Depressives at an increase risk for Alzheimer's

According to researchers in Holland people who are depressed are at an increased risk of developing Alzheimer's disease.

The team from Erasmus University Medical Center in Rotterdam say people who suffer from depression are more than twice as likely to be diagnosed with Alzheimer's disease than are those not diagnosed with depression.

They also suggest that developing depression before age 60 puts the risk at 4 times more likely.

The researchers arrived at this conclusion after tracking 486 people between the ages of 60 and 90 for an average of six years; of the group 33 people developed Alzheimer's.

Depression has been linked to loss of brain cells, so people who have had depression may be more prone to Alzheimer's disease.

Lead researcher Dr. Monique Breteler says it is unclear whether depression contributes to the development of Alzheimer's disease, or whether another unknown factor causes both depression and dementia.

Dr. Breteler says the findings do not support the notion that depression leads to loss of hippocampus and amygdala cells which then leads to Alzheimer's.

Another study by researchers from Rush University in the U.S. followed more than 900 members of the Catholic clergy for up to 13 years during which time 190 developed Alzheimer's.

This research also found that those with more signs of depression at the start of the study were more likely to develop Alzheimer's.

Researcher Dr. Robert Wilson says depressive symptoms may be associated with distinctive changes in the brain that somehow reduce neural reserve, which is the brain's ability to tolerate the pathology associated with Alzheimer's disease.

Experts say more research is needed to clarify the relationship between dementia and depression in order to determine whether depression causes changes in the brain that make dementia more likely.

The researchers say their findings suggest that depression is a risk factor for Alzheimer's disease rather than a covert sign of its underlying pathology.

The studies are published in Neurology and the Archives of General Psychiatry.