Study Finds Depression Ups Risk of Parkinson's Disease

A new study has linked Parkinson's disease and depression confirming earlier made observations.

Researchers in Sweden found that depression increased risk of Parkinson's by 1.1 percent as against 0.4 percent in people without depression. The study's findings were based on all Swedes aged over 50 years with depression. Researchers followed participants for up to 26 years and found that 1,485 people with depression developed Parkinson's while 1,775 without depression develop the condition.

"We saw this link between depression and Parkinson's disease during over a timespan of more than two decades, so depression may be a very early symptom of Parkinson's disease or a risk factor for the disease," said one of the study authors Helena Gustafsson, at Umea University.

Though it study did not show a causal relationship, the study's findings are significant given the sample size. Researchers also examined prevalence of depression and Parkinson's in siblings, finding no underlying genetic link for the two.

"This finding gives us more evidence that these two diseases are linked. If the diseases were independent of each other but caused by the same genetic or early environmental factors, then we would expect to see the two diseases group together in siblings, but that didn't happen," said Peter Nordstrom, the study's lead.