Intervening Effects of Orthostatic Blood Pressure Change on Subcortical Atrophy and Cognition in De Novo and Drug-Naïve Parkinson’s Disease

A systematic review and meta-analysis on the association between orthostatic hypotension and mild cognitive impairment and dementia in Parkinson's disease

BACKGROUND

Cognitive impairment is a frequent disabling feature of Parkinson's disease (PD). Orthostatic hypotension (OH) is treatable and may be a risk factor for cognitive impairment.

OBJECTIVE

We conducted a systematic review and meta-analysis to examine the relationship between OH with PD-associated minimal cognitive impairment (PD-MCI) and dementia (PDD) and assess the mitigating effects of potential confounding factors.

METHODS

Observational studies published in English, Spanish, French, or Portuguese up to January 2022 were searched for in PubMed, EBSCO, and SciELO databases. The primary aim of this study was to revise the association between OH with PD-MCI and PDD. Alongside, we assessed OH as related to cognitive rating scales. Fixed and random models were fitted. Meta-regression was used to assess the mitigating effects of confounding variables.

RESULTS

We identified 18 studies that reported OH association with PDD or PD-MCI, 15 of them reporting OH association with cognitive rating scales. OH was significantly associated with PDD/PD-MCI (OR, 95% CI: 3.31, 2.16-5.08; k = 18, n = 2251; p < 0.01). OH association with PDD (4.64, 2.68-8.02; k = 13, n = 1194; p < 0.01) was stronger than with PD-MCI (1.82, 0.92-3.58; k = 5, n = 1056; p = NS). The association between OH and PD-MCI/PDD was stronger in studies with a higher proportion of women and in those with a lower frequency of supine hypertension. Global cognition rating scale scores were lower in patients with OH (SMD, 95% CI: - 0.55, - 0.83/ - 0.26; k = 12, n = 1427; p < 0.01).

CONCLUSIONS

Orthostatic hypotension shows as a significant risk factor for cognitive impairment in PD, especially in women and patients not suffering from hypertension.

Caudate-anchored cognitive connectivity pursuant to orthostatic hypotension in early Parkinson's disease

¹⁸F-Florbetaben is a tracer used to evaluate the metabolic activity of and amyloid accumulation in the brain when measured in early- and late-phase, respectively. The metabolism of neural substrates could be viewed as a network and might be an important factor in cognition. Orthostatic hypotension (OH) might play an indirect moderating role in cognition, and its latent influence could modify the inherent cognitive network. This study aimed to identify changes of cognitive connectivity according to orthostatic stress in patients with early Parkinson's disease (PD). This study included 104 early PD patients who were evaluated with a head-up tilt-test and¹⁸F-Florbetaben positron emission tomography (PET). Cognition was assessed with a comprehensive neuropsychological battery that gauged attention/working memory, language, visuospatial, memory, and executive functions. PET images were analyzed visually for amyloid deposits, and early-phase images were normalized to obtain standardized uptake ratios (SUVRs) of pre-specified subregions relevant to specific cognitive domains. The caudate nucleus was referenced and paired to these pre-specified regions. The correlations between SUVRs of these regions were assessed and stratified according to presence of orthostatic hypotension. Among the patients studied, 22 (21.2%) participants had orthostatic hypotension. Nineteen patients (18.3%) were positive for amyloid-β accumulation upon visual analysis. Moderate correlations between the caudate and pre-specified subregions were observed (Spearman's rho, range [0.331-0.545]). Cognition did not differ, but the patterns of correlation were altered when the disease was stratified by presence of orthostatic stress. In conclusion, cognition in early PD responds to hemodynamic stress by adapting its neural connections between regions relevant to cognitive functions.

Delayed orthostatic hypotension in Parkinson's disease

Orthostatic hypotension (OH) is relatively common in the early stage of Parkinson's disease (PD). It is divided into delayed OH and classical OH. Classical OH in PD has been investigated widely, however, the clinical implications of delayed OH in PD have seldom been studied. The purpose of this study is to characterize delayed OH in PD. A total of 285 patients with early drug-naïve PD were enrolled and divided into three groups according to orthostatic change: no-OH, delayed OH, and classical OH. The disease severity in terms of motor, non-motor, and cognitive functions was assessed. The cortical thickness of 82 patients was analyzed with brain magnetic resonance imaging. The differences among groups and linear tendency in the order of no-OH, delayed OH, and classical OH were investigated. Seventy-seven patients were re-evaluated. Initial and follow-up evaluations were explored to discern any temporal effects of orthostasis on disease severity. Sixty-four (22.5%) patients were defined as having delayed OH and 117 (41.1%) had classical OH. Between-group comparisons revealed that classical OH had the worst outcomes in motor, non-motor, cognitive, and cortical thickness, compared to the other groups. No-OH and delayed OH did not differ significantly. Linear trends across the pre-ordered OH subtypes found that clinical parameters worsened along with the orthostatic challenge. Clinical scales deteriorated and the linear gradient was maintained during the follow-up period. This study suggests that delayed OH is a mild form of classical OH in PD. PD with delayed OH has milder disease severity and progression.

Blood pressure lability is associated with subcortical atrophy in early Parkinson's disease

OBJECTIVE

Increased cerebral white matter intensities associated with blood pressure (BP) lability were reported in patients with Parkinson's disease. However, this type of cardiovascular dysautonomia has seldom been associated with disruptions in deep gray matter structures in Parkinson's disease. In the present study, the associations between BP lability and subcortical deep gray matter structures in early Parkinson's disease were evaluated.

METHODS

The present study included 98 early nondemented Parkinson's disease patients. Supine and orthostatic BPs were measured using head-up tilt tests. BP variabilities, measured as standard deviations of 24-h daytime and nighttime BPs, were assessed using 24-h ambulatory BP monitoring. Every patient underwent brain MRI and measurement of deep gray matter volumes. The associations between BP lability and deep gray matter structures were analyzed.

RESULTS

Parkinson's disease patients with orthostatic hypotension had smaller volumes of striatum, particularly caudate, than patients without OH after adjusting for covariates of age, sex, disease duration, and Mini-Mental Status Examination score. Nocturnal BP variability was inversely associated with thalamus, hippocampus, and globus pallidus volumes.

CONCLUSION

The results from the present study showed that BP lability was adversely associated with structural changes in early Parkinson's disease. Different forms of BP fluctuations influenced distinct deep gray matter structures.