NEW YORK (Reuters Health) - Immediate relatives (brother, sister, mother, father, son or daughter) of patients with Parkinson's disease are at increased risk for developing depression and anxiety disorders, especially if the disease develops before the age of 75, according to a report in published Monday.

"This is the first study suggesting that relatives of patients with Parkinson's disease have an increased risk of anxiety and depression," study chief Dr. Walter Rocca, from the Mayo Clinic in Rochester, Minnesota, told Reuters Health.

Many patients with Parkinson's disease develop anxiety and depression after or even before they develop the disease. Rocca and colleagues explored whether this tendency was present to a greater extent in family members of people with Parkinson's disease compared with people without the disease.

"We found that, indeed, relatives of patients with Parkinson's disease are at increased risk for anxiety and depressive disorders, which suggests a genetic or other relationship between those disorders and Parkinson's disease," Rocca said.

The study involved 1,000 immediate relatives of 162 Parkinson's disease patients and 850 immediate relatives of 147 controls without Parkinson's disease.

Relatives of patients were 45 percent more likely to have a depressive disorder and 55 percent more likely to have an anxiety disorder, the report indicates. These associations remained even after adjusting for factors that might influence the results.

"The good news for relatives of patients with Parkinson's disease is that their risk of developing Parkinson's disease is relatively low; however, there is some increased risk of developing other conditions such as essential tremor, dementia, or anxiety and depression," Rocca said.

"We do not know whether the increased risk observed in this study is due to genetic factors. That is the simple explanation; however, family members share genes but also a lot of environmental factors such as diet and place of living. New studies are needed to answer these questions," Rocca noted.

SOURCE: Archives of General Psychiatry, December 2007.