Washington, Oct 9 : A new study has found that relatives of people living with Parkinson's disease may be at an increased risk of developing dementia or cognitive impairment.

Parkinson’s disease is characterized by a decline in the functions of the central nervous system, such as motor skills and speech. Several studies have shown an increased risk of dementia in first-degree relatives of Parkinson’s disease patients, while other studies have not confirmed the association.

“The co-occurrence of Alzheimer’s disease and Parkinson’s disease in families and in individuals may be due to the sharing of susceptibility genetic variants,” the authors write.

For the study, Walter A. Rocca, M.D., M.P.H, of the Mayo Clinic College of Medicine, Rochester, Minn., and colleagues studied 1019 first-degree relatives of 162 Parkinson's disease patients and 858 relatives of 147 similar subjects without the disease.

The team measured levels of thinking ability by performing either telephone interviews or by interviewing close associates of Parkinsons patients.

The results showed that relatives of Parkinsons disease patients were 37 percent more likely to show thinking deficits or dementia than were relatives of unaffected study participants. Furthermore the risk increased if the Parkinsons patient developed their condition before turning 66 years of age.

According to the authors, the study proves that there is a partial link between Parkinsons disease and dementia.

“This study provides evidence that relatives of patients with Parkinson’s disease have an increased risk of cognitive impairment or dementia. This association is primarily driven by families of patients with younger age at onset of Parkinson’s disease, but the risk does not vary across relatives of patients with different clinical characteristics of Parkinson’s disease,” the authors write.

“The observed associations suggest the action of shared familial susceptibility factors, genetic or nongenetic,” they add.

The study is published in the October issue of Archives of Neurology, one of the JAMA/Archives journals. (ANI)