A non-additive interaction of a functional MAO-A VNTR and testosterone predicts antisocial behavior

A functional VNTR polymorphism in the promoter of the monoamine oxidase A gene (MAOA-LPR) has previously been shown to be an important predictor of antisocial behavior in men. Testosterone analogues are known to interact with the MAOA promoter in vitro to influence gene transcription as well as in vivo to influence CSF levels of the MAO metabolite 3-methoxy-4-hydroxyphenylglycol (MHPG) in human males. We examined the possible joint effects of testosterone (measured in CSF) and MAOA-LPR genotype on antisocial personality disorder and scores on the Brown-Goodwin Aggression scale in 95 unrelated male criminal alcoholics and 45 controls. The results confirm that MAOA genotype and CSF testosterone interact to predict antisocial behaviors. The MAOA/testosterone interaction also predicted low levels of CSF MHPG, which tentatively suggests the possibility that the interaction may be mediated by a direct effect on gene transcription. If replicated these findings offer plausible explanations for previous inconsistencies in studies of the relationship between testosterone and male human aggression, as well as for how MAOA genotype may influence aggressive behavior in human males.

CSF studies in violent offenders. I. 5-HIAA as a negative and HVA as a positive predictor of psychopathy

Low serotonin activity in man has been related to impulsive, self-destructive violence but not to instrumental aggression aimed at dominance. A relationship has also been suggested between aggression and high catecholaminergic activity. Several studies have reported signs of aberrant dopaminergic function in attention deficit hyperactivity disorder, autism, and schizophrenia. In 22 violent offenders undergoing pretrial forensic psychiatric investigation, interpersonal and behavioral features of psychopathy, measured by the Psychopathy Checklist Revised (PCL-R), were significantly predicted by low cerebrospinal fluid (CSF) concentrations of 5-HIAA and high CSF concentrations of HVA in multivariate regression models. CSF concentrations of MHPG did not contribute to the model. This seems to link the outward-directed aggression of psychopathy to serotonergic hypofunctioning and high dopamine turnover, which might account for disinhibition of destructive impulses.

Family psychiatric history, cerebrospinal fluid monoamine metabolites, and temperament in infants

BACKGROUND

Variations in cerebrospinal fluid (CSF) levels of the monoamine metabolites 5-hydroxyindoleacetic acid, 3-methoxy-4-hydroxyphenylglycol, and homovanillic acid have been associated with behavioral abnormalities in nonhuman primates, and with psychopathology in studies of children and adults.

METHODS

We assayed monoamine metabolites in "left-over" spinal fluid from 167 neurologically normal newborn infants (0-3 months of age), and later (at age 18-21 months of age) obtained their family psychiatric histories and assessed their temperament using the Colorado Childhood Temperament Inventory (CCTI).

RESULTS

Family history of antisocial personality disorder predicted significantly lower scores for soothability (p = .003) at 18-21 months. There were no statistically significant associations between newborn monoamine metabolite levels and any aspect of temperament on the CCTI.

CONCLUSIONS

These findings suggest complex relationships between genetic liability for psychiatric disorders and CSF monoamine metabolite levels; those relationships do not seem to be mediated by infant temperament. It appears likely that interindividual differences in monoamine metabolite levels change over the course of development in humans.

CSF biochemistries, glucose metabolism, and diurnal activity rhythms in alcoholic, violent offenders, fire setters, and healthy volunteers

BACKGROUND

There is an extensive literature describing a central serotonin deficit in alcoholic, impulsive, violent offenders and fire setters. In the present study, we investigated biochemical concomitants of impulsivity and aggressiveness, and the physiological consequences of reduced central serotonin turnover.

METHODS

Forty-three impulsive and 15 nonimpulsive alcoholic offenders and 21 healthy volunteers were studied in the forensic psychiatry ward of a university psychiatric department. The subjects underwent lumbar punctures and oral glucose and aspartame challenges, and their diurnal activity rhythm was measured with physical activity monitors. Discriminant function analyses were used to investigate psychophysiological and biochemical concomitants of aggressive and impulsive behaviors.

RESULTS

Alcoholic, impulsive offenders with antisocial personality disorder had low mean cerebrospinal fluid (CSF) 5-hydroxyindoleacetic acid (5-HIAA) and corticotropin levels and high mean CSF testosterone concentrations. Compared with healthy volunteers, they showed increased physical activity during the daytime. Alcoholic, impulsive offenders with intermittent explosive disorder had a low mean CSF 5-HIAA concentration and blood glucose nadir after an oral glucose challenge, and desynchronized diurnal activity rhythm. Healthy volunteers had mean CSF 5-HIAA concentrations that were intermediate between those of alcoholic, impulsive and nonimpulsive offenders. Alcoholic, nonimpulsive offenders had a significantly higher mean CSF 5-HIAA concentration than all the other groups, including healthy volunteers.

CONCLUSIONS

In the present sample, a low CSF 5-HIAA concentration was primarily associated with impulsivity and high CSF testosterone concentration, with aggressiveness or interpersonal violence.

Suicidality and 5-hydroxyindoleacetic acid concentration associated with a tryptophan hydroxylase polymorphism

BACKGROUND

To examine whether the tryptophan hydroxylase (TPH) gene, which codes for the rate-limiting enzyme in the biosynthesis of serotonin, may be a factor influencing serotonin turnover and behaviors controlled by serotonin.

METHODS

Using a polymerase chain reaction-based method, TPH genotype was determined in DNA samples from 56 impulsive and 14 nonimpulsive, alcoholic, violent offenders and 20 healthy volunteers.

RESULTS

In the behaviorally extreme impulsive group, we observed a significant association between TPH genotype and cerebrospinal fluid 5-hydroxyindoleacetic acid (5-HIAA) concentration. No association of TPH genotype with impulsive behavior was detected. The polymorphism was also associated with a history of suicide attempts in all violent offenders, independent of impulsivity status and cerebrospinal fluid 5-HIAA concentration.

CONCLUSION

In some individuals, a genetic variant of the TPH gene may influence 5-HIAA concentration in the cerebrospinal fluid and predisposition to suicidal behavior.

CSF studies on alcoholism and related behaviours

1. A defect in central serotonin metabolism may manifest itself in poor impulse control leading to attempts at suicide, violence towards others, and Type II alcohol abuse. 2. Studies reporting negative associations between low CSF levels of the serotonin metabolite 5-HIAA and personality traits of aggressiveness and hostility are reviewed. 3. We also studied pathological gamblers. They showed significantly increased central noradrenaline metabolism, perhaps related to sensation seeking.

Low cerebrospinal fluid 5-hydroxyindoleacetic acid concentration differentiates impulsive from nonimpulsive violent behavior

Relationships of impulsive and nonimpulsive violent behavior to cerebrospinal fluid (CSF) monoamines and their metabolic concentrations were studied in thirty-six violent offenders. A relatively low 5-hydroxyindoleacetic acid (5HIAA) concentration was found in the CSF of impulsive violent offenders. This was not true for the offenders who had premeditated their acts. Other CSF monoamine or metabolite concentrations were not significantly different between the two groups. Of the groups studied, impulsive violent offenders who had attempted suicide had the lowest 5HIAA levels. A low CSF 5HIAA concentration may be a marker of impulsivity rather than violence.

Aggression, suicide, and serotonin: relationships to CSF amine metabolites

In an earlier, separate study, the authors found that human aggression and suicide (a specific aggression-related behavior) were associated with lower levels of CSF 5-hydroxyindoleacetic acid (5-HIAA), a serotonin metabolite. That study focused on subjects with personality disorders without affective illness. In the present study they examine the life history of aggression and history of suicidal behavior in 12 subjects with borderline personality disorders without major affective disorder. Histories of aggressive behaviors and of suicide attempts were significantly associated with each other, and each was significantly associated with lower 5-HIAA levels. Altered serotonin metabolism may be a highly significant contributing factor to these behaviors in whatever diagnostic group they occur.

Adenylate kinase activity in cerebrospinal fluid of schizophrenic and certain other psychiatric symptomatologies

Adenylate kinase activity in the cerebrospinal fluid (CSF) was investigated in 29 patients with psychiatric symptomatologies. Such activity was demonstrated in 18 of the 19 individuals with schizophrenic or other psychotic or borderline psychotic symptomatology. No activity was seen in the remaining 10 patients with non-psychotic nervous and/or functional somatic complaints, nor in the 20 persons whose CSF was examined in connection with spinal anaesthesia, nor in four who were treated with neuroleptic drugs on nonpsychiatric indications. The findings are compatible with the assumption that in persons with psychotic or borderline psychotic symptomatology a lowered membrane electrochemical potential may be associated with some of the symptoms exhibited.