuming that the orbitofrontal cortex and the serotonergic system are involved both in this cognitive function and in susceptibility to suicidal behavior, we tested the hypothesis that decision making is impaired in suicide attempters. We also investigated whether Iowa Gambling Task performance was correlated with personality traits that are thought to be linked to the prefrontal cortex, suicidal behavior, and serotonergic dysfunction. Am J Psychiatry 162:2, February 2005
JOLLANT, BELLIVIER, LEBOYER, ET AL.
Method Subjects and Experimental Design Sixty-nine suicide attempters ages 19 to 70 years were included in the study. This study was part of a larger multicenter project on the genetics of suicidal behavior, which was approved by the local research ethics committees. Subjects had to be between 18 and 75 years old, with all four biological grandparents originating from countries in Western Europe. After complete description of the study to the subjects, written informed consent was obtained. A suicide attempt was defined as a self-damaging act carried out with some intent to die and distinguished from other self-destructive types of behavior, such as self-mutilation, noncompliance with medical treatment in severely ill individuals, and the use of substances such as alcohol and tobacco (3). Patients who exhibited only suicidal ideation or who threatened to commit suicide without actually taking action were not included. We characterized the suicide attempts by using the French versions of the Risk Rescue Rating Scale (20), a 10-item scale evaluating the risk (and more precisely, the lethality) and the possibilities of rescue regarding the act, and the Suicidal Intent Scale (21), a 15-item scale assessing the circumstances and expectations relating to the suicide attempt. Lifetime axis I psychiatric diagnoses were made according to the DSM-IV. Diagnostic assessment had been done by experienced psychiatrists (F.B., B.A., S.T., and P.C.) with the French version of the Mini-International Neuropsychiatric Interview (22), medical records, and any other information. All participants were also assessed with the 21-item Hamilton Depression Rating Scale (23) to ensure that they were normothymic at the time of evaluation (score below 7). We assessed intellectual ability using the French version of the National Adult Reading Test (24). We assigned suicide attempters to two groups of similar size that were defined on the basis of the means used in the most serious suicide attempt (25): violent (N=32) or nonviolent (N=37). Violent suicide attempts involved deep cutting (N=8), jumping from heights (N=6), hanging (N=6), electrocution (N=3), jumping in front of a car (N=2), gunshot wounds (N=2), crashing a scooter or a car (N=2), asphyxia with a bag and gas (N=1), immolation by fire (N=1), and drowning (N=1). Nonviolent suicide attempts were drug overdoses (N=33), superficial wrist cutting (N=1), and a combination of drug overdose and superficial wrist cutting (N=1). Two patients who drank detergent were classified as nonviolent attempters. Thirteen of the 34 patients who took drug overdoses required hospitalization in an intensive care unit after their suicide attempts. Two groups of comparison subjects were included after a clinical examination by the experienced psychiatrists we mentioned with the Mini-International Neuropsychiatric Interview: 82 subjects with no personal history of suicide attempt or current pharmacological treatment (healthy comparison subjects) and 25 subjects with no personal history of suicide attempt but a personal history of mood disorder (affective control subjects). Inclusion of the affective control group made it possible to compare suicide attempters with other individuals susceptible to mood and anxiety disorders who were taking medication. All control subjects were between 19 and 69 years old. None of the participants had a neurological disorder.
The Iowa Gambling Task We tested decision-making skills using the computerized version of the Iowa Gambling Task (26). The procedure was identical for all participants and has been described elsewhere (26). Briefly, the subject has to make a choice between four decks of cards (60 cards each). When he or she clicks on a deck, he or she may win or both win and lose money. The goal of the game is to win as much money as possible. The subject does not know that he or she will Am J Psychiatry 162:2, February 2005
pick up a total of 100 cards. The subject also does not know that there are two advantageous decks for which little money is won but even less is lost (resulting in a net gain) and two disadvantageous decks for which a lot of money is won but even more is lost (resulting in a net loss). The subject does not know when he or she will lose money, which creates a feeling of uncertainty. The recording of the choices is made by a computer.
Psychometric Measures Personality traits were assessed by means of self-administered questionnaires: the Barratt Impulsiveness Scale (27), the BussDurkee Hostility Inventory (28), and the Spielberger State-Trait Anger Expression Inventory (29). We used two self-report scales to assess emotional changes: the Affective Intensity Scale (30), which scores the intensity of emotional response, and the Affective Lability Scales (31), which scores various types of affective variation (depression/normal, elation/normal, bipolar [i.e., elation/depression], anxiety/normal, anxiety/depression, and anger/normal). In our analyses, a low score on the scale means high affective lability. We also used the Brown-Goodwin Life History of Aggression (32), a questionnaire concerning lifetime aggression.
Statistical Analysis Choices were classified as advantageous (decks C and D) or disadvantageous (decks A and B). The score is the difference between the number of advantageous and disadvantageous choices. Five intermediate scores were calculated for each subject (blocks of 20 choices), indicating changes in the pattern of choices during the game. A net score (sum of the intermediate scores) was then calculated. Statistical analysis was carried out with SAS software (SAS Institute, Cary, N.C.). Since the Shapiro-Wilks test showed nonnormal distribution for most of the scores, we used nonparametric tests. Significance was set at p
