Peripheral renin-angiotensin system and cognitive decline in Parkinson's disease patients without co-morbidities

Peripheral renin angiotensin system (RAS) regulates blood pressure and is involved in inflammation and oxidative stress processes. We aimed to determine whether a peripheral RAS may contribute to cognitive impairment in a highly selected group of Parkinson's disease (PD) patients without co-morbidities and concomitant medications affecting RAS. Correlations between RAS, blood pressure abnormalities and short-term blood pressure variabilities (BPV) were additionally assessed.

A total of 63 PD patients were enrolled. Clinical evaluation included assessment of motor abilities with dedicated scales. According to neuropsychological examination patients were classified into a group: with normal cognition (n = 20), mild cognitive impairment (MCI) (n = 23) or dementia (n = 20). All groups did not differ in terms of disease duration and dopaminergic treatment. Patients underwent 24h ambulatory blood pressure monitoring and orthostatic test. Plasma levels of renin, angiotensin II, aldosterone and plasma renin activity (PRA) were measured in a fasting state.

There were no differences in assessed parameters of RAS between all 3 groups. Better performance in visuospatial memory, visuospatial and executive functions was correlated to higher renin levels and PRA. Angiotensin II higher levels correlated with poor verbal memory and executive functions. Lower levels of renin and PRA resulted in increase of short-term BPV.

Peripheral RAS did not correlate with dementia or MCI, but may have an impact on selected cognitive domains and may contribute to an increase in BPV.