Scientists are still grappling with the question why only some people develop undue fondness for alcohol and become addicts, while others are able to keep within healthy limits. While alcoholism is known to run in families, it is not clear whether it is the effect of the environmental exposure from childhood or our genetic make up that makes us so.The role of genes became suspect when studies on identical twins, separated early in life and brought up in different homes were found to have a much higher chance of showing a similar pattern when traced in adulthood. If one was an alcoholic, then the other had a very high chance of being one too, even if separarted over long distances!
The search for the addiction gene has however not been easy: it has become increasingly clear in recent years that there me be as many as 20 genes that determine addiction, just as there could be severasl reasons why people drink.
It is common knowledge that anxious people find relaxation in drinks, and often tend to drink more during stress. Researchers from University of Illinois, Chicago have shown that inborn levels of anxiety, governed by some genes, could play a role in alcohol addiction. Says researcher Subhas Pandey, “Some 30-70% of alcoholics suffer from anxiety or depression, and drinking is a way for these individuals to self medicate”.
Pandey’s research focusses on the CREB gene, so called because it produces the protein CREB, that regulates brain function during development and learning and is involved in the process of alcohol tolerance, dependence and withdrawal symptoms. When there is less CREB protein in the part of the brain called amygdala, one experiences increased anxiety-like behaviour and preference for alcohol. Further, his study showed that rats deficient in CREB protein drank about 50% more alcohol than normal rats, and showed higher prefernce to alcohol over water.
Another mechanism for alcohol dependence could be sheer pleasure rather than anxiety-reduction. A group of researchers led by Dr Wofgang Sadee have found how differences in one gene can make the brain more sensitive to alcohol, narcotics and nicotine. The gene studied codes for a brain protein called opioid receptor, which acts like a switch turning on pleasure and blocking pain when triggered by alcohol or certain drugs. The 2 variations of the mu-opioid receptor gene A118G and G118, determine our response to morphine like drugs or morphine like chemicals naturally produced in the body that determine our individual sensitivities to pain and pleasure, and could well explain why some people find so much pleasure in alcohol while others do not. The increased sensitivity to alcohol and opioids could make these individuals highly susceptibe to addiction to these agents, and make withdrawal extremely painful.
These recent scientific revellations help explain why the same beer or whisky evokes such wide variations in response among individuals consuming them. Time has still not come for scientists to predict who might become an addict if he starts drinking and who should stay away. However the question of addiction was irrelevant when alcohol was a social taboo, but with its growing presence in parties and clubs, the “mother’s fear” has reasons for its return.
As published in HT City ( Hindustan Times) dated 4 april , 2010.
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