Conference Coverage
VANCOUVER—Elevated systolic blood pressure predicts worsening motor function among patients with Parkinson’s disease, according to research presented at the 68th Annual Meeting of the American Academy of Neurology. Male gender and treatment with lower doses of dopaminergic medications also increase the risk of motor decline in these individuals, said Christina Lineback, a medical student at the University of Michigan in Ann Arbor.
Christina Lineback
Previous data have suggested that the presence and severity of comorbid brain pathologies may explain differences in disease progression between patients with Parkinson’s disease. In 2014, investigators at the University of Michigan found that cardiovascular risk factors such as hypertension, age, and diabetes influence the rate of motor disability accumulation in Parkinson’s disease.
Because high systolic blood pressure is a risk factor for the development of white matter hyperintensities, which in turn correlate with an increased rate of motor disability accumulation, Ms. Lineback and colleagues examined whether blood pressure predicted motor outcomes in patients with Parkinson’s disease. They performed a retrospective analysis of data from the CALM-PD trial, a two-year longitudinal study of 275 participants with Parkinson’s disease who were followed for 102 weeks. Each patient underwent several motor examinations using the Unified Parkinson’s Disease Rating Scale III (UPDRS III), as well as blood pressure measurements. The researchers examined mean systolic blood pressure using a multivariable linear-regression model that controlled for age, sex, disease duration, treatment arm, treatment dose, and open-label levodopa dose equivalence. Motor outcomes were determined by calculating the change in UPDRS III “on” scores from week 4 to week 102.
The study cohort of 275 patients with early Parkinson’s disease included 176 men and 99 women. Participants’ mean age was 60, and mean disease duration was 1.6 years. The overall mean systolic blood pressure was 130 mm Hg. Elevated mean systolic blood pressure was significantly associated with a greater decline in UPDRS III motor scores. In addition, male gender, randomization to pramipexole, and randomization to the lowest drug dose negatively affected motor performance.
Ms. Lineback offered several possible explanations for the association between elevated systolic blood pressure and worsening UPDRS III scores. High blood pressure may have a direct toxic effect on the brain that promotes the loss of neuronal integrity, she said. “Alternatively, elevated systolic blood pressure could serve as a trait marker for other unmeasured pathology … such as other cardiovascular risk factors.” In addition, the association may result from the autonomic dysfunction that is common in Parkinson’s disease. Lastly, the association could result from other unmeasured independent risk factors for motor decline, such as osteoarthritis or socioeconomic status.
One limitation of the study was the lack of information about other disease pathologies that could influence motor score, such as chronic conditions. In addition, the researchers did not account for the use of different classes of blood pressure medications.
“Identifying clinical features associated with more aggressive disease progression in Parkinson’s disease, such as blood pressure, may be important in future studies,” said Ms. Lineback. “Researchers may begin to incorporate these baseline prognostic markers into the randomization stage of future clinical trials.”
—Erik Greb