Alcohol-related brain damage alters both the structure and function of the brain as a result of the direct neurotoxic effects of alcohol intoxication or acute alcohol withdrawal. Increased alcohol intake is associated with damage to brain regions including the frontal lobe, limbic system, and cerebellum, with widespread cerebral atrophy, or brain shrinkage caused by neuron degeneration. This damage can be seen on neuroimaging scans.
Frontal lobe damage becomes the most prominent as alcoholics age and can lead to impaired neuropsychological performance in areas such as problem solving, good judgement, and goal-directed behaviors. Impaired emotional processing results from damage to the limbic system. This may lead to troubles recognizing emotional facial expressions and "interpreting nonverbal emotional cues".
Binge drinking, or heavy episodic drinking, can lead to damage in the limbic system that occurs after a relatively short period of time. This brain damage increases the risk of alcohol-related dementia, and abnormalities in mood and cognitive abilities. Binge drinkers also have an increased risk of developing chronic alcoholism. Alcoholism is a chronic relapsing disorder that can include extended periods of abstinence followed by relapse to heavy drinking. It is also associated with many other health problems including memory disorders, high blood pressure, muscle weakness, heart problems, anaemia, low immune function, liver disease, disorders of the digestive system, and pancreatic problems. It has also been correlated with depression, unemployment, and family problems with an increased risk of domestic abuse.
Gender and parental history of alcoholism and binge drinking has an influence on susceptibility to alcohol dependence as higher levels are typically seen in males and in those with a family history.
Prevalence
Nearly half of American alcoholics exhibit "neuropsychological disabilities [that] can range from mild to severe" with approximately two million requiring lifelong care after developing permanent and debilitating conditions. Prolonged alcohol abstinence can lead to an improvement in these disabilities. For those with mild impairments, some improvement has been seen within a year, but this can take much longer in those with higher severity damage.
Populations at risk
Adolescents and genetic factors
The impulsivity and sensation seeking seen in adolescence may lead to increased alcohol intake and more frequent binge drinking episodes leaving adolescents particularly at risk for alcoholism. The still developing brain of adolescents is more vulnerable to the damaging neurotoxic and neurodegenerative effects of alcohol. "High impulsivity has [also] been found in families with alcoholism, suggestive of a genetic link. Thus, the genetics of impulsivity overlaps with genetic risks for alcohol use disorder and possibly alcohol neurodegeneration".
There is also a genetic risk for proinflammatory cytokine mediated alcohol-related brain damage. There is evidence that variants of these genes are involved not only in contributing to brain damage but also to impulsivity and alcohol abuse. All three of these genetic traits contribute heavily to an alcohol use disorder.
Neurological deficits
Alcoholics can typically be divided into two categories, uncomplicated and complicated. Uncomplicated alcoholics do not have nutritional deficiency states or liver disease, but have a reduction in overall brain volume due to white matter cerebral atrophy. The severity of atrophy sustained from alcohol consumption is proportional to the rate and amount of alcohol consumed during a person's life. Complicated alcoholics may have liver damage that impacts brain structure and function and nutritional deficiencies "that can cause severe brain damage and dysfunction".
Pathophysiology
Adolescents are much more vulnerable to alcohol-related brain damage in the form of persistent changes in neuroimmune signalling from binge drinking. The endocrine system includes the hypothalamic–pituitary–adrenal axis, the hypothalamic–pituitary–gonadal axis, the hypothalamic–pituitary–thyroid axis, the hypothalamic–pituitary–growth hormone/insulin-like growth factor-1 axis, and the hypothalamic–posterior pituitary axis, as well as other sources of hormones, such as the endocrine pancreas and endocrine adipose tissue. Alcohol abuse disrupts all of these systems and causes hormonal disturbances that may result in various disorders, such as stress intolerance, reproductive dysfunction, thyroid problems, immune abnormalities, and psychological and behavioral disorders.