Children of alcoholics have an altered brain chemistry that appears to make them more likely to become alcoholics themselves, according to a recent study by Johns Hopkins scientists.
Using a drug-based technique that highlights differences in natural opioid activity in the brain, the researchers found such activity was significantly less in the young adults they studied from strongly alcoholic families.
"This is the first evidence that the brains of the non-alcoholic children of alcoholics differ in the activity of specific brain circuits most scientists link with alcoholism, and that those differences exist before the onset of heavy drinking," says neuroendocrinologist Gary S. Wand, M.D., who led a team of Hopkins researchers. The study was reported in the December Annals of General Psychiatry.
"This single difference in opioid activity may make people more vulnerable to alcoholism for two reasons," says Wand: "It alters the brain's reward/craving pathway and it also changes the brain's response to stress." Scientists have long suggested the reward pathway -- well-endowed with opioid receptors -- is key in alcoholism. "And we know that stress is involved in many kinds of drug-seeking behavior," he adds.
The difference could serve as a marker to predict family members at increased risk of alcoholism, Wand says.
The researchers compared 26 young adults with a strong family history of chronic drinking -- all had at least fathers who were alcoholics -- with 22 counterparts who had no such history. The scientists indirectly measured opioid activity in the brain by artificially blocking opioids in both groups with a drug called naloxone and then measuring the "downstream" effect on blood levels of cortisol, a hormone the body releases in response to stress. The differences in cortisol and, hence, in opioid activity between the two groups were significant.
By focusing on the brain chemistry of people related to alcoholics who've developed no alcohol problems themselves, Wand says, the research gets around a major bugaboo of research on that topic: how to find if abnormalities in the brains of alcoholics are built-in or if they come as a result of heavy drinking. "This study weighs in favor of the former."
The study also offers still another connection between brain chemistry and predisposition to alcoholism, says Wand: In elevated amounts, cortisol, the stress hormone, is thought to increase growth of the brain's reward system, making it easier for drugs of abuse to stimulate it. Cortisol is probably increased in those prone to alcoholism. "So someone who has a small drink would get a bigger reward from the overdeveloped system; the reward gets amplified," says Wand.
"These children of alcoholics may have a double-whammy," he says. "They have a flawed response to stress and additionally may have heightened drug rewards in the brain."
The research was funded by an NIH grant, by The Alcohol Medical Research Foundation, and by a gift from the Kenneth Lattman Foundation. Collaborators in the work are Samer El Deiry, M.D., Ph.D., Mary E. McCaul, Ph.d., Donald Hoover, Ph.D., and Deborah Mangold, M.A.
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