What Does Alcohol Do to Your Brain?

In the United States and most European nations, the majority of people have used alcohol by young adulthood (Substance Abuse and Mental Health Services Administration, 2007). This blog post will review what is known about how much alcohol use may affect brain functioning long after the intoxication effects have warn off.

About 50% of people who meet diagnostic criteria for alcoholism show some problems in thinking or memory (Oscar Berman & Marinkovic, 2003). The ability to plan ahead, withhold responses, learn and hold information, and work with spatial information (such as following a map) are particularly affected (Fein, Torres, Price, & Di Sclafani, 2006; Sullivan, Deshmukh, De Rosa, Rosenbloom, & Pfefferbaum, 2005; Sullivan, Fama, Rosenbloom, & Pfefferbaum, 2002). Even 15-16 year-olds with heavy drinking histories have shown problems in the ability to recall information that was previously learned (Brown, Tapert, Granholm, & Delis, 2000).

However, there is always the chicken and egg problem: what came first? It's possible that alcohol use doesn't actually cause these effects, and that these problems were actually there before, and they may in fact be a risk factor for developing alcohol abuse or dependence. What is important to keep in mind is that we have seen poorer performance over time among young people who continued a pattern of heavy alcohol use (Tapert, Granholm, Leedy, & Brown, 2002). Those who reported drinking so much at times that they experienced negative after-effects, or hangovers, were the most likely to go downhill over time, as compared to those who halted substance use (Tapert et al., 2002).

These findings are not just the results of individuals not trying hard enough on these tasks. The size and shape of brain structures are also abnormal in chronic heavy drinkers. The overall amount of gray matter (brain cells) and white matter (cabling between the cells) are reduced (Pfefferbaum et al., 1995), particularly in the frontal lobes, which are key parts of the brain for planning, withholding responses, making decisions, and regulating emotions. White matter is key for relaying information within the brain, and the coherence or quality of white matter tracts appears poorer in chronic heavy drinking adults (Pfefferbaum, Adalsteinsson, & Sullivan, 2006).

In adolescent heavy drinkers, we have seen, on average, smaller sizes of the hippocampus (a key region for learning new information) and portions of the frontal lobes (Medina et al., 2008; Medina, Schweinsburg, Cohen-Zion, Nagel, & Tapert, 2007; Nagel, Schweinsburg, Phan, & Tapert, 2005). Further, our preliminary studies have suggested that white matter quality is poorer in adolescents consuming as little as 20 drinks per month than in non-drinkers.

Taken together, there are clear differences between chronic heavy drinkers and non-drinkers in how the brain works. It appears that the brain of chronic drinkers has to "work harder" to keep things in mind, such as remembering a phone number, an address where you need to go, or a shopping list. In comparison, although we see similar changes in the brains of adolescents with only one to two years of heavy drinking, it appears that the young brain can compensate for any subtle alcohol-related disturbances by working other brain regions a little harder (Tapert, Pulido, Paulus, Schuckit, & Burke, 2004). However, if heavy drinking continues, by young adulthood the brain may not be able to compensate as effectively, and performance may begin to decline (Tapert et al., 2001).

On the other hand, the brains of adolescent heavy drinkers but not those of individuals who rarely drink spend much processing effort when they look at alcohol advertisements, relative to looking at non-alcohol beverage images (Tapert et al., 2003). Therefore, brains may become "sensitized" to processing alcohol related information once you get involved in drinking.

The bottom line is that research shows clearly that chronic use of heavy levels of alcohol is associated with adverse effects on the brain. The bad news is, if you want to reach your maximum potential with the brain you have, you should limit alcohol use to moderate levels (that is ≤1 drink for females and ≤2 drinks for males per occasion). The good news is that for people in recovery from alcohol problems, many difficulties with concentration and memory will improve substantially in the first month of recovery, and even throughout continued recovery as long as they stay away from alcohol.