Scientists say they have established a link between depression and Alzheimer's disease, the mind robbing ailment suffered by former U.S. President Ronald Reagan and millions of others. In this week's issue of the journal Neurology, scientists report that elderly individuals who suffer from severe depression are much more likely to develop Alzheimer's.
More than 650 priests, nuns and brothers over the age of 65, who are part of what's known as the Religious Orders Study, took part in the seven year study.
The project included annual neurological evaluations and tests of memory and thinking, since impaired short term memory is one of the first symptoms of Alzheimer's.
At the start of the study, about half of the participants had no depressive symptoms. The other half exhibited between one and eight symptoms.
At the end of the end of the study, according to study author Robert Wilson of the Rush Alzheimer's Disease Center in Chicago, Illinois, 108 of the 650 participants had developed Alzheimer's disease.
"There was about a twenty percent increase in the risk of Alzheimer's disease with each symptom reported at the beginning of the study," he explained. "So we concluded from that the depressive symptoms in older persons do indeed appear to be related to the risk of developing Alzheimer's disease."
Mr. Wilson, a specialist in measuring memory function in old age, points out it's difficult to say why there appears to be a connection between depression and Alzheimer's.
"It's important to understand that the pathology of Alzheimer's disease is commonly found in the brains of older people who die, but not of all those people have the symptoms of Alzheimer's disease," he said. "So, it remains possible that through some physiological mechanism that we do not understand or psychological mechanism or both, the depressive symptoms might be an indication of how well a person is fighting off the symptoms."
Mr. Wilson added there's been controversy among experts about a link between Alzheimer's and depression. "I think our study provides some of the most solid evidence to date that there really is an association," he said. "And I think in our mind it suggests that we need to do the studies necessary to understand the basis of that association, and whether or not in some ways it may provide some clue this terrible disease and its disabling effects."
The study on Alzheimer's disease and depression is published in the August 13 issue of Neurology, a journal of the American Academy of Neurology.