Interactive effects of chronic cigarette smoking and age on hippocampal volumes.
BACKGROUND
Previous cross-sectional MRI studies with healthy, young-to-middle-aged adults reported no significant differences between smokers and non-smokers on total hippocampal volume. However, these studies did not specifically test for greater age-related volume loss in the total hippocampus or hippocampal subregions in smokers, and did they did not examine relationships between hippocampal and subfield volumes and episodic learning and memory performance.


METHODS
Healthy, young-to-middle-aged (45 ± 12 years of age) smokers (n=39) and non-smokers (n=43) were compared on total hippocampal and subfield volumes derived from high-resolution 4 Tesla MRI, emphasizing testing for greater age-related volume losses in smokers. Associations between hippocampal volumes and measures of episodic learning and memory were examined.


RESULTS
Smokers showed significantly smaller volumes, as well as greater volume loss with increasing age than non-smokers in the bilateral total hippocampus and multiple subfields. In smokers, greater pack-years were associated with smaller volumes of the total hippocampus, presubiculum, and subiculum. In the entire cohort, performance on measures of learning and memory was related to larger total hippocampal and several subfield volumes, predominately in the left hemisphere.


CONCLUSIONS
Chronic cigarette smoking in this young-to-middle aged cohort was associated with smaller total hippocampal and subfield volumes, which were exacerbated by advancing age. Findings also indicated an adverse smoking dose/duration response (i.e., pack-years) with total hippocampal and select subfield volumes. These hippocampal volume abnormalities in smokers may be related to the deficiencies in episodic learning and memory in young-to-middle-aged smokers reported in previous studies.
Center for Imaging of Neurodegenerative Diseases (CIND), San Francisco VA Medical Center, San Francisco, CA, USA; Department of Radiology and Biomedical Imaging, University of California, San Francisco, CA, USA. Electronic address: timothy.durazzo@ucsf.edu.
Timothy C
TC
Durazzo
Dieter J
DJ
Meyerhoff
Sara Jo
SJ
Nixon
D000328:Adult; D000368:Aged; D000375:Aging / Q000473:pathology; D000428:Alcohol Drinking / Q000473:pathology; D056547:CA1 Region, Hippocampal / Q000473:pathology; D056651:CA2 Region, Hippocampal / Q000473:pathology; D003071:Cognition / Q000502:physiology; D018891:Dentate Gyrus / Q000473:pathology; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007858:Learning / Q000187:drug effects; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000187:drug effects; D001523:Mental Disorders / Q000473:pathology; D008875:Middle Aged; D009483:Neuropsychological Tests; D012907:Smoking / Q000473:pathology* / Q000523:psychology
Aging; Cigarette smoking; Hippocampal subfields; Hippocampus; Learning and memory; MRI