Vitamin D3 supplementation may stabilize PD for a short period in patients with FokI TT or CT genotypes without triggering hypercalcemia, although this effect may be nonspecific for PD. This trial was registered at UMIN Clinical Trials Registry as UMIN000001841.
We aimed to examine associations among serum 25-hydroxyvitamin D levels, 1,25-dihyroxyvitamin D levels, vitamin D receptor polymorphisms, vitamin D binding protein gene polymorphisms, and the severity of Parkinson's disease. In 137 patients, the severity of Parkinson's disease was evaluated using Hoehn & Yahr stage and Unified Parkinson's Disease Rating Stage by neurologists and compared with 25-hydroxyvitamin D, 1,25-hydroxyvitamin D, vitamin D receptor polymorphisms, ie, FokI (rs10735810), BsmI (rs1544410), Cdx2 (rs11568820), ApaI (rs7976091), and TaqI (rs731236), and vitamin D binding protein gene polymorphisms GC1 (rs7041)/GC2 (rs4588) in a cross-sectional study. Mean ± standard deviation levels of 25-hydroxyvitamin D were 21.1 ± 9.0 ng/mL. Levels were deficient (<20 ng/mL) in 49% of patients. In contrast, 1,25-hydroxyvitamin D levels were considered normal in all patients. Higher circulating 25-hydroxyvitamin D levels were significantly associated with milder Parkinson's disease evaluated by Hoehn & Yahr stage (P = .002) and total Unified Parkinson's Disease Rating Stage (P = .004) even after multivariate adjustment for 8 covariates, including disease duration. However, significant associations were not observed in 1,25-hydroxyvitamin D levels. Under multivariate analysis with 25-hydroxyvitamin D as well as other 8 covariates including disease duration, carriers of vitamin D receptor FokICC genotype had a milder form of Parkinson's disease: odds ratio, 0.32; 95% confidence interval, 0.16 to 0.66, P = 0.002. These results suggest that higher 25-hydroxyvitamin D levels and the vitamin D receptor FokICC genotype may be independently associated with milder forms of Parkinson's disease. However, significant associations were not observed in 1,25-hydroxyvitamin D levels.
Clinical symptoms of Parkinson's disease (PD) include not only motor distress but also autonomic dysfunction. Orthostatic hypotension (OH) occurs in one-fifth to one-half of all patients with PD. We examined the relation of this type of hypotension to clinical features and cardiovascular parameters such as cardiac 123I-meta-iodobenzylguanidine (MIBG) uptake, changes on the Valsalva maneuver, and plasma norepinephrine concentrations on head-up tilt-table testing (HUT). We performed HUT in 55 patients with PD and divided them into two groups according to the presence or absence of OH, defined as a drop in systolic blood pressure (SBP mmHg) by 20 mmHg or more on standing. We evaluated cardiac sympathetic function by 123I-MIBG scintigraphy and assessed cardiovascular autonomic function by using the Valsalva maneuver in all subjects. We also performed HUT, 123I-MIBG scintigraphy and assessed cardiovascular autonomic function by using the Valsalva maneuver in 20 controls. The results of HUT showed that 20 patients had OH and 35 did not. The hypotension was associated with gender, older age, longer disease duration, posture and gait instability phenotype, low mini-mental state examination scores and visual hallucinations. Cardiac 123I-MIBG uptakes were lower in patients with OH. SBP fell further during early second phase in patients with OH than in patients without the condition and their increase in SBP during the late second phase and the overshoot of SBP during the fourth phase were lower. The blood pressure recovery time during the fourth phase on the Valsalva maneuver was longer in patients with OH than in those without OH. There was, however, no association between the fall in SBP on HUT and baroreflex sensitivity or the plasma norepinephrine concentrations, adjusted by age, disease duration, disease severity and dopaminergic medication using multiple regression analyses. Patients without OH already had impaired cardiac sympathetic and baroreceptor reflex functions as early abnormalities of cardiovascular autonomic control. Our results suggest that pronounced vasomotor and cardiac sympathetic dysfunction is the primary cause of OH in PD, although baroreceptor reflex failure may also make a minor contribution. It was unclear whether vasomotor and cardiac sympathetic dysfunction in patients with PD was caused primarily by the impairment of preganglionic or postganglionic lesions.
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