The study, “Fatigue in Parkinson’s Disease Associates with Lower Ambulatory Diastolic Blood Pressure,” was published in the Journal of Parkinson’s Disease.
Lack of energy (fatigue) is one of the most common — and most disabling — symptoms among people with Parkinson’s, and has a significant impact on patients’ quality of life. However, the biological mechanisms underlying fatigue are poorly understood.
Low blood pressure, also known as hypotension, and overall blood pressure variability are common in Parkinson’s disease (PD). But scientists still have not fully connected such physiological changes with other non-motor symptoms of this neurodegenerative disorder.
Researchers at the University of Michigan now sought to investigate the differences in 24-hour blood pressure measurements in Parkinson’s patients with and without fatigue.
A total 35 participants had their diastolic and systolic blood pressure monitored hourly for a day in their home environment. Systolic blood pressure, or SBP, which is the top number presented on a blood pressure monitor, measures the pressure in the blood vessels when the heart beats. Diastolic blood pressure, or DBP, the second number presented, measures blood vessel pressure when the heart rests between beats. The researchers said DBP may better reflect the type of autonomic dysfunction that is common in Parkinson’s.
Fatigue was assessed using the Movement Disorders Society Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) part I. Based on their test results, participants were considered either fatigued — 11 subjects; mean age of 71.2 years — or non-fatigued — 24 subjects; mean age of 68.4 years. Fatigued patients had a lower mean diastolic blood pressure than those without fatigue (67.8±4.8 vs. 75.6±9.4 mmHg). These differences were more prominent in the morning.
“It is possible that fatigue symptoms themselves do not wax and wane throughout the day with hypotension but rather are a correlate of a tendency towards low vascular tone in general,” the researchers said.
No differences were found in the participants’ autonomic symptoms or on an office-based diastolic and systolic blood pressure assessment performed on the day of 24-hour monitor initiation.
“This is a novel finding that we hope may open the door for new, currently untapped ways to treat fatigue symptoms in PD,” Vikas Kotagal, MD, MS, of the department of neurology at the University of Michigan and Veterans Affairs Ann Arbor Health System (VAAAHS) and Geriatric Research Education and Clinical Center (GRECC), said in a press release.
“We hope these results will help move us towards better treatments for PD fatigue,” added Kotagal, the study’s first author. “If we can design and test treatments that increase DBP [diastolic blood pressure] without worsening the harmful cardiovascular effects of high systolic blood pressure (SBP), we may be able improve fatigue symptoms in PD. Our data may also have implications on the off-target side effects of some classes of antihypertensive medications when used by patients with PD and fatigue.”