High levels of dopamine D2 receptors in unaffected members of alcoholic families: possible protective factors.
BACKGROUND
Predisposition to alcoholism is likely an interaction between genetic and environmental factors that confer vulnerability and protection. Alcoholic subjects have low levels of dopamine D(2) receptors in striatum, and increasing D(2) receptor levels in laboratory animals reduces alcohol consumption.


OBJECTIVE
To test whether high levels of D(2) receptors may be protective against alcoholism and whether this is mediated by their modulation of activity in orbitofrontal cortex and cingulate gyrus (regions involved in salience attribution, emotional reactivity, and inhibitory control).


METHODS
Research (nonalcoholic subjects with a family history of alcoholism) and comparison (nonalcoholic subjects with a negative family history) sample.


METHODS
Outpatient setting.


METHODS
Fifteen nonalcoholic subjects who had an alcoholic father and at least 2 other first- or second-degree relatives who were alcoholics (family-positive group) and 16 nonalcoholic controls with no family history of alcoholism (family-negative group).


METHODS
Results of positron emission tomography with raclopride C 11 to assess D(2) receptors and with fludeoxyglucose F 18 to assess brain glucose metabolism (marker of brain function). Personality measures were obtained with the Multidimensional Personality Questionnaire.


RESULTS
Availability of D(2) receptors was significantly higher in caudate and ventral striatum in family-positive than family-negative subjects. In family-positive but not family-negative subjects, striatal D(2) receptors were associated with metabolism in anterior cingulate (Brodmann area 24/25) and orbitofrontal (Brodmann area 11) and prefrontal (Brodmann area 9/10) cortices, and with personality scores of positive emotionality.


CONCLUSIONS
The higher-than-normal D(2) receptor availability in nonalcoholic members of alcoholic families supports the hypothesis that high levels of D(2) receptors may protect against alcoholism. The significant associations between D(2) receptors and metabolism in frontal regions involved with emotional reactivity and executive control suggest that high levels of D(2) receptors could protect against alcoholism by regulating circuits involved in inhibiting behavioral responses and in controlling emotions.
Volkow
Nora D
ND
National Institute on Drug Abuse, 6001 Executive Boulevard, Rockville, MD 20857, USA. nvolkow@nida.nih.gov
Wang
Gene-Jack
GJ
Begleiter
Henri
H
Porjesz
Bernice
B
Fowler
Joanna S
JS
Telang
Frank
F
Wong
Christopher
C
Ma
Yeming
Y
Logan
Jean
J
Goldstein
Rita
R
Alexoff
David
D
Thanos
Peter K
PK
D000328:Adult; D000437:Alcoholism / Q000235:genetics* / Q000378:metabolism* / Q000517:prevention & control; D000553:Ambulatory Care; D001479:Basal Ganglia / Q000000981:diagnostic imaging / Q000378:metabolism; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D002421:Caudate Nucleus / Q000000981:diagnostic imaging / Q000378:metabolism; D004644:Emotions / Q000502:physiology; D005190:Family; D005260:Female; D019788:Fluorodeoxyglucose F18; D005625:Frontal Lobe / Q000000981:diagnostic imaging / Q000378:metabolism; D020022:Genetic Predisposition to Disease; D005947:Glucose / Q000378:metabolism; D006179:Gyrus Cinguli / Q000000981:diagnostic imaging / Q000378:metabolism; D006801:Humans; D008297:Male; D010551:Personality / Q000145:classification; D010552:Personality Assessment; D049268:Positron-Emission Tomography; D020891:Raclopride; D017448:Receptors, Dopamine D2 / Q000235:genetics* / Q000378:metabolism*
D017448:Receptors, Dopamine D2; D019788:Fluorodeoxyglucose F18; D020891:Raclopride; D005947:Glucose