Author: James Anderson

How Does Alcohol Affect the Brain?

This CME/CE credit opportunity is jointly provided by the Postgraduate Institute for Medicine and NIAAA. Differences between the two cerebral hemispheres can easily be seen in patients with damage to one hemisphere but not the other (from stroke, trauma, or tumor). Patients with left hemispheric damage often have problems with language; patients with right hemispheric damage often have difficulty with maps, designs, music, and other nonlinguistic materials, and they may show emotional apathy. Schematic drawing of the human brain, showing regions vulnerable to alcoholism-related abnormalities. Consumption of alcohol has and continues to serve major roles in religious and cultural ceremonies around the world.

1. There is evidence that the frontal lobes are particularly vulnerable to alcoholism-related damage, and the brain changes in these areas are most prominent as alcoholics age (Oscar-Berman 2000; Pfefferbaum et al. 1997; Sullivan 2000) (see figure 2).
2. One example of this mapping involves glucose, the main energy source for the brain.
3. “If you’re using alcohol to cope with stress or anxiety, if you’re going out and intending to drink one drink and you’re not able to stop yourself from drinking, it’s important to talk to your doctor and meet with a specialist,” encourages Dr. Anand.

Additionally, excess alcohol is defined as drinking more than 8 drinks a week (women) and 15 a week (men), or consuming alcohol if you are pregnant or younger than age 21. When people talk about drinking “alcohol,” they’re almost always referring to the consumption of ethanol. Ethanol is a natural product that is formed from the fermentation of grains, fruits, and other sources of sugar. It’s found in a wide range of alcoholic beverages including beer, wine, and spirits like vodka, whiskey, rum, and gin. If you do choose to drink, your body’s response to alcohol depends on many factors.

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Alcohol can disrupt fetal development at any stage during a pregnancy—including at the earliest stages and before a woman knows she is pregnant. Alcohol interferes with the brain’s communication pathways and can affect the way the brain looks and works. Alcohol makes it harder for the brain areas controlling balance, memory, speech, and judgment to do their jobs, resulting in a higher likelihood of injuries and other negative outcomes. Long-term heavy drinking causes alterations in the neurons, such as reductions in their size. Alcohol misuse can lead to neurological damage that can affect multiple areas of a person’s health and well-being.

The major excitatory neurotransmitter in the human brain is the amino acid glutamate. Small amounts of alcohol have been shown to interfere with glutamate action. During alcohol withdrawal, glutamate receptors that have adapted to the long-term presence of alcohol may become overactive, and this overactivity has been repeatedly linked to neuronal death, which is manifested by conditions such as stroke and seizures. Deficiencies of thiamine caused by malnutrition may contribute to this potentially destructive overactivity (Crews 2000). There is evidence that the frontal lobes are particularly vulnerable to alcoholism-related damage, and the brain changes in these areas are most prominent as alcoholics age (Oscar-Berman 2000; Pfefferbaum et al. 1997; Sullivan 2000) (see figure 2). Alcoholics may seem emotionally “flat” (i.e., they are less reactive to emotionally charged situations), and may have difficulty with the same kinds of tasks that patients with damage to the right hemisphere have difficulty with.

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But according to the Centers for Disease Control and Prevention (CDC), drinking less or not at all may help you avoid neurological harm. Consuming too much, especially over months or years, can result in severe symptoms. More resources for a variety of healthcare professionals can be found in the Additional Links for Patient Care. 2Some people may have better immunity than others to alcohol’s toxic effects. If you’ve ever wondered what’s really going on in the brain when a person’s had too much to drink, here’s a brief primer. If you drink for long periods of time, it can cause depression, and when you abruptly stop drinking, it can cause anxiety,” says Dr. Anand.

In spite of their excellent spatial resolution—that is, the ability to show precisely where the activation changes are occurring in the brain—hemodynamic methods such as PET, SPECT, and fMRI have limitations in showing the time sequence of these changes. Activation maps can reveal brain areas involved in a particular task, but they cannot show exactly when these areas made their respective contributions. This is because they measure hemodynamic changes (blood flow and oxygenation), indicating the neuronal activation only indirectly and with a lag of more than a second.

Available evidence suggests that alcohol3 initially potentiates GABA’s effects (i.e., it increases inhibition, and often the brain becomes mildly sedated). However, over time, prolonged, excessive alcohol consumption reduces the number of GABA receptors. When the person stops drinking, decreased inhibition combined with a deficiency of GABA receptors may contribute to overexcitation throughout the brain.

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Adolescent brains are more vulnerable to the negative effects of alcohol than adult brains. Misuse of alcohol during adolescence can alter brain development, potentially resulting in long-lasting changes in brain structure and function. Females can be more susceptible than males to many of the negative consequences of alcohol use, such as nerve damage, as they may begin to see effects from a lower amount of alcohol consumption. Together, medication and behavioral health treatments can facilitate functional brain recovery. In short, alcohol use during adolescence can interfere with structural and functional brain development and increase the risk for AUD not only during adolescence but also into adulthood. To help clinicians prevent alcohol-related harm in adolescents, NIAAA developed a clinician’s guide that provides a quick and effective screening tool (see Resources below).

Some of the previously mentioned factors that are thought to influence how alcoholism affects the brain and behavior have been developed into specific models or hypotheses to explain the variability in alcoholism-related brain deficits. It should be noted that the models that focus on individual characteristics cannot be totally separated from models that emphasize affected brain systems because all of these factors are interrelated. Several of the models have been evaluated using specialized tests that enable researchers to make inferences about the type and extent of brain abnormalities. “I’ve seen cases where I wouldn’t recognize a patient based on how they’re acting.” Brain damage (and symptoms like brain fog) can also be caused by cirrhosis of the liver, another common complication of long-term, heavy drinking.

An alternate version suggests that older patients (age 50 and older) are especially susceptible to the cumulative effects of alcoholism, and aging is accelerated only later in life. The preponderance of scientific evidence suggests that although alcoholism-related brain changes may mimic some of the changes seen in older people, alcoholism does not cause premature aging. Rather, the effects of alcoholism are disproportionately expressed in older alcoholics (Oscar-Berman 2000). Whether or not a person engages in drinking should be a decision they make on their own, or with the help of a doctor or mental health professional. For many people without a history of dependence or addiction, Pagano said, drinking at low or moderate levels—no more than seven drinks a week for women, and no more than 14 a week for men—can be a healthy part of life. That number jumped to four or five years for those who had 18 drinks or more per week.

People who drink regularly may also notice that booze doesn’t have the same effect on them as it used to. “With chronic drinking, the wiring element to your brain’s reward system can get worn out and lose some of its normal functioning,” said Pagano. “You build up a tolerance, and after a while, you don’t feel as good as you once did with the same amounts of alcohol.” While definitions can be variable, one way to look at this is the consumption of 4 or more drinks on an occasion (for women) and 5 or more for men.