Excessive alcohol consumption can lead to disastrous health consequences. Heavy drinking increases the risk of injury, spousal or child abuse, risky sexual behaviors, and serious medical consequences such as alcoholic liver disease, high blood pressure, and gastrointestinal cancer. Chronic excessive drinking is particularly damaging to the brain and can increase the risk of dementia, stroke, and psychological disorders. However, drinking in moderation has many health benefits and is good for the brain. The U.S. Food and Drug Administration (FDA) defines “moderate drinking” as <1 standard drink per day for women and <2 standard drinks per day for men. In the U.S., a standard glass is 12 grams of ethanol, which is equivalent to the amount of ethanol in 12 ounces of regular beer, 5 ounces of 12-proof wine, and 1.2 ounces of distilled spirits. A recent survey from the U.S. Substance Abuse and Mental Health Administration (SAMHSA) showed that roughly 86.8 percent of people over the age of 18 have drank alcohol at some point in their lives, and 57 percent said their most recent drink was in the last month. Nearly a quarter of adults surveyed said they had consumed alcohol in the past month, which is defined as drinking 4 (women) or 5 (men) standardized glasses of alcohol in a 2-hour period. About 7% have an alcohol use disorder. A study from Columbia University shows that drinking gets worse, reporting that 3 out of 10 Americans may have a drinking problem or have abused alcohol at some point in the past. According to the National Centers for Disease Control and Prevention (CDC), excessive drinking is a significant cause of nearly 90,000 deaths in the U.S. each year and is the third leading cause of lifestyle-related deaths. How little alcohol is unsafe to consume is not safe, according to the 2014 World Health Organization World Cancer Report, which details a dose-dependent relationship between the amount of alcohol consumed and tumors of the oral cavity, pharynx, esophagus, colorectum, liver, breast, and pancreas. Other studies have shown that women with high risk factors for breast cancer who drink alcohol will significantly increase the density of mammography. The relationship between alcohol and the brain is complex. Many studies have shown that light to moderate alcohol consumption can prevent cardiovascular disease, an effect that can be attributed to ethanol itself and polyphenols with antioxidant properties. Red wine has the most benefits, while the benefits of beer, especially stout, are only legendary. Alcohol consumption has also been reported to have preventive and anti-inflammatory effects on atherosclerosis, and to improve cholesterol status, platelet coagulation, and insulin sensitivity, all of which can lead to neurological benefits. Light to moderate alcohol consumption is also thought to be associated with lower ischemic and hemorrhagic strokes. However, heavy drinking increases the risk of hemorrhagic stroke and more severe ischemic cerebrovascular events. It should be noted that many of the studies that have looked at the effects of ethanol on the cardiovascular system have been observational, and the researchers have not demonstrated a causal relationship. While moderate alcohol consumption may similarly reduce the risk of dementia, the cognitive damage of excessive alcohol consumption can be severe. a study published in Neurology in January 2014 showed that middle-aged adults who drank more than 2.5 standard glasses of alcohol per day had a higher risk of experiencing overall cognitive decline (especially memory) over a 10-year period. Notably, animal studies have shown that fish oil may provide some protection by slowing the neuronal degeneration caused by ethanol. Of greatest concern to society and the medical community is the effect of alcohol on the brains of children and adolescents, a Swedish study published in August 2013 in the journal JAMA Internal Medicine reported that of the nine influences that contribute to the onset of dementia in young patients, alcoholism had the most significant effect. In addition, 2012 MRI findings found that children born to mothers who drank heavily during pregnancy had significantly reduced brain plasticity compared to other children. Not only are certain patients with mental illnesses more likely to develop alcohol and substance abuse, but excessive alcohol consumption can also lead to mental illness, with about 1/3 of alcoholics suffering from mental illness. Alcohol is known to have considerable psychosocial effects, including increased risk of legal disputes, social and occupational barriers, domestic violence, and high risk of suicide. The psychiatric manifestations of alcohol may be mediated in part by its effects on neurotransmitter functioning, particularly loss of serotonergic functioning.A 2012 study found that women were far more susceptible than men to serotonergic disorders caused by excessive alcohol consumption. As with most substances of abuse, alcohol increases dopamine production in the limbic reward circuit of the central cortical branch. In social drinkers, subjective intoxication via intravenous ethanol injection activates reward circuits, including the nucleus accumbens. This activation process results in reduced subjective pleasure and responses to fear-based stimuli. In severe alcoholics, the activation of the nucleus accumbens caused by alcohol consumption is more subdued, suggesting a reduced pleasure response. When social drinkers make risky choices, ethanol enhances activation of the nucleus accumbens and reduces striatal, thalamic, and insula responses to positive or negative outcomes. In this way, under the influence of ethanol, the risky behavior itself, i.e., is more rewarding and the outcome is less important. The effects of ethanol on the brain are complex, with acute and chronic effects, involving multiple systems and varying widely by age and genetic factors. Moderate alcohol consumption can benefit the brain; however, the damage caused by mental, neurological, and other somatic conditions associated with alcohol consumption can instantly outweigh the benefits. Therefore, physicians should focus on the effects of alcohol abuse on the brain and general health and advance screening for alcohol abuse. As the ancient Greek proverb says, "Never do anything to excess."