Platelet monoamine oxidase activity in mentally disordered violent offenders

Detention in Juvenile Correctional Facilities Is Associated with Higher Platelet Monoamine Oxidase B Activity in Males

Juvenile delinquency is related to several biological factors, yet very few vulnerability biomarkers have been identified. Previous data suggest that the enzyme monoamine oxidase B (MAO-B) influences several personality traits linked to the propensity to engage in delinquent behavior. Building on this evidence, we assessed whether conduct disorder (CD), juvenile delinquency adjudications, or detention in a correctional facility were associated with either platelet MAO-B activity or the MAOB rs1799836 polymorphism. The study enrolled 289 medication-free male youths, including 182 individuals detained in a correctional facility (with or without a diagnosis of CD). Of the remaining 107 participants, 26 subjects had a diagnosis of CD, and 81 were mentally healthy controls. Platelet MAO-B activity was determined by spectrophotofluorometry, while MAOB rs1799836 was genotyped using qPCR. Platelet MAO-B activity, corrected for age and smoking, was significantly higher in juvenile detainees (p < 0.001), irrespective of CD diagnosis. MAOB rs1799836 was not associated with platelet MAO-B activity or with detention in a correctional facility, CD diagnosis, or delinquent behavior. These data suggest that detention in a juvenile correctional facility increases platelet MAO-B activity in male adolescents. Future studies are needed to determine the mechanisms and functional significance of MAO-B peripheral elevation in juvenile male detainees.

Aggressive behavior in psychiatric patients in relation to hormonal imbalance (Review)

Aggressive behavior is one of the main characteristics of different psychiatric disorders such as: personality disorders (antisocial personality disorder, borderline personality disorder), schizophrenia, intermittent explosive disorder, post-traumatic stress disorder, bipolar disorder, depression, alcohol/substance induced psychiatric disorders. Epidemiological evidence shows that always there is a higher risk of violence and aggressivity among patients with psychiatric disorders compared with general population. Researchers have tried many times to narrow the theories that can explain such a behavior, starting from models that involve a link between illness and aggression going up to external-environmental factors including the therapeutic relation in the hospital. Even if the majority of studies are centered on intoxications (with alcohol or other substances that potentiate the aggressive behavior) we will highlight another somatic dimension linked with this behavior. In the following review we summarize the hormonal imbalances that have been noted to accompany aggressive behavior in different psychiatric disorders. Several studies have been made starting even at the age of ten corelating hormone cortisol with increase aggression, but patients with psychiatric disorders have a higher sensitivity in linking hormonal imbalance with their behavior.

The role of monoamine oxidase A in aggression: Current translational developments and future challenges

Drawing upon the recent resurgence of biological criminology, several studies have highlighted a critical role for genetic factors in the ontogeny of antisocial and violent conduct. In particular, converging lines of evidence have documented that these maladaptive manifestations of aggression are influenced by monoamine oxidase A (MAOA), the enzyme that catalyzes the degradation of brain serotonin, norepinephrine and dopamine. The interest on the link between MAOA and aggression was originally sparked by Han Brunner's discovery of a syndrome characterized by marked antisocial behaviors in male carriers of a nonsense mutation of this gene. Subsequent studies showed that MAOA allelic variants associated with low enzyme activity moderate the impact of early-life maltreatment on aggression propensity. In spite of overwhelming evidence pointing to the relationship between MAOA and aggression, the neurobiological substrates of this link remain surprisingly elusive; very little is also known about the interventions that may reduce the severity of pathological aggression in genetically predisposed subjects. Animal models offer a unique experimental tool to investigate these issues; in particular, several lines of transgenic mice harboring total or partial loss-of-function Maoa mutations have been shown to recapitulate numerous psychological and neurofunctional endophenotypes observed in humans. This review summarizes the current knowledge on the link between MAOA and aggression; in particular, we will emphasize how an integrated translational strategy coordinating clinical and preclinical research may prove critical to elucidate important aspects of the pathophysiology of aggression, and identify potential targets for its diagnosis, prevention and treatment.

Monoamine oxidase and agitation in psychiatric patients

Subjects with schizophrenia or conduct disorder display a lifelong pattern of antisocial, aggressive and violent behavior and agitation. Monoamine oxidase (MAO) is an enzyme involved in the degradation of various monoamine neurotransmitters and neuromodulators and therefore has a role in various psychiatric and neurodegenerative disorders and pathological behaviors. Platelet MAO-B activity has been associated with psychopathy- and aggression-related personality traits, while variants of the MAOA and MAOB genes have been associated with diverse clinical phenotypes, including aggressiveness, antisocial problems and violent delinquency. The aim of the study was to evaluate the association of platelet MAO-B activity, MAOB rs1799836 polymorphism and MAOA uVNTR polymorphism with severe agitation in 363 subjects with schizophrenia and conduct disorder. The results demonstrated significant association of severe agitation and smoking, but not diagnosis or age, with platelet MAO-B activity. Higher platelet MAO-B activity was found in subjects with severe agitation compared to non-agitated subjects. Platelet MAO-B activity was not associated with MAOB rs1799836 polymorphism. These results suggested the association between increased platelet MAO-B activity and severe agitation. No significant association was found between severe agitation and MAOA uVNTR or MAOB rs1799836 polymorphism, revealing that these individual polymorphisms in MAO genes are not related to severe agitation in subjects with schizophrenia and conduct disorder. As our study included 363 homogenous Caucasian male subjects, our data showing this negative genetic association will be a useful addition to future meta-analyses.

Variation of types of alcoholism: review and subtypes identified in Han Chinese

Alcoholism, as it has been hypothesized, is caused by a highly heterogeneous genetic load. Since 1960, many reports have used the bio-psycho-social approach to subtype alcoholism; however, no subtypes have been genetically validated. We reviewed and compared the major single-gene, multiple-gene, and gene-to-gene interaction studies on alcoholism published during the past quarter-century, including many recent studies that have made contributions to the subtyping of alcoholism. Four subtypes of alcoholism have been reported: [1] pure alcoholism, [2] anxiety/depression alcoholism, [3] antisocial alcoholism, and [4] mixed alcoholism. Most of the important studies focused on three genes: DRD2, MAOA, and ALDH2. Therefore, our review focuses on these three genes.

Neurobiological mechanisms for impulsive-aggression: the role of MAOA

Aggression may be present across a large part of the spectrum of psychopathology, and underlies costly criminal antisocial behaviors. Human aggression is a complex and underspecified construct, confounding scientific discovery. Nevertheless, some biologically tractable subtypes are apparent, and one in particular-impulsive (reactive) aggression-appears to account for many facets of aggression-related dysfunction in psychiatric illness. Impulsive-aggression is significantly heritable, suggesting genetic transmission. However, the specific neurobiological mechanisms that mediate genetic risk for impulsive-aggression remain unclear. Here, we review extant data on the genetics and neurobiology of individual differences in impulsive-aggression, with particular attention to the role of genetic variation in Monoamine Oxidase A (MAOA) and its impact on serotonergic signaling within corticolimbic circuitry.

Neuropsychological function and platelet monoamine oxidase activity levels in type I alcoholic patients

AIMS

To explore neuropsychological function in two differentiated patterns of platelet monoamine oxidase B (MAO B) activity in alcoholic patients.

METHODS

Neuropsychological examination and platelet MAO B activity extracted from blood were collected from 42 alcohol-dependent patients recruited in the alcoholism unit (NETER) of the Psychiatric Service of Santa Maria University Hospital.

RESULTS

Alcoholics presented significantly low levels of platelet MAO B activity, when compared with control subjects; platelet MAO B activity in alcoholics classified as "under average subgroup" showed significant lower scores in the Raven Progressive Matrix and higher scores in hostility dimension, when compared with platelet MAO B activity in "above average subgroup."

CONCLUSIONS

Results suggested platelet MAO B as a trait marker also to type I alcohol-dependent patients and the two observed associations between platelet MAO B activity with neurocognitive measures of executive functions (nonverbal reasoning) and psychopathological dimension such as hostility may support the notion about the effect of platelet MAO B activity in the further development of an impulsive cognitive style.

Monoamine oxidase activity and tri-iodothyronine level in violent offenders with early behavioural problems

The focus is on evaluating the relationships between early behavioural problems and biochemical variables at adult age and their significance for early criminality and violent behaviour in a life perspective. In the present study, using prospective longitudinal data, a sample of males with a history of early criminal behaviour and male controls (n = 103) were investigated concerning (1) teacher-rated behaviours at age 11-14 years; (2) platelet monoamine oxidase (MAO) activity and tri-iodothyronine (T(3)) level at adult age; (3) registered early criminality (11-14 years); (4) records of violent offending up to age 35 years, and (5) interview data on smoking. The main finding was that a combined risk level pattern of low MAO activity and high T(3) level was found significantly more frequently than expected in violent offenders with an early behavioural risk pattern. Furthermore, there was a significant interaction effect between early attention difficulties and smoking on MAO activity, as well as an effect by smoking on MAO activity. The findings are discussed in terms of the possible influence of biological vulnerability to certain behaviours, which in combination with possible childhood stress, enhance the risk for antisocial behaviours and subsequent violence.

Platelet MAO-B, personality, and psychopathology

The article investigates the relationships between platelet monoamine oxidase-B (MAO-B) activity, personality, and psychopathology (Diagnostic and Statistical Manual of Mental Disorders [4th ed.; American Psychiatric Association, 1994] diagnoses. These relationships were assessed in 178 incarcerated male juvenile delinquents. Even after controlling for smoking, the authors found that both Internalizing and Externalizing Psychopathology were negatively related to MAO-B activity. In the final reduced model, novelty seeking fully mediated the relationships between MAO-B and Externalizing Psychopathology but not between MAO-B and Internalizing Psychopathology. It was hypothesized that low platelet MAO-B activity does not directly predispose individuals to psychopathology but is related to specific personality traits, which in turn represent a vulnerability factor for psychopathology. Future studies should help clarify the nature of the relationships between personality, biological markers, and psychopathology.

Personality Characteristics as Risk Indications of Alcohol Use and Violent Behavior in Male and Female Adolescents

Abstract. The present study focused on personality characteristics in adolescent boys (n = 414) and girls (n = 552) in 8th grade with self-reported violent behavior and risky alcohol use. Adolescents with indications of violent behavior and/or risky alcohol use, compared to others, were generally more impulsive, had a stronger need for change and action, were less adjusted and socially conforming, as well as more aggressive. The findings pointed toward a clustering of problem behaviors. Furthermore, adolescents with a combination of violent behavior and alcohol use had more pronounced personality scores than subjects who reported only one of these behaviors. The main finding was that among girls these behaviors appeared to be associated with more deviant levels of the personality characteristics in focus.

Platelet monoamine oxidase activity and psychometric correlates in male violent offenders imprisoned for homicide or other violent acts

Violent behavior has been associated with certain personality traits like poor impulse control, sensation seeking, and monotony avoidance, which predispose to increased risk for violent acts. Low platelet monoamine oxidase (MAO) activity has been found in subjects with such traits, as well as in imprisoned violent offenders. On the other hand, cigarette smoking is expected to inhibit MAO activity. We assessed impulse control, lifetime history of aggression, suicide risk, as well as platelet MAO activity in 82 male offenders (mean age 33.0+/-10.7 years) imprisoned for homicide or other violent acts, and in 54 control male subjects (mean age 35.1+/-6.6 years). General psychopathology was assessed by the Hopkins Symptom Check List (SCL-90) questionnaire. A high rate of smoking (89%),significantly higher than controls (63%), was observed in offenders, but there were no differences in MAO activities among nonsmokers, moderate, or heavy smokers in either group. Offenders showed significantly higher scores in Impulse Control, Past Feelings and Acts of Violence, Suicide Risk and SCL-90 scales. Offenders who had committed other violent acts than homicide had higher scores in the three psychometric scales and in the Depression, Obsessive-Compulsive, Hostility, and Anxiety subscales of the SCL-90, than offenders who had committed homicide. Platelet MAO activity was significantly lower (p=0.01) in the offenders' group (38.1+/-14.4) compared to controls (44.7+/-15.2). The difference could not be attributed to smoking, and seems to be related to personality traits and behaviors that characterize the offenders' group.

Long-term validity of biological markers of psychopathy and criminal recidivism: follow-up 6-8 years after forensic psychiatric investigation

This study is a follow-up investigation of a forensic psychiatric sub-population 6-8 years after forensic psychiatric evaluation. The aim was to examine the long-term validity of biological markers of psychopathy and antisocial behavior over time. Data on criminal records were obtained at follow-up from the National Council for Crime Prevention. Basic data included findings of psychiatric and psychological assessments, as well as values for serum triiodothyronine (T3) and free thyroxin (FT4), and platelet monoamine oxidase (MAO) activity, all obtained during the forensic psychiatric examination. Criminal recidivists at follow-up had higher serum T3 levels than non-recidivists, and much higher values than normal controls, while their levels of free T4 were lower. The T3 levels in criminal recidivists correlated to psychopathy- and aggression-related personality traits as measured by the Karolinska Scale of Personality. In violent recidivists, a remarkably high correlation was noted between T3 levels and Irritability and Detachment, traits that have previously been linked to the dopaminergic system. Stepwise multiple regression analyses confirmed the relationships of T3 levels and platelet MAO activity with personality traits in criminal recidivists. The predictive validity of biological markers of psychopathy, T3 and platelet MAO, measured during forensic psychiatric investigation, is stable over time. The results indicate chronic alterations of the hypothalamic-pituitary-thyroid axis in this group of subjects.

Neither antisocial personality disorder nor antisocial alcoholism is associated with the MAO-A gene in Han Chinese males

BACKGROUND

Recent studies on the genetics of alcoholism have suggested an association between antisocial alcoholism and the MAO-A gene. However, previous studies have failed to include subjects with antisocial personality disorder without alcoholism even though there is a high comorbidity between antisocial personality disorder and alcoholism. Consequently, the finding of an association between the MAO-A gene and alcoholism or antisocial personality disorder seems tenuous. In Taiwan, about 70% of the Han Chinese population have the ADH2*2 allele and 50% show ALDH2*1/*2 or ALDH2*2/*2 genotypes, which offer protection against drinking behavior and the risk of developing alcoholism. Thus, it is possible to recruit individuals with antisocial personality disorder but without alcoholism in Taiwan. Therefore, association studies of alcoholism or antisocial personality disorder in Chinese may be more reliable if pure antisocial alcoholics, pure antisocial personality disorders, and normal controls as MAO-A gene are examined.

METHODS

In this study, the associations among antisocial alcoholism, antisocial personality disorder, and the uVNTR and EcoRV polymorphisms of the MAO-A gene, both individually and as a haplotype, were investigated among male adults recruited from jails in Taipei. A total of 129 Chinese Han males were studied, including 41 with antisocial personality disorder with alcoholism, 50 with antisocial personality disorder but without alcoholism, and 38 without either disorder as a jail control group. The diagnoses of alcohol dependence and antisocial personality disorder were made according to DSM-IV criteria. In addition, 77 normal controls were collected from the community.

RESULTS

Strong linkage disequilibrium was found for the uVNTR and EcoRV variants of MAO-A gene in each study group.

CONCLUSIONS

No significant association was observed between these two polymorphisms and antisocial personality disorder with alcoholism, either individually or for the haplotype, or for antisocial personality disorder without alcoholism. Thus, neither antisocial alcoholism nor antisocial personality disorder was associated with the genetic variants of MAO-A gene.

Is long-term heavy alcohol consumption toxic for brain serotonergic neurons? Relationship between years of excessive alcohol consumption and serotonergic neurotransmission

The relationship between years of excessive alcohol consumption and central serotonergic neurotransmission, as assessed by the prolactin (PRL) response to D-fenfluramine, was investigated in 22 male alcohol-dependent subjects. A negative correlation was obtained, that is, the longer duration of excessive alcohol consumption the lower PRL response to D-fenfluramine. It is therefore suggested that long duration of excessive alcohol consumption in alcohol-dependent subjects causes a reduction in central serotonergic neurotransmission, possibly by a toxic effect of alcohol on serotonin neurons. The relationship between depressive and anxiety symptoms during on-going drinking and the PRL response to D-fenfluramine was also investigated. No such correlations were obtained, suggesting that reduction in central serotonergic neurotransmission does not pre-dispose to the development of depressive and anxiety symptoms, at least in relation to on-going drinking in alcohol-dependent subjects.

Conduct disorder: a biopsychosocial review

OBJECTIVE

To review published works on the epidemiology, risk factors, protective factors, typologies, and genetic aspects of conduct disorder (CD).

METHOD

Findings from refereed journal articles and current texts in the field are briefly summarized.

RESULTS

CD is commonly encountered in clinical practice. Factors strongly predictive of future delinquency include past offenses, antisocial peers, impoverished social ties, early substance use, male sex, and antisocial parents. Factors that moderately predict recidivism include early aggression, low socioeconomic status (SES), psychological variables such as risk taking and impulsivity, poor parent-child relationships, poor academic performance, early medical insult, and neuropsychological variables such as poor verbal IQ. Mildly predictive variables include other family characteristics such as large family size, family stress, discord, broken home, and abusive parenting, particularly neglect. Protective factors include individual factors such as skill competence (in social and other arenas), adult relationships, prosocial and proeducational values, and strong social programs and supports.

CONCLUSIONS

We know a great deal about psychosocial risk factors for CD. Some research into protective factors and genetic contributions exists but is in its early stages. Future work will increase our knowledge about subtypes, developmental pathways, and CD treatment.

Measurement of aggression in psychiatric patients

This article analyzes, describes, and characterizes the methods used for measuring aggression in studies on psychiatric patients. The authors reviewed all studies published between 1985 and 1994 in seven major psychiatric journals and found 103 studies on adult aggression and 43 on childhood and adolescent aggression. Almost half (44.7%) of the adult studies and 23.3% of the child and adolescent studies did not use any structured instrument; the remainder used a total of 52 different instruments, indicating that the methodology in this area is not well established. The methods used for measuring aggression were mainly of three types: observational measures; self-report questionnaires; and structured chart reviews. Each of these tools is described herein, with special focus on reliability and validity. Overall the reliability of the various scales is high, but the empirical validity is rather poor. In choosing a suitable method for measuring aggression, researchers should take into account the direction of investigation (e.g. state vs. trait aggression, dynamic or biological aspects of aggression) and the target population. Practical suggestions in this regard are offered.

Platelet monoamine oxidase (MAO) activity and alcoholism: is there a genuine association?

Monoamine oxidase (MAO) is a particle-bound flavoenzyme principally located in the outer mitochondrial membrane, which catalyzes the oxidative deamination of a variety of the amine transmitters in the central nervous system. There have been many reports from different groups around the world over the last 20 years that indicated a lower platelet MAO activity was associated with alcoholism. As there are multiple influences upon measured MAO activity, this article attempts to address each of the issues in turn for potential confounding of the reported association. These issues include: the duration of abstinence from alcohol, the substrate used for analysis, gender issues, association with different subtypes of alcoholics, the influence of other psychopathology, personality traits of alcoholics, the question of smoking, and proposed modes of transmission of MAO activity. The initial promise about MAO activity being a possible marker for alcoholism or a least a genetically predisposed subgroup has receded as the number of negative typology-based studies increases. The failure to account for a major confounding variable, e.g. smoking and other minor but possibly vital confounds in almost all these studies leaves the whole hypothesis open to criticism. However, the possible association between personality traits that might predispose to some if not all substances of addiction to low MAO activity may make it possible to reframe the hypothesized association in the setting of a generalized predisposition to addictions in particular, and to psychopathology in general. Nonetheless the association remains of great interest and may yet yield vital genetic and clinical information.

Antisocial tendencies in alcohol-dependent men and their relation to harman, salsolinol and dopamine

Plasma dopamine, β-carbolines (norharman, harman) and isoquinolines ((R)- and (S)-salsolinol) were examined for their relationship to antisocial tendencies in 138 drinking men with an alcohol dependence syndrome according to ICD-10 criteria. Antisociality was assessed according to the following criteria: delinquency, involvement in fist-fights and homelessness. The personality structure was documented by the Tridimensional Personality Questionnaire of Cloninger. An early age of onset of alcohol dependence and a high degree of 'novelty seeking' were associated with antisocial tendencies. Of the β-carbolines and isoquinolines, harman and (S)-salsolinol were significantly decreased among antisocial alcoholics. Norharman, (R)-salsolinol and dopamine were not associated with antisocial personality. The contribution of endogenous alkaloids to the biological characterization of antisocial tendencies in alcoholics is described.

Neurotransmitter and endocrine modulation of aggressive behavior and its components in normal humans

Correlations between aggressiveness and its components and plasma concentrations of norepinephrine (NE), epinephrine (EPI), testosterone (T), cortisol (Cort) and prolactin (Prl) were studied in 158 physically and psychologically healthy male volunteers. Global aggressiveness, examined directly in the probands by the Buss-Durkee Hostility Inventory (BDHI), was not correlated with any of the biochemical parameters investigated, but reports by first-degree relatives and spouses showed positive correlations between global aggressiveness and NE and T levels. The BDHI scores for 'irritability' and 'resentment' were positively correlated with NE, T and Cort.

Psychopathy, platelet MAO activity and criminality among former juvenile delinquents

Psychopathy-related personality traits as well as platelet monoamine oxidase (MAO) activity and criminality from the age of 15 years were studied in a group of 68 male former juvenile delinquents and 32 control subjects. The former juvenile delinquents registered for crime as adults were found to have higher Psychopathy Check List (PCL) scores and lower platelet MAO activity than either juvenile delinquents who were not registered criminals from the age of 15 years or non-criminal controls. Although PCL scores and platelet MAC activity were unrelated, a configural frequency analysis showed a significant interaction. Individuals with PCL scores, low platelet MAO activity and persistent criminal behaviour constituted a significant "type'. Among the 27 former juvenile delinquents who developed persistent criminality, 21 subjects (78%) had PCL scores greater than 0 and low platelet MAO activity, while none of these persistent criminals were characterized by a combination of zero PCL score and high platelet MAO activity.

A dinucleotide repeat polymorphism at the gene for monoamine oxidase A and measures of aggressiveness

The relationship between measures of aggressiveness (personality questionnaire scales, conduct disorder diagnosis, and symptom count) and a recently discovered dinucleotide repeat length polymorphism at the monoamine oxidase type A (MAOA) gene (MAOCA-1) as a candidate locus was examined in adolescents using polymerase chain reaction. No significant correlation between aggression scales and repeat length at the MAOCA-1 marker was found, whereas the categorical diagnosis of conduct disorder showed a nonsignificant trend for an association with the marker. Alternative explanations of this trend are discussed. The data obtained suggest that the polymorphism studied is not associated with the variation in aggressiveness.

Platelet monoamine oxidase activity levels in subgroups of alcoholics: diagnostic, temporal, and clinical correlates

Platelet monoamine oxidase (MAO) activity levels were measured in 47 male inpatient alcoholics to determine whether this biological marker might be useful in differentiating subtypes of alcoholics. Of the subgrouping methods tested, only type 2 alcoholics defined by the criteria of Gilligan et al had significantly lower platelet MAO activity than type 1 alcoholics at intake, but this finding was not stable over time in a subset of subjects. Neither separating male veteran alcoholics into either of two other variations of the type 1/type 2 subtypes, nor classifying the sample into primary alcoholics versus primary ASPD with secondary alcoholism categories, yielded significant differences between subgroups. Generally, enzyme activity levels (Vmax) were higher about 10 days after stopping drinking compared to platelet MAO values determined in thrombocytes obtained after approximately 4 weeks abstinence; these levels remained relatively stable 3 months later in a cohort of subjects. Tobacco smoking was significantly negatively correlated to platelet MAO activity levels.

Longitudinal observations of monoamine oxidase B in alcoholics: differentiation of marker characteristics

The marker characteristics of monoamine oxidase B (MAO B) in human platelets were investigated in a clinical study of 59 alcoholics (diagnosed according to the criteria of ICD-10) observed over a period of 6 months. Demographic and family history were obtained by a structured interview, including the substance abuse section of CIDI (Composite International Diagnostic Interview). The patient's personality was assessed by Cloninger's Tridimensional Personality Questionnaire (TPQ). Blood samples were first drawn during chronic intoxication (day of admission to the hospital for detoxication), after short-term abstinence (8 days later), medium-term (3 months later), and long-term abstinence (6 months later). A group of 22 matched healthy nonalcoholics served as controls studied under sober conditions and during acute intoxication (4 hr after ingestion of 1 g ethanol/kg body weight). All platelet samples were investigated with 6 kynuramine concentrations as substrate (fluorometric assay) in the absence and presence of 200 mM ethanol (ETOH) in vitro. MAO B activity was significantly reduced in alcoholics during chronic intoxication (Vmax: 2.70 +/- 0.15 nmol/mg protein) compared with sober (Vmax: 3.25 +/- 0.23 nmol/min/mg protein) and acutely intoxicated controls that turned to normal during abstinence. However, MAO B activity obtained during medium- and long-term abstinence was significantly lowered in patients with high novelty-seeking and impulsiveness scores in the TPQ, a history of suicide attempts, or an alcoholic mother. The affinity of MAO B (Km values) was unchanged in alcoholics at any time investigated. Addition of ETOH in vitro reduced the affinity.(ABSTRACT TRUNCATED AT 250 WORDS)

Criminality and platelet monoamine oxidase activity in former juvenile delinquents as adults

Platelet monoamine oxidase (MAO) activity was estimated in 70 former delinquent boys and 40 controls now aged 38-46 years. Platelet MAO activity was compared with their early criminal behaviour (before the age of 15) and their late registered criminality from the age of 15). Mean platelet MAO activity in subjects with both early and late criminality was significantly lower than that in former delinquents without late criminality. There was no significant difference in mean platelet MAO activity between controls and delinquents with early but no late criminality. When delinquents with early criminality were divided into a low and a high MAO group, the relative risk to be registered for late criminality was about 3.1 times higher for the subjects in the low MAO group. Thus, individuals with low platelet MAO activity run an increased risk of continued criminal behaviour.