Parkinson’s disease patients often suffer from depression and both conditions are associated with low levels of serotonin. However, it had not been shown that depression could precede the symptoms of Parkinson’s.

Dr Agnes Schuurman and colleagues from Maastricht University in the Netherlands questioned whether depression could be the first symptom of Parkinson’s disease.

They identified all individuals on a health registry in the southern part of the country who were diagnosed with depression over a 15-year period.

These 1,358 individuals with a history of depression were then matched with 67,570 people in the registry who had been born in the same year but had no history of depression.

Dr Schuurman’s team followed these individuals for up to 25 years and recorded the prevalence of Parkinson’s disease.

Nineteen, or 1.4 per cent, of the depressed people went on to develop Parkinson’s disease, compared to only 259, or 0.4 per cent, of the non-depressed group.

The researchers believe that low serotonin levels are the link between depression and Parkinson’s disease. Serotonin acts to modulate the release of dopamine in the brain and, because dopamine activity is decreased in Parkinson’s disease, the scientists suggest that serotonin activity might also be decreased in compensation.

“Because the reduced serotonin activity already exists before any motor symptoms begin, the risk of depression is also increased long before any Parkinson’s symptoms become apparent,” said Dr Schuurman.

Reference: Schuurman et al, Neurology 2002;58:1501-1504

© Health Media Ltd 2002
http://www.health-news.co.uk