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[January 8, 2007]
Reduced Frontal-Lobe Activity and Impulsivity May Be Linked to Alcoholism Risk
 
A new study of brain processes provides support for the theory that increased impulsivity, or a lack of impulse control, is involved in a predisposition to developing many psychiatric disorders, including alcohol dependence. Results of the study – conducted by researchers at SUNY Downstate Medical Center in Brooklyn – are published in the January issue of Alcoholism: Clinical & Experimental Research (ACER).
“Altered impulsivity is a prominent manifestation in many disinhibitory psychiatric disorders, such as alcohol- or substance-related disorders, conduct disorder, attention-deficit hyperactive disorder (ADHD), antisocial personality disorder (ASP), bipolar disorder, impulse control disorders, and so on,” said Bernice Porjesz, Professor of Psychiatry & Behavioral Sciences, and Director of the Henri Begleiter Neurodynamics Laboratory at SUNY Downstate Medical Center.  
“Individuals suffering with these disorders may frequently and unpredictably act without planning in advance or without regard to the negative consequences of their behaviors, which in turn can result in serious aftermath.  In severe cases, it may lead to danger to the patient or to others.”
Porjesz added that the majority of psychiatric diseases are “complex diseases,” meaning that their development is influenced by an underlying biological susceptibility of genetic factors, environmental factors, and interactions among multiple genes and the environment.
“Disinhibitory disorders share many similar clinical presentations as well as similar neurobiological abnormalities such as brain waves,” said Porjesz.  “This suggests that this group of disorders may have some underlying genetic vulnerabilities in common that contribute to the disorders.  One recent study of genetic and environmental contributions to internalizing and externalizing disorders determined that the single most important factor underlying externalizing disorders is a genetic liability involving impulse control.”
Results of the study showed that alcohol-dependent subjects, as well as those individuals with high impulsivity, had significantly lower P3 amplitudes (an evoked response of the brain reflecting the level of neural inhibition in the central nervous system - the larger the P3, the more the inhibition) and reduced frontal-lobe activity while processing visual target signals.
“This is the first study to demonstrate that reduced brain activity in the frontal lobe during processing of target visual stimuli is highly related to impulsivity, regardless of a clinical diagnosis such as alcoholism,” said Porjesz.  “Genetically influenced underlying factors, such as neural disinhibition and impulsivity, involve frontal-lobe function and influence a wide range of clinical outcomes.  Thus, the low P3 amplitude and reduced frontal activation that we found reflect risk for the development of many externalizing disorders, not just specifically alcohol dependence.”
As part of a large nine-center collaborative study known as COGA (Collaborative Study on the Genetics of Alcoholism), Dr. Porjesz and colleagues are also trying to identify genes associated with impulsivity, and the underlying predisposition involved in disinhibitory disorders, by following young offspring of alcoholics with “risk genes” as they go though the age of risk and respond to their environmental factors.
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Alcoholism: Clinical & Experimental Research (ACER) is the official journal of the Research Society on Alcoholism and the International Society for Biomedical Research on Alcoholism.  Co-authors of the ACER paper, “Reduced Frontal Lobe Activity in Subjects with High Impulsivity and Alcoholism,” were: Andrew C. H. Chen, Madhavi Rangaswamy, Chella Kamarajan, Yongqiang Tang, Kevin A. Jones, David B. Chorlian, Arthur T. Stimus, and Henri Begleiter of the Neurodynamics Laboratory in the Department of Psychiatry at SUNY Downstate Medical Center in Brooklyn.  The study was funded by the National Institute on Alcohol Abuse and Alcoholism.
Journalists: A full copy of the manuscript may be obtained by contacting Mary Newcomb at the ACER Editorial Office: 317.375.0819 or mnewcomb-acer@earthlink.net.  The project is supported by the Addiction Technology Transfer Center Network.