The influence of vascular risk factors on cognitive function in early Parkinson's disease

Abstract

Objectives: Hypertension, dyslipidemia, diabetes, and obesity are well-established risk factors for cognitive impairment and dementia in older adults. In contrast, previous studies that have assessed the impact of vascular risk factors (VRFs) on cognition in Parkinson's disease (PD) have had methodological limitations and reported conflicting findings. We address this question in a large well-characterized cohort of de novo PD patients.

Methods: A total of 367 untreated and non-demented patients aged 50 years and older with early PD (H&Y = 1.0-2.0) underwent a comprehensive clinical and neuropsychological assessment at baseline and 24 months later. A series of linear mixed models were used to determine the effects of VRFs on cognition while controlling for patient and disease characteristics. The outcomes included norm-referenced Z-scores of global cognition, visuospatial skills, verbal episodic memory, semantic verbal fluency, attention, and working memory tests.

Results: A longer history of hypertension and a higher pulse pressure were significant predictors of lower Z-scores on immediate and delayed free recall, recognition, and verbal fluency tests. On average, every 10 mmHg increase in pulse pressure was associated with a 0.08 reduction on the cognitive Z-scores. The effects were independent of age, education, disease duration, motor impairment, medication, and depressive symptoms. Other VRFs were not associated with cognitive outcomes.

Conclusions: Our results are consistent with previous studies suggesting that hypertension exerts a detrimental effect on memory and verbal fluency in early PD. Management of blood pressure and cardiovascular health may be important to reduce risk of cognitive decline in PD. Copyright © 2017 John Wiley & Sons, Ltd.

Keywords: Parkinson; cognition; dementia; hypertension; metabolic syndrome; pulse pressure; vascular risk factors.