Middle-aged smokers have smaller gray-matter volumes than their non-smoking peers, and the falloff is especially pronounced in the brains of smokers who also drink.
The finding comes from an MRI-based study led by members of the National Institute on Aging’s (NIA’s) epidemiology and population-science lab. The study was published online Feb. 11 in Translational Psychiatry.
In introducing their work, Lenore Launer, PhD, Martine Elbejjani, PhD, and colleagues noted that cigarette smoking previously has been associated with dementia and dementia-related brain changes, including atrophy of gray matter (GM).
Such changes are not surprising, given smoking’s established correlations with vascular and respiratory problems as well as substance-use tendencies. The present NIA study set out to analyze the extent and localization of the smoking-GM relationship and assess the degree to which vascular, respiratory and substance use/psychological factors influence this relationship.
The researchers examined associations of smoking status with total GM volume and GM volume of brain regions linked to neurocognitive and addiction disorder in 698 adults, mean age 50.3, who enrolled in the CARDIA study as young adults in the mid-1980s.
The team found that, compared to never-smokers, current smokers had smaller total GM volume. This association was diminished after the researchers adjusted for substance use/psychological—but not vascular or respiratory—factors.
As for the smoking-drinking connection, concurrent smoker-drinkers had smaller total and regional GM than non-drinkers. Affected regions included the frontal and temporal lobes, amygdala, cingulate and insula.
From this evidence the authors concluded that brain regions most vulnerable to diminished GM due to smoking and drinking are those in which cognition and addiction processes overlap.
The findings suggest “important connections between smoking and behavioral co-morbidities and brain regions linked to addiction processes at mid-life,” Launer et al. wrote. “Future research on smoking and brain health, as well as interventions to address smoking and alcohol use, should prioritize subjects who present with both cigarette smoking and alcohol use, as they appear to be at even greater risk for adverse brain outcomes.”
The study is available in full for free.