Multiple modes of impulsivity in Parkinson's disease.

Cognitive problems are a major factor determining quality of life of patients with Parkinson's disease. These include deficits in inhibitory control, ranging from subclinical alterations in decision-making to severe impulse control disorders. Based on preclinical studies, we proposed that Parkinson's disease does not cause a unified disorder of inhibitory control, but rather a set of impulsivity factors with distinct psychological profiles, anatomy and pharmacology. We assessed a broad set of measures of the cognitive, behavioural and temperamental/trait aspects of impulsivity. Sixty adults, including 30 idiopathic Parkinson's disease patients (Hoehn and Yahr stage I-III) and 30 healthy controls, completed a neuropsychological battery, objective behavioural measures and self-report questionnaires. Univariate analyses of variance confirmed group differences in nine out of eleven metrics. We then used factor analysis (principal components method) to identify the structure of impulsivity in Parkinson's disease. Four principal factors were identified, consistent with four different mechanisms of impulsivity, explaining 60% of variance. The factors were related to (1) tests of response conflict, interference and self assessment of impulsive behaviours on the Barrett Impulsivity Scale, (2) tests of motor inhibitory control, and the self-report behavioural approach system, (3) time estimation and delay aversion, and (4) reflection in hypothetical scenarios including temporal discounting. The different test profiles of these four factors were consistent with human and comparative studies of the pharmacology and functional anatomy of impulsivity. Relationships between each factor and clinical and demographic features were examined by regression against factor loadings. Levodopa dose equivalent was associated only with factors (2) and (3). The results confirm that impulsivity is common in Parkinson's disease, even in the absence of impulse control disorders, and that it is not a unitary phenomenon. A better understanding of the structure of impulsivity in Parkinson's disease will support more evidence-based and effective strategies to treat impulsivity.

"Frontal systems" behaviors in comorbid human immunodeficiency virus infection and methamphetamine dependency.

Human immunodeficiency virus (HIV) infection and methamphetamine (MA) dependence are associated with neural injury preferentially involving frontostriatal circuits. Little is known, however, about how these commonly comorbid conditions impact behavioral presentations typically associated with frontal systems dysfunction. Our sample comprised 47 HIV-uninfected/MA-nondependent; 25 HIV-uninfected/MA-dependent; 36 HIV-infected/MA-nondependent; and 28 HIV-infected/MA-dependent subjects. Participants completed self-report measures of "frontal systems" behaviors, including impulsivity/disinhibition, sensation-seeking, and apathy. They also underwent comprehensive neurocognitive and neuropsychiatric assessments that allowed for detailed characterization of neurocognitive deficits and comorbid/premorbid conditions, including lifetime Mood and Substance Use Disorders, Attention-Deficit/Hyperactivity Disorder, and Antisocial Personality Disorder. Multivariable regression models adjusting for potential confounds (i.e., demographics and comorbid/premorbid conditions) showed that MA dependence was independently associated with increased impulsivity/disinhibition, sensation-seeking and apathy, and HIV infection with greater apathy. However, we did not see synergistic/additive effects of HIV and MA on frontal systems behaviors. Global neurocognitive impairment was relatively independent of the frontal systems behaviors, which is consistent with the view that these constructs may have relatively separable biopsychosocial underpinnings. Future research should explore whether both neurocognitive impairment and frontal systems behaviors may independently contribute to everyday functioning outcomes relevant to HIV and MA.

Addiction as a stress surfeit disorder.

Drug addiction has been conceptualized as a chronically relapsing disorder of compulsive drug seeking and taking that progresses through three stages: binge/intoxication, withdrawal/negative affect, and preoccupation/anticipation. Drug addiction impacts multiple motivational mechanisms and can be conceptualized as a disorder that progresses from positive reinforcement (binge/intoxication stage) to negative reinforcement (withdrawal/negative affect stage). The construct of negative reinforcement is defined as drug taking that alleviates a negative emotional state. Our hypothesis is that the negative emotional state that drives such negative reinforcement is derived from dysregulation of key neurochemical elements involved in the brain stress systems within the frontal cortex, ventral striatum, and extended amygdala. Specific neurochemical elements in these structures include not only recruitment of the classic stress axis mediated by corticotropin-releasing factor (CRF) in the extended amygdala as previously hypothesized but also recruitment of dynorphin-κ opioid aversive systems in the ventral striatum and extended amygdala. Additionally, we hypothesized that these brain stress systems may be engaged in the frontal cortex early in the addiction process. Excessive drug taking engages activation of CRF not only in the extended amygdala, accompanied by anxiety-like states, but also in the medial prefrontal cortex, accompanied by deficits in executive function that may facilitate the transition to compulsive-like responding. Excessive activation of the nucleus accumbens via the release of mesocorticolimbic dopamine or activation of opioid receptors has long been hypothesized to subsequently activate the dynorphin-κ opioid system, which in turn can decrease dopaminergic activity in the mesocorticolimbic dopamine system. Blockade of the κ opioid system can also block anxiety-like and reward deficits associated with withdrawal from drugs of abuse and block the development of compulsive-like responding during extended access to drugs of abuse, suggesting another powerful brain stress/anti-reward system that contributes to compulsive drug seeking. Thus, brain stress response systems are hypothesized to be activated by acute excessive drug intake, to be sensitized during repeated withdrawal, to persist into protracted abstinence, and to contribute to the development and persistence of addiction. The recruitment of anti-reward systems provides a powerful neurochemical basis for the negative emotional states that are responsible for the dark side of addiction. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.

[The OCD spectrum disorder revisited. Toward a bipolar impulsion-compulsion configuration]. / Spectre du trouble obsessionnel-compulsif revisité à travers un bipôle impulsion-compulsion.

The so-called obsessive-compulsive spectrum disorder (OCD spectrum) is represented by a large variety of clinical entities. There are in general obsessive-compulsive disorder, trichotillomania or Gilles de la Tourette disease among the impulse control disorders, body dysmorphic disorder and hypochondriasis among the somatoform disorders. Updated overview of the OCD spectrum through a bipolar configuration with the impulsion-compulsion (I-C) spectrum, characterized by a failure to resist and control intrusive thoughts associated with repetitive behaviors that seem to be uncontrollable or require considerable efforts to suppress their execution. There are several disrupted processes in the I-C spectrum, including cognitive control, flexibility and behavioural inhibition. All these psychiatric affections demonstrated to share apparent similarities regarding clinical symptomatology, demographic considerations, comorbidity and course pattern, and responses to the serotonine reuptake inhibitors and cognitive behavioural therapy. The concept of I-C spectrum pleads for less categorical and more dimensional approach that seems to be consistently adapted to clinical, genetic, pathophysiology and therapeutic realities.

Measuring "waiting" impulsivity in substance addictions and binge eating disorder in a novel analogue of rodent serial reaction time task.

BACKGROUND: Premature responding is a form of motor impulsivity that preclinical evidence has shown to predict compulsive drug seeking but has not yet been studied in humans. We developed a novel translation of the task, based on the rodent 5-choice serial reaction time task, testing premature responding in disorders of drug and natural food rewards. METHODS: Abstinent alcohol- (n = 30) and methamphetamine-dependent (n = 23) subjects, recreational cannabis users (n = 30), and obese subjects with (n = 30) and without (n = 30) binge eating disorder (BED) were compared with matched healthy volunteers and tested on the premature responding task. RESULTS: Compared with healthy volunteers, alcohol- and methamphetamine-dependent subjects and cannabis users showed greater premature responding with no differences observed in obese subjects with or without BED. Current smokers exhibited greater premature responding versus ex-smokers and nonsmokers. Alcohol-dependent subjects also had lower motivation for explicit monetary incentives. A Motivation Index correlated negatively with alcohol use and binge eating severity. CONCLUSIONS: Premature responding on a novel translation of a serial reaction time task was more evident in substance use disorders but not in obese subjects with or without BED. Lower motivation for monetary incentives linked alcohol use and binge eating severity. Our findings add to understanding the relationship between drug and natural food rewards.

Trait-aggressiveness and impulsivity: role of psychological resilience and childhood trauma in a sample of male prisoners.

BACKGROUND: One of the major challenges for research in the field of human aggression is the need to define the role of personality and trait-like dimensions, such as impulsivity and aggressiveness, in predisposing to violent behavior. AIMS: 1) To determine whether trait- aggressiveness and impulsivity may be associated with socio-demographic, clinical and crime history variables in a sample of male prisoners; 2) to detect any association of those traits with measures of early traumatic experiences and current resilience traits. METHODS: A sample of male prisoners (n = 1356) underwent the Brown-Goodwin Assessment for Lifetime History of Aggression (BGLHA) and the Barratt Impulsivity Scale (BIS). Axis I psychiatric disorders were also assessed. Early traumatic experiences and psychological resilience were detected respectively by the Childhood Trauma Questionnaire (CTQ) and the Connor-Davidson Resilience Scale (CD-RISC). Two non-linear logistic regression models were performed to test for the best predictors of trait-aggressiveness and impulsivity. RESULTS: Subjects with a history of substance use disorders and self-mutilation reported both higher BGLHA and BIS scores. Axis I disorders and suicide attempts were associated with aggressiveness, but not to impulsivity. A consistent correlation was found between BGLHA scores and early traumatic experiences. Resilience was positively correlated to impulsivity but not to aggressiveness scores. CONCLUSIONS: Our results support the view that aggressiveness and impulsivity are two different, albeit related trait-like dimensions of personality, having a different relationship with resilience, and, inferentially, a different impact over the development of psychiatric disorders.

The efficacy of atomoxetine as adjunctive treatment for co-morbid substance use disorders and externalizing symptoms.

BACKGROUND: We examined the effect of atomoxetine supplementation in treated-as-usual patients with alcohol, tobacco and other drug dependence (ATOD) and co-morbid externalizing symptoms (ES). METHOD: Subjects were selected from a substance dependence treatment-cohort and assessed for: (a) high ES counts, (b) maximum prior period of abstinence, (c) quality of life during that period, and (d) shortest time from prior relapse to restarting treatment. Subjects were prescribed atomoxetine and followed up to their first relapse. RESULTS: Out of 262 subjects screened during the study period (March-April 2008), 18 subjects who fulfilled eligibility criteria were recruited. All subjects were male, with early onset of substance dependence to at least two substances. Atomoxetine treatment led to significant treatment benefits: ES reduction, longer abstinence, shorter turnaround time and better quality of life. CONCLUSIONS: Atomoxetine has a potential role in the treatment of early onset ATOD patients with ES, as an adjuvant to the standard treatment.

Relationship between anhedonia and impulsivity in schizophrenia, major depression and schizoaffective disorder.

BACKGROUND: Anhedonia and impulsivity are prominent symptoms of many psychiatric disorders and may indicate worse prognosis, notably in schizophrenia and major depression. Despite the convergence of negative outcomes from both dimensions, the relationship between anhedonia and impulsivity in psychiatric disorders has been seldom directly assessed. The objective of the present study is to examine the correlations between anhedonia and impulsivity in three diagnostic groups: major depression, schizophrenia and schizoaffective disorder. SAMPLING AND METHODS: 121 outpatients (Mansoura University Hospital, Egypt) with major depressive disorder (N=29), schizophrenia (N=59), and schizoaffective disorder (N=33), were assessed and responded to the Beck Depression Inventory, Barrat's Impulsivity Scale-11, and Chapman's Social and Physical Anhedonia Scales. RESULTS: Physical and social anhedonia scores were negatively correlated to impulsivity scores in major depression patients. Conversely, higher scores in physical and social anhedonia predicted higher impulsivity scores in schizophrenia. No correlations between impulsivity and anhedonia were evidenced among schizoaffectives. CONCLUSION: The relationship between self-reported physical and social anhedonia and impulsivity is diagnosis-specific.

[Impulse control in addiction: a translational perspective]. / Impulsregulatie en verslaving: een translationeel onderzoek.

BACKGROUND: Impulsivity is a hallmark of addiction and predicts treatment response and relapse. Impulsivity is, however, a complex construct. Translational cross-species research is needed to give us greater insight into the neurobiology and the role of impulsivity in addiction and to help with the development of new treatment strategies for improving patients' impulse control. AIM: To review recent evidence concerning the concept of impulsivity and the role of impulsivity in addiction. METHOD: The concept and neurobiology of impulsivity are reviewed from a translational perspective. The role of impulsivity in addiction and implications for treatment are discussed. RESULTS: Our recent translational cross-species study indicates that impulsivity is made up of several, separate independent features with partly distinct underlying neurobiological substrates. There are also indications that these features make a unique and independent contribution to separate stages of the addiction cycle. CONCLUSION: In addition, the improvement of impulse control is a promising new target area for treatments that could lead to better results. However, those involved in developing new treatment strategies will have to take into account the complexity and multidimensional character of impulsivity.

Development and validation of a fall-related impulsive behaviour scale for residential care.

INTRODUCTION: impulsivity in older people with cognitive impairment has yet to be examined rigorously as a risk factor for falls. The objective of this study was to evaluate the psychometric properties of a new fall-related impulsive behaviour scale (FIBS) for a cognitively impaired population living in residential care. METHODS: one hundred and nine care home residents (84.5 ± 8.3 years) were assessed on the FIBS and a range of behavioural, physical and neuropsychological measures. Participants were then prospectively followed up for falls for 6 months. RESULTS: the internal reliability (Cronbach's α = 0.77) and test-retest reliability (intra-class correlation coefficient = 0.93) of the FIBS were both good. Construct validity was supported by significant correlations between the FIBS and the neuropsychiatric inventory (r = 0.43, P < 0.001), wandering (r = 0.33, P = 0.001) and global cognition (r = -0.2, P = 0.04). Compared with residents with FIBS scores <1, those with FIBS scores of ≥ 1 were nearly three times more likely to fall in the following 6 months, AOR = 2.92 (95% CI: 1.03-8.29). CONCLUSION: the FIBS is a simple, valid and reliable scale for assessing fall-related impulsivity in care home residents and can be recommended for use in this group for both research and clinical purposes.

Impaired decisional impulsivity in pathological videogamers.

BACKGROUND: Pathological gaming is an emerging and poorly understood problem. Impulsivity is commonly impaired in disorders of behavioural and substance addiction, hence we sought to systematically investigate the different subtypes of decisional and motor impulsivity in a well-defined pathological gaming cohort. METHODS: Fifty-two pathological gaming subjects and age-, gender- and IQ-matched healthy volunteers were tested on decisional impulsivity (Information Sampling Task testing reflection impulsivity and delay discounting questionnaire testing impulsive choice), and motor impulsivity (Stop Signal Task testing motor response inhibition, and the premature responding task). We used stringent diagnostic criteria highlighting functional impairment. RESULTS: In the Information Sampling Task, pathological gaming participants sampled less evidence prior to making a decision and scored fewer points compared with healthy volunteers. Gaming severity was also negatively correlated with evidence gathered and positively correlated with sampling error and points acquired. In the delay discounting task, pathological gamers made more impulsive choices, preferring smaller immediate over larger delayed rewards. Pathological gamers made more premature responses related to comorbid nicotine use. Greater number of hours played also correlated with a Motivational Index. Greater frequency of role playing games was associated with impaired motor response inhibition and strategy games with faster Go reaction time. CONCLUSIONS: We show that pathological gaming is associated with impaired decisional impulsivity with negative consequences in task performance. Decisional impulsivity may be a potential target in therapeutic management.

Impulsivity in binge eating disorder: food cues elicit increased reward responses and disinhibition.

BACKGROUND: Binge eating disorder (BED) represents a distinct eating disorder diagnosis. Current approaches assume increased impulsivity to be one factor leading to binge eating and weight gain. We used eye tracking to investigate both components of impulsivity, namely reward sensitivity and rash-spontaneous behaviour towards food in BED for the first time. METHODS: Overweight and obese people with BED (BED+; n = 25), without BED (BED-; n = 26) and healthy normal-weight controls (NWC; n = 25) performed a free exploration paradigm measuring reward sensitivity (experiment 1) and a modified antisaccade paradigm measuring disinhibited, rash-spontaneous behaviour (experiment 2) using food and nonfood stimuli. Additionally, trait impulsivity was assessed. RESULTS: In experiment 1, all participants located their initial fixations more often on food stimuli and BED+ participants gazed longer on food stimuli in comparison with BED- and NWC participants. In experiment 2, BED+ participants had more difficulties inhibiting saccades towards food and nonfood stimuli compared with both other groups in first saccades, and especially towards food stimuli in second saccades and concerning sequences of first and second saccades. BED- participants did not differ significantly from NWC participants in both experiments. Additionally, eye tracking performance was associated with self-reported reward responsiveness and self-control. CONCLUSIONS: According to these results, food-related reward sensitivity and rash-spontaneous behaviour, as the two components of impulsivity, are increased in BED in comparison with weight-matched and normal-weight controls. This indicates that BED represents a neurobehavioural phenotype of obesity that is characterised by increased impulsivity. Interventions for BED should target these special needs of affected patients.

Impulsivity, cognitive function, and their relationship in heroin-dependent individuals.

There is mixed evidence concerning cognitive function and heroin dependence. In this study, abstinent heroin-dependent individuals (n = 86) and age- and sex-matched non-drug-using controls (n = 88) were compared on self-report measures of impulsivity and computerized assessments of cognitive function. Abstinent heroin-dependent individuals reported greater motor impulsivity and experience seeking and showed functional weaknesses in cognitive ability, including impulsivity and distractibility (d = 0.28 to 0.49), but not decision making or working memory. Self-reported impulsivity was uncorrelated with cognitive function. These results suggest underlying brain-related factors in heroin dependence and have implications for therapeutic intervention.

[Impulsive-compulsive behaviours in a German Parkinson's disease outpatient sample]. / Impulsiv-zwanghafte verhaltensstörungen in einer deutschen stichprobe ambulant versorgter Parkinson-patienten.

BACKGROUND: Impulsive-compulsive behaviours (ICBs) are frequent complications of Parkinson's disease (PD), associated with treatment by dopamine agonists (DAs). These include impulse control disorders (ICDs), repetitive behaviour (RB) and the dopamine-dysregulation syndrome (DDS). METHODS: A subsample of 72 patients of a large longitudinal study (n = 739) was screened with the Questionnaire for Impulsive-Compulsive Disorders in Parkinson's disease (QUIP). Results were associated with socio-demographic, clinical and neuropsychological parameters. RESULTS: A large proportion of the sample reported ICBs (60%), RBs were most frequent (47 %). Patients with ICBs consumed higher doses of DAs (343 ± 177 mg vs. 390 ± 153 mg; p < 0.01). Pramipexole was associated with RB but not ICDs (273 ± 225 mg and 53 ± 106 mg vs. 151 ± 209 mg in patients without ICB). Patients with ICDs reported more dyskinesias (UPDRS IV: 1.78 ± 1.6 vs. 0.55 ± 1.1 points; p = 0.012) and patients with multiple ICBs a longer duration of PD (9.3 ± 5.0 vs. 6.2 ± 4.0 years; p = 0.026) and worse quality of life (PDQ39: 29.9 ± 13.8 vs. 20.3 ± 13.4 points; p = 0.036) compared to patients without any ICB. CONCLUSIONS: ICBs are frequent even in outpatients with moderate duration and severity of PD and associated with DA dose. Because of possible serious psychosocial consequences, detecting and managing them is of high importance.

Impulsiveness in patients with bulimia nervosa: electrophysiological evidence of reduced inhibitory control.

OBJECTIVES: Bulimia nervosa (BN) is associated with a deficit of self-regulatory control and impulsivity. The present study aimed to clarify whether an impaired inhibitory control due to hyperarousal underlies impulsivity in BN subjects. METHODS: Event-related potentials (ERPs) were recorded in 17 female patients with BN and 17 healthy controls during a three-tone oddball task. ERP components related to inhibition of irrelevant distractor stimuli, as well as effortful processing, were analyzed. Standardized low-resolution electromagnetic tomography (sLORETA) was used to assess ERP source activity. RESULTS: Compared to healthy controls, BN patients showed reduced amplitude and shorter latency of the N200 (N2), increased amplitude and shorter latency of the target slow wave (SW), and higher amplitude of the P300 for distractor stimuli (P3a) and for targets (P3b). sLORETA showed the following: (1) higher activity of the P3a generators in the left parietal cortex, bilateral precuneus and right frontal and anterior cingulate for distractor stimuli and (2) lower activity of the SW generators in the left medial frontal gyrus, bilateral superior frontal, anterior cingulate and cuneus for target stimuli. The reduction of the N2 latency was associated with the Barratt scores for impulsiveness. CONCLUSIONS: The observed electrophysiological abnormalities suggest a condition of hyperarousal, with impaired suppression of irrelevant stimuli due to abnormal cortical activation and reduced signal-to-noise ratio. Our findings point to functional abnormalities within a neural system that subserves attention and self-regulatory control, which may contribute to impulsive behaviors in BN.

Is there an empirical link between impulsivity and suicidality in bipolar disorders? A review of the current literature and the potential psychological implications of the relationship.

OBJECTIVES: Suicide is highly prevalent among individuals with bipolar disorder and understanding the factors that increase risk for suicide may help to develop targeted interventions to prevent attempts. Impulsivity is thought to be an influential factor associated with suicidality and is also discussed as a key construct of bipolar disorder. The aim of this paper was to systematically review the current evidence to examine the association between impulsivity and suicidality in bipolar disorder. METHODS: PsycInfo, Medline, and Web of Knowledge databases were searched for articles published up until March 2012. Papers were included if they assessed an adult sample of individuals with bipolar disorders, focused on suicidality (ideation with intent to die, suicide attempts, or completion), and used a validated measure to determine impulsivity. RESULT: Sixteen papers were identified. Contrary to widespread belief, we found (i) a very inconsistent picture of results including positive, negative, and insignificant associations between impulsivity and suicidality; and (ii) some studies do not take into account important aspects such as state-trait or measurement issues. CONCLUSIONS: The link between suicidality and impulsivity is less straightforward than often assumed. Drawing clear conclusions about the association is hampered by factors such as inconsistencies in defining suicidality, measuring impulsivity, and differentiating between impulsivity as a personality trait and impulsivity as a state (e.g., a consequence of substance use or premeditation of the attempt). We suggest that the association is less direct and that psychological models (e.g., Joiner's theory of suicidality) can help foster a more in-depth understanding regarding the relationship.

Untreated major depressive disorder with and without atypical features: a clinical comparative study.

AIMS AND METHOD: A comparative study of major depression with and without atypical features (as per DSM IV TR criteria) was planned to assess illness characteristics, resulting dysfunction and co-morbidities, which can have important implications in its management. Serially, 107 newly registered patients with depression not taking any treatment for at least a month were included. Patients with psychotic features in present or past, known bipolar disorder and likely organic aetiology were excluded. They were interviewed using SCID I (Structured clinical interview for DSM IV axis I disorders). Impulsiveness, suicidal ideation and functioning in various spheres was also assessed and compared between those with and without atypical features. RESULTS: Atypical features were seen in a significant number (55.14%) of patients especially from urban and semi-urban areas. Interpersonal sensitivity and leaden paralysis were the commonest atypical features apart from mood reactivity. Presence of hypersomnia and/or hyperphagia documented in 36 (33.65%) of 107 patients. Comparison of patients with and without atypical features revealed no significant difference in illness characteristics including suicidal ideation. However, they differed in level of impulsiveness and associated psychiatric co-morbidities. Also, deterioration of functioning with rising HDRS was more significant in patients without atypical features. CLINICAL IMPLICATIONS: Presence of atypical features is common in patients with major depressive disorder. These patients should be vigilantly assessed and managed in view of equal morbidity but different co-morbidities like anxiety and soft bipolar disorders than those without atypical features.

Prediction of alcohol and gambling problems in young adults by using a measure of decision making.

OBJECTIVES: Individuals who regularly gamble, regularly consume alcohol, or meet criteria for an alcohol-use disorder or pathological gambling may make riskier decisions on cognitive tasks. What remains unclear in the literature is whether these decision-making deficits precede or result from these addictive behaviors. This study aimed to determine whether risky decision making on a cognitive task is predictive of increasing gambling behaviors and alcohol use. METHODS: Fifty-eight young adults (aged 18-29 years) free from Axis I disorders and reporting no symptoms of at-risk gambling behavior or alcohol consumption, who were participating in a longitudinal study of impulsivity, were grouped as either high-risk decision makers (n = 29) or low-risk decision makers (n = 29) by using the Cambridge Gamble Task. Subjects were assessed at 1-year follow-up to examine gambling frequency, alcohol consumption, at-risk alcohol-use criteria, alcohol-use disorder criteria, at-risk gambling criteria, and pathological gambling criteria. RESULTS: High-risk decision makers were found to be more likely to meet at-risk criteria for alcohol use after 1 year. Decision-making group membership was not significantly correlated with frequency of gambling or development of pathological gambling or alcohol-use disorder over 1 year. CONCLUSIONS: A variable measuring risky decision making on the Cambridge Gambling Task may be able to predict who is more likely to increase alcohol use per session later in life.

Characterization of suicidal behaviour with self-organizing maps.

The study of the variables involved in suicidal behavior is important from a social, medical, and economical point of view. Given the high number of potential variables of interest, a large population of subjects must be analysed in order to get conclusive results. In this paper, we describe a method based on self-organizing maps (SOMs) for finding the most relevant variables even when their relation to suicidal behavior is strongly nonlinear. We have applied the method to a cohort with more than 8,000 subjects and 600 variables and discovered four groups of variables involved in suicidal behavior. According to the results, there are four main groups of risk factors that characterize the population of suicide attempters: mental disorders, alcoholism, impulsivity, and childhood abuse. The identification of specific subpopulations of suicide attempters is consistent with current medical knowledge and may provide a new avenue of research to improve the management of suicidal cases.

Major depressive disorder and impulsive reactivity to emotion: toward a dual-process view of depression.

OBJECTIVE: Dual-process theories of behaviour have been used to suggest that vulnerability to depression involves elevated reactivity to emotions. This study tests that idea, examining self-reported reactivity. DESIGN: Comparison between persons with at least one lifetime episode of major depressive disorder (lifetime MDD) and those without this diagnosis, controlling for symptoms of alcohol use (a potential externalizing confound) and current symptoms of depression (a potential state-dependent confound). METHODS: Undergraduates (N = 120) completed a clinical interview to diagnose lifetime MDD and a series of self-reports bearing on diverse aspects of self-control, including reactivity to emotion. Thirty-four people were diagnosed with lifetime MDD; 86 did not meet criteria for MDD. The groups were then compared on three factors underlying the scales assessing self-control. RESULTS: The MDD group had higher scores than controls on the two factors that reflect impulsive reactivity to diverse emotions, including emotions that are positive in valence. These effects were not explained by associations with either externalizing symptoms or current depressive symptoms. CONCLUSIONS: Reflexive reactivity to emotions characterizes depression, in addition to some externalizing problems, and it may deserve study as a potential trans-diagnostic feature. PRACTITIONER POINTS: Reflexive reactivity to emotions characterizes persons diagnosed with major depressive disorder. Findings suggest desirability of focusing treatment partly on management of reflexive reactions to emotions. LIMITATION: Measures were self-reports, rather than behavioural responses to emotions.