SPECT imaging of nicotinic acetylcholine receptors in nonsmoking heavy alcohol drinking individuals

Abstract

Background: The high rate of comorbidity of tobacco smoking with alcohol drinking suggests common neural substrates mediate the two addictive disorders. The beta(2)*-containing nicotinic acetylcholine receptor (beta(2)*-nAChR) has recently emerged as a prime candidate because some alpha and beta subunit genes have been linked to alcohol consumption and alcohol use behaviors. We hypothesized that beta(2)*-nAChR availability would be altered by alcohol in heavy drinking nonsmokers.

Methods: Eleven heavy drinking (mean age 39.6+/-12.1 years) and 11 age and sex-matched control (mean age 40.8+/-14.1 years) nonsmokers were imaged using [(123)I]5-IA-85380 ([(123)I]5-IA) single photon emission computed tomography (SPECT). Heavy alcohol drinkers drank varied amounts of alcohol (70-428/month) to facilitate exploratory linear analyses of the possible effects of alcohol.

Results: Heavy drinkers consumed on average 9.1+/-7.3 drinks/occasion; whereas controls drank 1.2+/-0.9 drinks/occasion. Heavy drinkers were imaged 2.0+/-1.6 days after last alcoholic beverage. Overall, there were no significant differences in beta(2)*-nAChR availability between the heavy drinking and control nonsmokers. Exploratory analyses of other factors that may be uniquely regulated by alcohol suggested no effects of age, number of alcohol drinks, years drinking, severity of drinking, craving or withdrawal.

Conclusions: These preliminary analyses do not suggest a decrease in receptor availability in heavy drinking nonsmokers as compared to control nonsmokers. However, a larger study is warranted to explore effects of heavy alcohol drinking on other variables, such as sex, smoking, and genetic make up.

Figure 1

Scatterplots illustrating individual [¹²³I] 5-IA regional distribution volume (regional activity/free plasma parent) determined from the region of interest analyses for each individual subject is illustrated for the thalamus, striatum, and mean cortex (average of parietal, frontal, anterior cingulate, temporal and occipital cortices). Drinkers were imaged on average 2d after last drink. There were no significant differences between the total control and heavy drinking nonsmokers.