Serotonin in alcoholic violent offenders

Huntington's disease: a forensic risk factor in women

Background

Huntington's disease (HD) is an autosomal dominant, neurodegenerative disorder. Associated cognitive deficits including impulsivity and disinhibition are the same factors that also predispose to forensic risk. Men tend to be perpetrators of more severe violent behaviours than women and women are less likely than men to be arrested for violence. This finding is not applicable in the case of women with Huntington's disease and explored in the three clinical cases of women with HD and their forensic histories that are subsequently described.

Case presentation

'A' was admitted from court following a charge of arson and reckless behavior, with increasing severity and frequency of self-harm and attempted suicide. This case demonstrates someone who had previously presented to psychiatric services on multiple occasions for various reasons, culminating in a serious criminal charge of arson due to psychiatric symptoms associated with HD.'B' was arrested and imprisoned after having been charged with actual bodily harm (ABH) for assaulting her partner and young daughter then breaking her bail conditions. Although she was gene positive for HD she had no neurological symptoms of the disease. B was given leave but needed to be recalled to hospital by police. Six weeks later the medical recommendation for a court imposed hospital order was overturned as B presented and articulated her case so convincingly in court. This case demonstrates that even in the absence of psychiatric history or movement disorder there may be substantial forensic risk indicated by subtle underlying cognitive deficits due to changes in executive function affecting the frontal lobes.'C' was admitted to acute psychiatric services after being found wandering in traffic wanting to die. She had been diagnosed with HD in the previous year and had a long criminal record on a background of alcohol dependency. Following transfer to a specialist psychiatric unit, she engaged well with a neurobehavioural levels system which rewards desirable and appropriate behaviours and she responded well to a highly structured environment resulting in discharge to a community placement.

Conclusions

These three case studies aim to highlight the need to raise awareness of the increased forensic risk in women with HD. Although criminal behaviour is less frequently observed in women than men and usually violence is less severe in women, HD may cause or contribute to criminal behaviour that can be violent in nature in women who are gene carriers for HD even in the absence of movement disorder, psychiatric symptoms or overt cognitive deficits. Assessment and earlier treatment in appropriate hospital settings may successfully contain and modify behaviours leading to reduced levels of risk and recidivism in this vulnerable patient group.

Adolescent intermittent ethanol reduces serotonin expression in the adult raphe nucleus and upregulates innate immune expression that is prevented by exercise

Serotonergic neurons of the raphe nucleus regulate sleep, mood, endocrine function, and other processes that mature during adolescence. Alcohol abuse and binge drinking are common during human adolescence. We tested the novel hypothesis that adolescent intermittent ethanol exposure would alter the serotonergic system that would persist into adulthood. Using a Wistar rat model of adolescent intermittent ethanol (AIE; 5.0g/kg, i.g., 2-day on/2-day off from postnatal day [P]25 to P55), we found a loss of dorsal raphe nucleus (DRN) serotonin (5-HT)-immunoreactive (+IR) neurons that persisted from late adolescence (P56) into adulthood (P220). Hypothalamic and amygdalar DRN serotonergic projections were reduced following AIE. Tryptophan hydroxylase 2, the rate-limiting 5-HT synthesizing enzyme, and vesicular monoamine transporter 2, which packages 5-HT into synaptic vesicles, were also reduced in the young adult midbrain following AIE treatment. Adolescent intermittent ethanol treatment increased expression of phosphorylated (activated) NF-κB p65 as well as markers of microglial activation (i.e., Iba-1 and CD11b) in the adult DRN. Administration of lipopolysaccharide to mimic AIE-induced innate immune activation reduced 5-HT+IR and increased phosphorylated NF-κB p65+IR similar to AIE treatment. Voluntary exercise during adolescence through young adulthood blunted microglial marker and phosphorylated NF-κB p65+IR, and prevented the AIE-induced loss of 5-HT+IR neurons in the DRN. Together, these novel data reveal that AIE reduces 5-HT+IR neurons in the adult DRN, possibly through an innate immune mechanism, which might impact adult cognition, arousal, or reward sensitivity. Further, exercise prevents the deleterious effects of AIE on the serotonergic system.

Description and validation of a dynamical systems model of presynaptic serotonin function: genetic variation, brain activation and impulsivity

Despite more than a decade of empirical work on the role of genetic polymorphisms in the serotonin system on behavior, the details across levels of analysis are not well understood. We describe a mathematical model of the genetic control of presynaptic serotonergic function that is based on control theory, implemented using systems of differential equations, and focused on better characterizing pathways from genes to behavior. We present the results of model validation tests that include the comparison of simulation outcomes with empirical data on genetic effects on brain response to affective stimuli and on impulsivity. Patterns of simulated neural firing were consistent with recent findings of additive effects of serotonin transporter and tryptophan hydroxylase-2 polymorphisms on brain activation. In addition, simulated levels of cerebral spinal fluid 5-hydroxyindoleacetic acid (CSF 5-HIAA) were negatively correlated with Barratt Impulsiveness Scale (Version 11) Total scores in college students (r = -.22, p = .002, N = 187), which is consistent with the well-established negative correlation between CSF 5-HIAA and impulsivity. The results of the validation tests suggest that the model captures important aspects of the genetic control of presynaptic serotonergic function and behavior via brain activation. The proposed model can be: (1) extended to include other system components, neurotransmitter systems, behaviors and environmental influences; (2) used to generate testable hypotheses.

HTR3B is associated with alcoholism with antisocial behavior and alpha EEG power--an intermediate phenotype for alcoholism and co-morbid behaviors

Alcohol use disorders (AUD) with co-morbid antisocial personality disorder (ASPD) have been associated with serotonin (5-HT) dysfunction. 5-HT3 receptors are potentiated by ethanol and appear to modulate reward. 5-HT3 receptor antagonists may be useful in the treatment of early-onset alcoholics with co-morbid ASPD. Low-voltage alpha electroencephalogram (EEG) power, a highly heritable trait, has been associated with both AUD and ASPD. A recent whole genome linkage scan in one of our samples, Plains American Indians (PI), has shown a suggestive linkage peak for alpha power at the 5-HT3R locus. We tested whether genetic variation within the HTR3A and HTR3B genes influences vulnerability to AUD with comorbid ASPD (AUD+ASPD) and moderates alpha power. Our study included three samples: 284 criminal alcoholic Finnish Caucasians and 234 controls; two independent community-ascertained samples with resting EEG recordings: a predominantly Caucasian sample of 191 individuals (Bethesda) and 306 PI. In the Finns, an intronic HTR3B SNP rs3782025 was associated with AUD+ASPD (P=.004). In the Bethesda sample, the same allele predicted lower alpha power (P=7.37e(-5)). Associations between alpha power and two other HTR3B SNPs were also observed among PI (P=.03). One haplotype in the haplotype block at the 3' region of the gene that included rs3782025 was associated with AUD+ASPD in the Finns (P=.02) and with reduced alpha power in the Bethesda population (P=.00009). Another haplotype in this block was associated with alpha power among PI (P=.03). No associations were found for HTR3A. Genetic variation within HTR3B may influence vulnerability to develop AUD with comorbid ASPD. 5-HT3R might contribute to the imbalance between excitation and inhibition that characterize the brain of alcoholics.

The next challenge for psychiatric genetics: characterizing the risk associated with identified genes

BACKGROUND

As advances in genetics further our ability to identify genes influencing psychiatric disorders, the next challenge facing psychiatric genetics is to characterize the risk associated with specific genetic variants in order to better understand how these susceptibility genes are involved in the pathways leading to illness.

METHODS

To further this goal, findings from behavior genetic analyses about how genetic influences act can be used to guide hypothesis testing about the effects associated with specific genes.

RESULTS

Using the phenotype of alcohol dependence as an example, this paper provides an overview of how the integration of behavioral and statistical genetics can advance our knowledge about the genetics of psychiatric disorders. Areas currently being investigated in behavior genetics include careful delineation of phenotypes, to examine the heritability of various aspects of normal and abnormal behavior; developmental changes in the nature and magnitude of genetic and environmental effects; the extent to which different behaviors are influenced by common genes; and different forms of gene-environment correlation and interaction.

CONCLUSIONS

Understanding how specific genes are involved in these processes has the potential to significantly enhance our understanding of the development of psychiatric disorders.

Antisoziales Verhalten im Jugendalter: Entstehungsbedingungen und Verlaufsformen

Zusammenfassung: Ausmaß und Verbreitung von Gewalt und Delinquenz unter Kindern und Jugendlichen haben in den letzten 15 Jahren kontinuierlich zugenommen. Bei dem Bestreben, dieser Entwicklung entgegenzuwirken, können neuere Erkenntnisse der entwicklungspsychopathologischen und neurobiologischen Forschung wichtige Hilfestellung leisten. In einem Modell von Moffitt werden zwei Entwicklungswege antisozialer Verhaltensprobleme beschrieben, die sich hinsichtlich des Störungsbeginns und -verlaufs unterscheiden: ein Pfad, der durch eine frühzeitig einsetzende und über den Lebenslauf stabile Symptomatik charakterisiert ist (“life-course persistent”), sowie ein Pfad mit einem episodenhaften, auf das Jugendalter begrenzten Auftreten antisozialer Auffälligkeiten (“adolescence-limited”). Während im letzteren Fall die spezifischen Entwicklungsaufgaben und Lebensbedingungen Jugendlicher eine maßgebliche Rolle bei Entstehung und Verlauf spielen, entsteht persistentes antisoziales Verhalten als Resultat eines transaktionalen Prozesses zwischen Kind und Umwelt. Neben psychosozialen Faktoren kommt dabei biologischen Prädispositionen (genetische Belastung) und psychologischen Dispositionen (Temperaments- und Persönlichkeitsmerkmale) eine zentrale Bedeutung zu. Wichtige Aufschlüsse über die zugrunde liegenden Mechanismen versprechen die jüngsten Fortschritte der neurobiologischen und persönlichkeitspsychologischen Forschung. Die Integration beider Ansätze kann dazu beitragen, Maßnahmen der Prävention und Frühintervention zielgruppenorientierter auszurichten und damit wirkungsvoller zu gestalten.