Be careful, depression may lead to Alzheimer's.

People who have depression are more likely to get Alzheimer's disease than people who never depressed.  This is the result of a study published on 8 April 2008, issue of Science Daily quoted Neurology.

The study involved 486 people age 60 to 90 who did not have dementia.  134 people known to have experienced a period of depression, thus making them seek medical assistance.

The participants were observed for an average of six years.  During that time 33 people suffering from Alzheimer's disease.  People who were depressed were 2.5 times more likely to develop Alzheimer's disease than people who had never been depressed.  The risk was even higher for those with depression before age 60. They were nearly four times more likely to have Alzheimer's than those without depression.

According to Monique MB Breteler, MD, PhD, of University Medical Center in Rotterdam, the Netherlands, they do not know yet whether depression contributes to the development of Alzheimer's disease or whether another unknown factor causes depression and dementia.  They still have to do more studies to understand the relationship between depression and dementia.

One theory that may be known is that depression can lead to loss of cells in two regions of the brain, the hippocampus and amygdala, which then contribute to Alzheimer's disease.  Although in this study found no difference in the size of the two regions of the brain among people with depression and those who had never been depressed.

The study also assessed whether participants had symptoms of depression at baseline.  However, people with depressive symptoms at baseline did not allow having Alzheimer's than those who were not depressed at baseline.

The research was supported by the Netherlands organization for Scientific Research and the Health Research and Development Council.