Alcohol and brain development

Alcohol can harm brain development and function, including by reducing brain tissue, weakening impulse control, and harming fetal development during pregnancy.

• One to two drinks daily: A study discussed in the episode found thinning of the neocortex and other brain regions among people averaging one or two drinks per day—about seven to fourteen drinks per week. 1
• Prefrontal-cortex inhibition: Alcohol suppresses prefrontal activity involved in planning and inhibiting impulses. With that top-down control diminished, impulsive and habitual behavior can increase, along with behavioral changes such as speaking or acting with less forethought. 2
• Pregnancy and fetal development: Alcohol passes to the fetus, and exposure can disrupt coordinated development. Fetal alcohol syndrome is associated with diminished brain development that may be permanent; the episode emphasizes that no type of alcohol is safe during pregnancy. 3 4
• Habit and impulsivity circuits: Regular drinking can strengthen circuits involved in habitual behavior and alter circuits supporting behavioral control, contributing to increased impulsivity even outside drinking periods. The episode says these changes can return toward normal after two to six months of abstinence, except that long-term heavy use may leave lasting effects. 5
• Gray-matter loss: Chronic alcohol use is associated with reduced cortical thickness and gray-matter volume; the episode describes brain shrinkage as increasing in a near dose-dependent relationship with alcohol consumption. 6