Presence of dementia is associated with a higher death rate among people with Parkinson’s Disease, according to a study published in the January issue the Archives of Neurology.

The cohort study of 138,000 Medicare beneficiaries nationwide with incident of Parkinson’s disease from 2002 and 2008 found diagnosed dementia affected close to 70 percent of the study’s population by the end of the study period. During that time 64 percent of patients died.

Parkinson’s disease patients with dementia had greater risk of death than those without dementia.

According to Allison W. Willis, M.D., and colleagues from Washington University School of Medicine, St. Louis., the highest frequency of dementia was found in black patients (78.2 percent), followed by Hispanics (73.1 percent). White and Asian patients with Parkinson’s had similar rates of dementia at around 69 percent.

"We demonstrate that dementia occurs commonly in patients with incident PD 65 years and older; this had the strongest effect on age-adjusted survival among the variables that we studied," said the authors.

"Our data highlight the need for prevention of or treatment for dementia in patients with PD because of its effect on survival," concluded the authors.