"It is noteworthy that areas of the brain that are essential to memory and problem-solving are also responsive to cortisol," write Andrea C. King, Ph.D., of the University of Chicago and her colleagues. "It is possible that frequent exposure to high levels of cortisol during bouts of heavy drinking and subsequent withdrawals may have affected these areas in alcoholics and contributed to their deficits."
King and her colleagues recruited 48 male alcoholics receiving inpatient treatment for alcoholism and 30 nonalcoholic control participants. The alcoholics' cortisol levels were initially measured from a blood sample drawn the first morning after their admission to the treatment program; they participated in the remainder of the study protocol at the end of their inpatient treatment, which lasted 21 to 28 days.
Both the alcoholic and the control participants were assessed for memory and problem-solving ability using several standard tests and then performed two tasks known to induce stress: mental arithmetic problems and a "cold pressor" task, which requires submerging one hand in ice water for 90 seconds. Blood samples were drawn at intervals before, during and after the test, and cortisol levels were measured in each sample.
Although the men in both groups had nearly identical cortisol levels when the experiment began, the alcoholics demonstrated a "blunted" cortisol response after the stressors were administered. At 30 minutes after the test, the alcoholics' cortisol level was significantly lower than that of the control participants. The researchers compared the scores on the memory and problem-solving tasks with the cortisol response and found several patterns.
Among alcoholics, they found, the number of withdrawals from alcohol was the strongest predictor of memory impairments, but not of problem-solving ability. The greater the alcoholics' relative cortisol levels were during alcohol withdrawal, the more likely they were to have low scores on one of the problem-solving tests.
Also, the alcoholics' reduced cortisol responses were significantly linked to low scores on problem-solving tests. Nonalcoholic participants showed a connection between higher post-stress cortisol levels and impaired memory, a finding supported by earlier research.
The researchers add that although alcoholics tend to develop cognitive deficits as a result of alcohol-related health consequences such as liver disease or endocrine dysfunction, the findings of this study could possibly reflect problems with the endocrine or central nervous systems existing before the onset of alcoholism. They note that "future studies should examine such factors, in addition to heavy drinking history, in studies of [endocrine] dysregulation and memory deficits."
"The results may provide leads for future studies of the role of endocrine dysregulation and cognitive impairment in alcoholism," the researchers say. They caution that at this point, "the potential relationships between cognitive deficits and indicators of abnormal cortisol secretion in the alcoholics must be viewed as preliminary."
The study was supported by the Oklahoma Center for the Advancement of Science and Technology, the Medical Research Service of the Department of Veterans Affairs, and the Research Council of the Department of Psychiatry and Behavioral Sciences.
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