Parkinson's disease (PD) could commence with a number of non-motor symptoms that occur several years before diagnosis, a growing body of research indicates.
A report, outlined in the Journal of Parkinson's Disease, found people suffering from the ailment report declines in their emotional, mental and physical health several years before PD makes an appearance and with these losses continuing as the disease takes hold.
If this is proven to be correct, it could eventually enable people to receive diagnostic tests through expatriate medical insurance policies that could identify them as at-risk of suffering from PD, enabling them to receive preventative care and prepare themselves for the condition in the future.
The study, which was led by Dr Natalia Palacios of Harvard School of Public Health's Department of Nutrition, involved analysing 121,701 female and 51,350 male nurses enrolled in either the Health Professionals Follow Up Study or the Nurses' Health Study, wherein they filled out questionnaires twice a year asking about a variety of characteristics and documenting any chronic illnesses that became apparent.
A total of 454 men and 414 women who eventually suffered from PD were identified within the two demographics.
While these individuals had comparable physical function to their peers eight years before their diagnoses, females who would eventually suffer from PD began reporting declines 7.5 years before they were told they had the condition, while this was three years for males.
"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," Dr Palacios said.
"Our hope is that, with future research, biological markers of the disease process may be recognisable in this preclinical phase," she added.
According to the US' National Institute of Neurological Disorders and Stroke, PD typically begins to impact people from around the age of 60, with its incidence increasing as the populace ages.
Although there are no cures for the condition as of yet, a drug called levodopa has been identified as a way to reduce symptoms, while brain surgery has also been effective in certain instances.