Parkinson's May Cause Decline Even Before Onset

Declines in physical, mental and emotional health and intensifying pain may begin several years before the onset of Parkinson’s disease and continue thereafter, according to results from the Nurses’ Health Study and Health Professionals Follow Up Study.

"We observed a decline in physical function in PD patients relative to their healthy counterparts beginning three years prior to diagnosis in men and 7 years prior to diagnosis in women," Natalia Palacios, PhD, the study’s lead investigator and a member of the Department of Nutrition at the Harvard School of Public Health, said in a news release.

"The decline continues at a rate that is five to seven times faster than the average yearly decline caused by normal aging in individuals without the disease."

The study included 121,701 female RNs enrolled in the Nurses’ Health Study and 51,350 male health professionals enrolled in the Health Professionals Follow Up Study. In both ongoing studies, participants fill out biannual questionnaires about a variety of lifestyle characteristics and document the occurrence of major chronic disease. 

In the NHS study, questionnaires measured health-related quality of life in eight areas: physical functioning, role limitations due to physical problems, role limitations due to emotional problems, vitality, bodily pain, social functioning, mental health and general health perceptions. In the HPFS, only physical functioning was assessed.

Researchers identified 454 men and 414 women with PD in the two cohorts. At 7.5 years prior to diagnosis, physical function among PD cases, in both men and women, was comparable to that in the overall cohort. A decline began approximately three years prior to diagnosis in men and approximately 7.5 years prior to diagnosis in women. Physical function continued to decline thereafter at a rate of 1.43 and 2.35 points per year — on a point scale of 1 to 100 — in men and women, respectively. 

In comparison, the average yearly decline in physical function among individuals without PD was 0.23 in men and 0.42 in women. Other measures of quality of life, available only in the nurses study, declined in a similar pattern.

Palacios noted that a strength of the study is the availability of prospective data on both PD patients and a healthy comparison group, and the ability to chart the deterioration in functioning and QOL over the whole study follow-up, which included many years prior to diagnosis.

"This result provides support to the notion that the pathological process leading to PD may start several years before PD diagnosis," Palacios said. "Our hope is that, with future research, biological markers of the disease process may be recognizable in this preclinical phase."

(Source: TodayinOT.com)