Wednesday, January 26, 2011

Alcohol and the Brain

"While the history of alcohol use dates back thousands of years, the chemistry of alcohol metabolism - what actually takes place in the body when we imbibe - is only now becoming clear. Indeed, our understanding of alcohol’s toxic effects is still evolving. We know, for example, that the liver is uniquely susceptible to injury from alcohol, as it is the organ primarily responsible for metabolizing toxins entering the bloodstream. While evidence suggests that drinking in moderation may confer modest cardiovascular benefits, make no mistake - generally speaking, alcohol is toxic to living cells." Dale Kiefer in a publication called "A Little Known Fact: Alcohol is a Carcinogen"

To drink or not to drink?

Information about alcohol and its impact on brain health and health in general, can be confusing at times. In many publications we read that people who drink two drinks a day are healthier, live longer, and have lower risk of Alzheimer's and cardiovascular disease than heavy drinkers or those who do not drink at all. Other findings present evidence that any amount of alcohol is detrimental to brain health. Alcohol affects many parts of the brain. It has adverse effect on the brain tissue and it also depresses the central nervous system. What are we to make out of such conflicting reports?


The effects of alcohol are quite obvious after just a few drinks, although men seem to tolerate higher amounts of alcohol than women. Blurred vision, distorted speech, slower reaction time, impaired memory function, and distorted motor function, are the most immediate and noticeable effects of alcohol on the brain and the amount of alcohol that causes such impairments is rather minimal. Some people do not even need to drink much to reach the state of complete inebriation.

Alcohol and brain physiology

Ethyl alcohol, or ethanol, is the alcohol that is commonly consumed in alcoholic drinks. Once ingested, alcohol is not digested like other foods or drinks. It is calculated that about 20 percent of ingested alcohol bypass the digestive system and enter the bloodstream directly through the stomach wall. The remaining 80 percent is absorbed through the wall of the small intestine. The brain needs a constant supply of blood and is quite vulnerable to the effects of ethanol. Within minutes of alcohol consumption, the brain receives blood that is infused with alcohol. Alcohol interferes with communication between neurons by interacting with the receptors on some cells. Alcohol suppresses excitatory nerve pathway activity, increasing at the same time the inhibitory nerve pathway activity. This enhances the activity of the inhibitory neurotransmitter GABA and diminishes the excitatory neurotransmitter glutamine. As a consequence, a person under the influence of alcohol experiences sluggishness. Moreover, acetaldehyde which is a toxic by-product of alcohol metabolism, can cross the blood-brain barrier and cause irritation of brain membranes. This not only leads to headaches and hangover, but also increases the risk of developing a cancer.

Excessive drinking increases the exposure to acetaldehyd. This can cause brain fog, memory lapses, mood swings, irritability, and loss of motivation. But probably the most damaging effect of alcohol in the brain is caused by the free radicals produced during the metabolism of alcohol. Free radicals destroy cell membranes in a process called lipid peroxidation and precipitate the aging of the brain. Research demonstrated that the concentrations of creatine and choline in the brain diminish with the increasing levels of alcohol. Creatine protects the brain cells and choline is a building component of cell membranes. Diminished amounts of these compounds in the brain leave this organ vulnerable to damage. Autopsies show that people who abused alcohol had smaller and more shrunken brains than abstinent adults of the same age and gender.

In order to function properly, the brain needs a steady supply of glucose. In July 2009 researchers found out that even relatively small amounts of alcohol cause changes in the sugar that is being delivered to the brain. The brain's activity diminishes as it begins to run on the sugar derived from alcohol instead of the glucose that it normally uses.

Research also shows that alcohol does not destroy the entire brain cells, but damages dendrites which are responsible for the delivery of the incoming information to the brain. In moderate drinkers this damage is temporary. The dendrites grow back, but the brain cell structure is altered permanently. After a period of abstinence, the brain cells seem to regenerate even in the brains of alcoholics. However, scientist are still trying to figure out the impact of these altered structures on the brain function.

Alcohol and cognition

The American Journal of Epidemiology announced in 2005 that some observational studies suggested improved cognitive function and reduced risk of cognitive decline and dementia in moderate drinkers. But research also shows that heavy alcohol consumption impairs the cognitive function. People who abuse alcohol have impaired memory and diminished reasoning ability. Although less dramatically, the cognitive function is also affected in people who consider themselves to be social drinkers. Tests demonstrated some deficits in cognitive performance that could be correlated to the amount of alcohol consumed. The findings, however, are inconsistent as there are other studies that show no correlation between alcohol consumption and the cognitive impairment. Researchers generally agree, though, that some cognitive impairment in alcoholics is reversible. Three factors may play a role here: abstinence from alcohol, better nutrition, and improved social interaction. However, the skills that require novel, complex, and rapid information processing take the longest time to recover.

Heavy, long-term abuse of alcohol is associated with the Wernicke-Korsakoff syndrome in which deficiency of Vitamin B1 (thiamine) is responsible for a number of symptoms including confusion and dementia. Alcohol interferes with the active gastrointestinal transport of Thiamine. In addition, a chronic liver disease in heavy drinkers interferes with thiamine metabolism and the liver's capacity to store this vitamin. The chronic lack of Vitamin B1 impacts the memory centers in the brain. A person may suffer from memory loss or loses the ability to form new memories. Loss of muscle coordination, changes in vision, and hallucinations have been observed as well.

Alcohol and Alzheimer's Disease

As far as Alzheimer's disease is concerned, findings are inconclusive. While some researchers insist that alcohol consumption impairs cognition and causes damage to brain tissue, others demonstrated that moderate alcohol use actually lowered the risk of developing Alzheimer's disease. It is possible that alcoholic dementia and Alzheimer's disease are caused by factors that are not yet understood. An ongoing research is being conducted and we may learn more about the Alzheimer's-alcohol connection in the near future.

Alcohol and stroke

The most recent studies demonstrated that alcohol consumption is related to the incidence of stroke. The higher the consumption of alcohol, the higher the risk of stroke. This is true for both, the ischemic (due to lack of glucose and oxygen supply to the brain) and the hemorrhagic (due to bleeding) types of stoke. However, research showed that moderate drinking may protect individuals against the ischemic stroke. There is also an evidence that women benefit more than man from the moderate alcohol consumption. Alcohol seems to inhibit coagulation and rise the HDL or high-density lipoprotein commonly known as the good cholesterol. Both factors are associated with lowered risk of ischemic stroke. However, the fact that alcohol inhibits coagulation and rises blood pressure may directly lead to the increased risk of the hemorrhagic stroke.

Alcohol and brain development

There is no safe dosage of alcohol for pregnant women. Women who drink alcohol during pregnancy increase the risk of miscarriage and still birth. They give births to smaller children with the so called Fetal Alcohol Syndrome. Alcohol impedes the normal physical and mental development of a child. Children whose mothers drunk alcohol during pregnancy have a developmental delay and often show signs of mental retardation. The physical effects of alcohol may vary from infant to infant and depend on the amount of alcohol consumed during pregnancy, but all infants show abnormal brain and behavioral development. This fact must be seriously considered by all women who are pregnant or trying to conceive a child.

Conclusion

Alcohol affects every organ of the body and deprives the body of nutrients. The consequences are more severe in people who regularly abuse alcohol, but so called social drinkers experience noticeable changes in behavior and motor function even after moderate consumption of alcohol. All researchers agree that alcohol consumed in large quantities over a long period of time is detrimental to health in general and brain health in particular. However, researchers found out that even the brain of a former alcoholic has the capability to regenerate itself to a certain degree. The current theory is that people can only profit from small amounts of alcohol. Scientific medical research demonstrated that moderate alcohol consumption improves thinking, reasoning, and memory in aging adults. It is up to every individual to decide for or against the alcohol consumption. Active lifestyle and wholesome nutrition are vital independently from the choices made.

By Dominique Allmon

This information is for educational purpose only. It is not meant to diagnose or cure a disease.

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