Intermittent explosive disorder (IED) is a disorder of impulsive aggression that affects as many as 7.3% of the U.S. population during some period of life. Since central serotonergic (5-HT) system dysfunction is related to impulsive aggressive behavior, pharmacologic enhancement of 5-HT activity should reduce impulsive aggressive behavior in individuals with IED.
A double-blind, randomized, placebo-controlled trial of the selective 5-HT uptake inhibitor fluoxetine was conducted in 100 individuals with IED (research diagnostic criteria) and current histories of impulsive aggressive behavior. The primary efficacy measure was the aggression score from the Overt Aggression Scale-Modified (OAS-M) for Outpatient Use. Secondary efficacy measures included the irritability score from the OAS-M and the Clinical Global Impressions-Improvement scale (CGI-I) score. The study took place between July 1990 and July 1999.
Fluoxetine treatment resulted in a sustained reduction in OAS-M aggression, and OAS-M irritability scores, apparent as early as week 2 (p < .01 for aggression and p < .001 for irritability at endpoint). Fluoxetine was also superior to placebo in the proportion of responders on the CGI-I (p < .001). Closer examination of the data revealed that full or partial remission of impulsive aggressive behaviors, as reflected by the A criteria for IED, occurred in 46% of fluoxetine-treated subjects. Fluoxetine did not exert an antidepressant or antianxiety effect, and its effects on impulsive aggression were not influenced by presence of current symptoms of depression or anxiety.
Fluoxetine treatment has a clear antiaggressive effect in impulsive aggressive individuals with IED. However, while fluoxetine's antiaggressive effects appear robust, they lead to full or partial remission of IED in less than 50% of subjects treated with fluoxetine.
"However, only, experimental studies examining aggressive responding in the laboratory, with and without pretreatment with antiinflammatory agents, can shed light on whether IL-1β or other inflammatory cytokines are related to aggressive behavior in any meaningful causal fashion. Given that a disorder of aggression, intermittent explosive disorder displays, a 2% to 3% 1-year prevalence rate in the US (Kessler et al., 2006), and that currently available psychotropic treatments bring <50% of those treated into remission (Coccaro et a., 2009), additional strategies for the examination and intervention of aggression in human subjects is needed. "
"Furthermore, S allele carriers for the 5-HTT promoter region polymorphism (5-HTTPLR) tend to be more aggressive (Aluja et al., 2009; Payer et al., 2012) and have lower 5-HTT availability in 5-HTT rich brain regions (Willeit and Praschak-Rieder, 2010). Serotonin-specific reuptake inhibitors (SSRIs) are effective for reduction of impulsive aggression (Coccaro et al., 2009), and this effect depends on genotype of the 5-HTT (L/L homozygotes respond better than S allele carriers) (Silva et al., 2010), highlighting the importance of individual differences. Despite burgeoning evidence on the importance of the 5-HTT in impulsive aggression, few studies have investigated its in vivo distribution in the brains of patients with IED-IR. "
[Show abstract][Hide abstract] ABSTRACT: Serotonin (5-HT) has consistently been implicated in the pathophysiology of impulsive aggression. In the current study, we tested the hypothesis that 5-HT transporter (5-HTT) binding is reduced in the anterior cingulate cortex (ACC) in impulsive aggressive patients. Additionally, we characterized pathological personality dimensions, with a specific focus on callousness (i.e. emotional indifference, a facet of psychopathy). Callousness is putatively positively correlated with presynaptic 5-HT, and thus could potentially confound the hypothesized negative relation between 5-HTT levels and trait aggression. We determined 5-HTT binding with positron emission tomography and [(11)C]DASB in 29 patients with intermittent explosive disorder (IED-IR) and 30 controls. We assessed group differences in 5-HTT binding in the pregenual ACC, amygdala and subcortical regions and examined correlations between 5-HTT binding and clinical measures. There were no significant differences in 5-HTT binding between IED-IR patients and controls. Trait callousness exhibited a significant, positive correlation with ACC 5-HTT availability. Among IED-IR patients, a trend-level negative partial correlation was observed between trait aggression and ACC 5-HTT availability, while covarying for callousness and age. Exploratory analyses revealed a significant negative correlation between state aggression levels and 5-HTT availability in subcortical regions, namely striatum and thalamus. We did not confirm our hypothesis of lower ACC 5-HTT availability in impulsive aggressive patients, however, the positive correlation between callousness and ACC 5-HTT availability likely played a confounding role. Subtypes of aggression (e.g., reactive vs. proactive aggression), which are differentially associated with pathological personality dimensions such as callousness, may contribute to variability between 5-HT functioning and aggression.
Journal of Psychiatric Research 08/2014; 58. DOI:10.1016/j.jpsychires.2014.07.025 · 3.96 Impact Factor
"For that analysis, we used appropriately adjusted CSF 5-HIAA and PRL[Fen] variables (i.e. CSF 5-HIAA concentration adjusted for CSF HVA concentration ; see Coccaro & Lee, 2010 ; PRL[Fen] adjusted for several covariates and composite aggression scores (see Coccaro et al. 2009). In doing so, we found an inverse correlation between the CSF 5-HIAA and PRL[Fen] variables (r=x0.20) "
[Show abstract][Hide abstract] ABSTRACT: Centrally acting monoamines have long been thought to be associated with component traits of behavior and emotion and are potential biological mediators of psychopathology. In this study we tested the hypothesis that centrally acting monoamines would be associated with measures of affective instability (i.e. affective intensity and affective lability) in healthy and personality disordered human subjects. In total, 57 adult subjects including 19 psychiatrically healthy volunteers and 38 personality disordered individuals were assessed for affective instability with the affective intensity measure (AIM) and the Affective Lability Scale (ALS). Samples of cerebrospinal fluid (CSF) were collected for assay of 5-hydroxyindoleacitic acid (5-HIAA), homovanillic acid (HVA) and 3-methoxy-4-hydroxy-phenylglycol (MHPG). CSF 5-HIAA concentration correlated directly with overall AIM score and, specifically, with the AIM Negative Intensity score, in all subjects and in personality disordered subjects. This result was not affected but the addition of aggression scores or life history of mood disorder to the model. Neither CSF HVA nor MHPG were found to uniquely correlate with either AIM or ALS measure. Higher Affective Intensity scores, Negative Intensity scores, specifically, are directly correlated with higher basal levels of CSF 5-HIAA. This relationship was independent of aggression, life history of mood disorder and general personality traits.
The International Journal of Neuropsychopharmacology 04/2012; 16(2):1-9. DOI:10.1017/S1461145712000211 · 4.01 Impact Factor
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