Brain volumes and neuropsychological performance are related to current smoking and alcoholism history

Riya B Luhar,^1,2 Kayle S Sawyer,^1,2 Zoe Gravitz,^1,2 Susan Mosher Ruiz,^1,2 Marlene Oscar-Berman<sup>1–3

1</sup>US Department of Veterans Affairs, Boston Healthcare System, ²Boston University School of Medicine, ³Athinoula A Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, USA

Background: Dual dependence on alcohol and nicotine is common, with many reports suggesting that more than 80% of alcoholics also smoke cigarettes. Even after cessation of alcohol consumption, many recovering alcoholics continue to smoke. In this exploratory study, we examined how current smoking and a history of alcoholism interacted in relation to brain volumes and neuropsychological performance.
Methods: Participants were 14 abstinent long-term alcoholics (seven current smokers and seven nonsmokers), and 13 nonalcoholics (six current smokers and seven nonsmokers). The groups were equivalent in age, gender, education, and intelligence quotient. Two multiecho magnetization-prepared rapid acquisition with gradient echo (MP-RAGE) scans were collected for all participants using a 3T magnetic resonance imaging scanner with a 32 channel head coil. Brain volumes for each gray and white matter region of interest were derived using FreeSurfer. Participants completed a battery of neuropsychological tests measuring intelligence quotient, memory, executive functions, personality variables, and affect.
Results: Compared to nonsmoking nonalcoholics, alcoholics who smoke (the comorbid group) had volumetric abnormalities in: pre- and para-central frontal cortical areas and rostral middle frontal white matter; parahippocampal and temporal pole regions; the amygdala; the pallidum; the ventral diencephalic region; and the lateral ventricle. The comorbid group performed worse than nonsmoking nonalcoholics on tests of executive functioning and on visually-based memory tests. History of alcoholism was associated with higher neuroticism scores among smokers, and current smoking was associated with higher sensation seeking scores and lower extraversion scores among nonalcoholics.
Conclusion: Results from this exploratory study support and extend prior reports showing that alcoholism and smoking, alone and in combination, are associated with structural brain abnormalities and poorer performance on neuropsychological tests. Therefore, it is important to consider smoking status in alcoholism studies and vice versa.

Keywords: MRI, morphometry, neuropsychology, tobacco, alcohol