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How well (and how quickly) we age depends on a confluence of genetic, environmental, and lifestyle factors. Some lifestyle behaviors, such as alcohol consumption and cigarette smoking, elicit harmful effects on multiple body systems that can accumulate over time to modulate aging. A new study demonstrates that alcohol consumption and cigarette smoking accelerate brain aging, in particular.
Research indicates that smoking cigarettes alters multiple structural aspects of the brain. For example, smokers tend to have less gray matter density and volume in the frontal, occipital, and temporal lobes – areas related to a wide range of brain function. Similarly, heavy alcohol use is associated with reduced gray and white matter volumes in the medial-prefrontal and orbitofrontal cortices.
The authors of the study assessed relative brain age, a comparative measure of brain aging between people of the same chronological age, to determine if a person’s brain is aging at a different rate relative to their peers. The study was based on analysis of brain-imaging data collected from more than 17,000 UK Biobank participants who were of European ancestry and were cognitively normal. After determining the participants' relative brain age, they studied the association of relative brain age with cigarette smoking, alcohol consumption, and genetic variants.
They found that regular (daily or nearly daily) cigarette smoking or alcohol consumption increased relative brain aging. Every gram of alcohol (~20 grams in 1 fluid ounce) consumed per day was linked to one week of accelerated brain aging and each year spent smoking one pack of cigarettes per day was linked to 11 days of accelerated brain aging.
These increases in brain aging were associated with poor cognitive function and declines in fluid intelligence, the ability to creatively solve problems without prior knowledge or learning. They also identified two single nucleotide polymorphisms associated with accelerated brain aging.
While it is important to note that the effect of alcohol on brain aging was only seen in daily or almost daily drinkers, these findings provide useful insights into how cigarette smoking and alcohol consumption influence brain aging and highlight the need for future research to fully elucidate the factors associated with how the brain ages.