With statistics showing that at least 50% of adults in the US are regular alcohol drinkers (drinkers who have consumed 12 drinks or more in the past year¹), alcohol clearly remains the drug of choice for most Americans. While moderate alcohol use is not deemed dangerous, and is likely even healthy², it is nevertheless still important to know how chemicals we put in our bodies affect us. Many people know and often hear about alcohol abuse and its effects on the liver, the broad effects of alcohol use on other bodily systems, especially the brain, don’t seem to get that much attention. In the tradition of our other brain-addiction articles, we aim to do just that.

Alcohol use and brain depression

In a nutshell, alcohol depresses the central nervous system, causing the uninhibited, relaxed feeling that even the most casual drinker is familiar with. It does so mainly by interrupting brain communication – suppressing the excitatory nerve pathway (by affecting glutamate) and increasing the inhibitory activity (by affecting GABA).

Glutamate is the major excitatory neurotransmitter in the brain – it’s the one that commonly turns certain brain cells on and increases their firing activity. When alcohol is consumed it inhibits glutamate activity, which diminishes the excitatory effect of glutamate and reduces important relevant functions.

GABA is the major inhibitory neurotransmitter in the brain – it reduces firing activity and generally turns targets off. When alcohol is consumed it enhances GABA’s inhibition, which is always present throughout the brain to some extent, by directly increasing the activity of many GABA releasing neurons.

In short, alcohol use simultaneously suppresses important new brain activity and inhibits ongoing function at the same time, resulting in an intense depressive effect.

Interference with these two neurotransmitters, some of the most common ones found in the brain, is the reason for alcohol’s wide-ranging effects, particularly on the memory, which depends on the activation, by glutamate, of two receptor types – AMPA and NMDA. Without them, there’s no learning- and no memory (blackout anyone?).

The effects of alcohol use on behavior

By interfering with brain function, alcohol use lowers inhibitions, allowing drinkers to be more outgoing (and willing to do things they most likely otherwise wouldn’t). Information processing is also compromised when drinking, mostly due to alcohol’s effects on the cerebral cortex (and glutamate which is responsible for everything from seeing, to hearing, and more). This is the part of the brain which takes in a person’s senses and thoughts, and helps with voluntary muscle movements. Alcohol use causes impaired thoughts, poor judgment, and a higher threshold for pain. What you’re left with is someone who is slower and less thoughtful, but feels stronger and smarter, all while experiencing less pain. This is, of course, a dangerous combination.

Alcohol use also can influence a person’s cerebellum and limbic system, which control coordination, and emotional regulation, respectively. We’ve all seen those brave-drunks – normally shy individuals who get a little liquid courage in them and are suddenly the life of the party, all while barely being able to put one foot in front of the other. This is a great example of alcohol’s effect on the limbic system as well as the cerebellum. When the limbic system is impaired, individuals often experience memory loss, especially when it comes to emotional states and experiences. Limbic system dysfunction can also lead to individuals experiencing exaggerated feelings (the “I LOVE you, man!” effect). Cerebellum problems lead to a lack of muscle control and fine motor movements – just what you want when you’re trying to steer a car at 65 miles per hour and stay on the road.

The alcohol-sex connection

Due to its effect on the hypothalamus, alcohol use also plays a role in decreasing a person’s sexual desire and performance. The hypothalamus, along with the medulla, plays a role in controlling many regulatory functions of the brain and body. The hypothalamus is the control center for much of the body’s hormone function and governs the autonomic nervous system. The hypothalamus is part of the system than keeps the body in homeostasis, a balanced state that can be considered the “baseline” of system function. In this role, the hypothalamus organizes and controls many complex emotions, feelings and motivational states. The neurons in the hypothalamus produce a number of neurotransmitters which give instructions to different parts of the body.

When this neurotransmitter function get impaired, these systems get depressed, which lowers sexual desire and performance as well as causing individuals to become sleepy- at which point sexual performance doesn’t really matter anymore.

A parting gift – what alcohol abuse may leave users with long-term

As we mentioned above, many people only hear about how alcohol abuse can cause liver damage. But alcohol can do so much more damage than that and since this stuff is commonly used as a solvent (chemistry class anyone?!) that’s not really surprising. There is plenty of emerging research touting the positive effects of moderate alcohol consumption. However, if an individual continuously drinks to excess, there are serious long-term implications for that person’s memory, sex drive, and overall cognitive functions that can, and for more than 27,00 people a year does, end in death. So if alcohol use isn’t a problem for you, enjoy your glass of red wine (or micro-brew), but be aware of the effects; if alcohol abuse is an issue, you might as well keep everything operating as well as possible and stay away altogether.

Citations:

CDC Source: Summary Health Statistics for U.S. Adults: National Health Interview Survey, 2008, table 27.

Charles J. Holahan, Kathleen K. Schutte, Penny L. Brennan, Carole K. Holahan, Bernice S. Moos, Rudolf H. Moos (2010). Late life alcohol consumption and 20-year mortality. Alcohol Clinical & Experimental Research.