Intermanual differences on motor and psychomotor tests in alcoholics: no evidence for selective right-hemisphere dysfunction

Adolescent Social Isolation as a Model of Heightened Vulnerability to Comorbid Alcoholism and Anxiety Disorders

Individuals diagnosed with anxiety-related illnesses are at increased risk of developing alcoholism, exhibit a telescoped progression of this disease and fare worse in recovery, relative to alcoholics that do not suffer from a comorbid anxiety disorder. Similarly, preclinical evidence supports the notion that stress and anxiety represent major risk factors for the development of alcohol use disorder (AUD). Despite the importance of understanding the link between anxiety and alcoholism, much remains unknown about the neurobiological substrates underlying this relationship. One stumbling block has been the lack of animal models that reliably reproduce the spectrum of behaviors associated with increased vulnerability to these diseases. Here, we review the literature that has examined the behavioral and neurobiological outcomes of a simple rodent adolescent social isolation procedure and discuss its validity as a model of vulnerability to comorbid anxiety disorders and alcoholism. Recent studies have provided strong evidence that adolescent social isolation of male rats leads to the expression of a variety of behaviors linked with increased vulnerability to anxiety and/or AUD, including deficits in sensory gating and fear extinction, and increases in anxiety measures and ethanol drinking. Neurobiological studies are beginning to identify mesolimbic adaptations that may contribute to the behavioral phenotype engendered by this model. Some of these changes include increased excitability of ventral tegmental area dopamine neurons and pyramidal cells in the basolateral amygdala and significant alterations in baseline and stimulated catecholamine signaling. A growing body of evidence suggests that adolescent social isolation may represent a reliable rodent model of heightened vulnerability to anxiety disorders and alcoholism in male rats. These studies provide initial support for the face, construct, and predictive validity of this model and highlight its utility in identifying neurobiological adaptations associated with increased risk of developing these disorders.

Neurocognitive impairments in MDMA and other drug users: MDMA alone may not be a cognitive risk factor

BACKGROUND

MDMA (3,4-methylenedioxymethamphetamine; "Ecstasy") is an amphetamine derivative with mild hallucinogenic and stimulant qualities. MDMA leads to serotonin (5-hydroxytryptamine; 5-HT) neurotoxicity and has been linked to cognitive impairments. It remains unclear whether these impairments are due to MDMA versus other drug use.

METHOD

Neurocognitive functioning was measured in a sample of abstinent polydrug users (n = 52) with a range of MDMA use and healthy nondrug controls (n = 29). Participants completed a comprehensive neuropsychological battery and self-report measures of drug use.

RESULTS

Polydrug users performed worse than controls on spatial span and spatial working memory (ps < .05). Among polydrug users, lifetime marijuana use significantly predicted verbal learning and memory performance (p < .01), while MDMA use was not predictive of cognitive impairment.

CONCLUSIONS

This study and our previous report (Hanson, Luciana, & Sullwold, 2008) suggest that moderate MDMA use does not lead to persistent impairments above and beyond that associated with generally heavy drug use, but polydrug use may lead to dose-related temporal and frontoparietal dysfunction. Marijuana use may be particularly problematic. Cause-effect relations are unclear.

Remission and resurgence of anxiety-like behavior across protracted withdrawal stages in ethanol-dependent rats

BACKGROUND

Alcohol dependence is a chronic disorder in which withdrawal symptoms often persist after detoxification. The purpose of the present experiment was to characterize susceptibility to stress and anxiogenic stimuli in rats over an extended time period following ethanol withdrawal.

METHODS

Male Wistar rats were made dependent via ethanol vapor exposure. The rats were then tested in the elevated plus-maze during acute ethanol withdrawal (ACW, approximately 8 hour), early "protracted" withdrawal (EPW, 2 weeks), or late "protracted" withdrawal (LPW, 6, 12 weeks) following brief restraint or no stress. Principal components analysis was used to identify constructs underlying plus-maze behavior.

RESULTS

Three factors characterized plus-maze performance: anxiety, locomotor activity, and risk assessment/decision making. Spontaneous anxiety-like behavior was increased during ACW, decreased to levels of ethanol-naïve controls during EPW, but markedly resurged during LPW. Withdrawal did not alter sensitivity to the anxiety-like effects of restraint stress. All ethanol-dependent rats showed locomotor hypoactivity that, in contrast to anxiety, remained stable throughout all withdrawal stages. Neither ethanol withdrawal nor restraint stress altered mean "risk assessment/decision making" scores, though ethanol withdrawal altered the emission of "risk assessment/decision making" behavior in relation to anxiety-like behavior and behavioral activation state.

CONCLUSIONS

The findings illustrate and model the spontaneous, severe, and long-lasting nature of behavioral abnormalities that accompany withdrawal from chronic, intermittent ethanol intoxication. The dynamic remission and resurgence in symptoms of negative affect (i.e., behavioral signs of anxiety) during "protracted" withdrawal may complicate recovery from alcoholism.