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1 of 2 | On top of living with Parkinson’s disease, receiving a diagnosis of dementia can be especially traumatic for patients and their families, Photo by PicsbyAnnyk/
PixabayNEW YORK, Aug. 7 (UPI) -- People with Parkinson's disease fear developing dementia, but their risk may be less than once believed, or it could strike later than expected in the movement disorder's course, a new study has found. The study, conducted at the University of Pennsylvania in Philadelphia, was published Wednesday in the online issue of Neurology, the medical journal of the American Academy of Neurology.
Researchers undertook the study because "we thought that the most-cited research to date reporting on dementia risk in Parkinson's was potentially flawed," said the study's corresponding author, Dr. Daniel Weintraub, a professor of psychiatry in the Perelman School of Medicine at the University of Pennsylvania.
On top of living with Parkinson's disease, receiving a diagnosis of dementia can be especially traumatic for patients and their families, Weintraub said.
This study offers hope, with more optimistic projections of the long-term dementia risk for people with Parkinson's disease. That means a longer time frame to prevent or slow down the onset of cognitive decline in dementia could exist.
It is commonly reported that dementia occurs in up to 80% of patients with Parkinson disease, but this information came from studies published more than two decades ago, included relatively small numbers of participants and harbored other limitations, researchers noted.
"This study is more rigorous in multiple ways," Weintraub said, as it incorporates data from two large, ongoing, observational studies. It's encouraging, he said, that "dementia in Parkinson's disease is not universal" and arises later than previously perceived.
In one of those studies -- an international investigation called the Parkinson's Progression Markers Initiative -- 417 participants (65% male) with an average age of 62 had received a new diagnosis of Parkinson's disease and had not yet undergone treatment at the time of entry.
The other study -- at the University of Pennsylvania -- included 389 people with Parkinson's who averaged 69 years in age. They were diagnosed an average of six years before the study began, and researchers monitored for possible development of dementia.
In the international study, researchers estimated a 9% probability of a dementia diagnosis 10 years after Parkinson's disease was diagnosed.
However, in the Pennsylvania study, researchers estimated a 27% probability of participants being diagnosed with dementia 10 years following a Parkinson's diagnosis. The estimated risk of dementia was 50% 15 years after a Parkinson's diagnosis and 74% 20 years after diagnosis.
Factors that raised the risk of dementia in the Pennsylvania study included older age at the time of Parkinson's diagnosis, male sex and a lower level of education, researchers said.
They also acknowledged a limitation of both studies -- that participants were highly educated and primarily White people recruited for research purposes, so they may differ from the general population.
"Screening for cognitive abilities in Parkinson's disease should start at the time of diagnosis and should occur annually," Weintraub said. In addition, "There remains a great need to develop options for treating or preventing Parkinson's-related cognitive impairment."
The Michael J. Fox Foundation for Parkinson's Research and numerous funding partners supported the international study. The National Institute on Aging funded the University of Pennsylvania portion.
"This is an impressive study of dementia in Parkinson's disease. Most people think of Parkinson's disease as a motor disorder, but it can have cognitive symptoms, as well," said Dr. Nandakumar Narayanan, a professor of neurology at University of Iowa Health Care in Iowa City. He was not involved in the study.
"Dementia and these cognitive symptoms continue to be an important problem in Parkinson's disease, and healthcare providers should be aware of them," Narayanan said.
However, he noted that there are "wide margins of errors" in this study's estimates, so more information would be necessary to gauge and reduce any particular patient's specific risk.
"Dementia is one of the most dreaded non-motor manifestations of Parkinson's disease -- and justifiably so, since it is an important contributor to disability, poor quality of life, caregiver burnout and death," said Dr. Guy Schwartz, co-director of the Stony Brook Parkinson's and Movement Disorders Center at Stony Brook Medicine on Long Island, N.Y.
Yet, effective treatments for dementia associated with Parkinson's disease are lacking, unlike treatments for its motor symptoms, Schwartz noted.
Meanwhile, patients "are often times preoccupied" with the prospective "loss of independence, compromised ability to communicate, inability to enjoy hobbies and fear of nursing home institutionalization," among other possible upcoming challenges, he said.
The study also found dementia is more common in men than women, Schwartz pointed out, raising the question of whether hormonal factors can give rise to this loss of cognitive functioning.
Dr. Michael Okun, national medical adviser to the Parkinson's Foundation, stressed the importance of being "extremely cautious in the interpretation of studies examining long-term dementia risk in Parkinson's disease."
"Though we would welcome news of declining rates of dementia in Parkinson's, we should be careful about drawing conclusions prematurely," said Okun, who also is director of the Norman Fixel Institute for Neurological Diseases at the University of Florida Health in Gainesville.
"Who we recruit for studies, and what criteria we use to define dementia, can significantly skew results in one direction or another."