Bone mineral density and serum vitamin D status in Parkinson's disease: Are the stage and clinical features of the disease important?

No Vitamin D Deficiency in Patients with Parkinson’s Disease

Previous trials describe a decrease of vitamin D levels in patients with Parkinson’s disease and relationships to clinical disease severity. This case control study found higher but not significant 25-OH-vitamin D plasma levels in patients with Parkinson’s disease compared with age- and sex-matched controls and no associations to clinical parameters, such as rating scores of disease severity or assessments of cognitive function. A certain variability of vitamin D concentrations was observed in both cohorts, which were investigated during the same season. These outcomes put into perspective the emerging discussion on the importance of vitamin D in Parkinson’s disease. Our results warrant further confirmatory research with a strict matching design of patients and controls, which has not been done in previous investigations. We stress that this case control study does not allow any comment on the putative beneficial effects of vitamin D supplementation, ie, on bone mass or bone mineral density, in patients with Parkinson’s disease.

Parkinson’s Disease Etiology: Insights and Associations with Phosphate Toxicity

The present paper investigated the association of Parkinson’s disease etiology with phosphate toxicity, a pathophysiological condition in which dysregulated phosphate metabolism causes excessive inorganic phosphate sequestration in body tissue that damages organ systems. Excessive phosphate is proposed to reduce Complex I function of the mitochondrial electron transport chain in Parkinson’s disease and is linked to opening of the mitochondrial permeability transition pore, resulting in increased reactive oxygen species, inflammation, DNA damage, mitochondrial membrane depolarization, and ATP depletion causing cell death. Parkinson’s disease is associated with α-synuclein and Lewy body dementia, a secondary tauopathy related to hyperphosphorylation of tau protein, and tauopathy is among several pathophysiological pathways shared between Parkinson’s disease and diabetes. Excessive phosphate is also associated with ectopic calcification, bone mineral disorders, and low levels of serum vitamin D in patients with Parkinson’s disease. Sarcopenia and cancer in Parkinson’s disease patients are also associated with phosphate toxicity. Additionally, Parkinson’s disease benefits are related to low dietary phosphate intake. More studies are needed to investigate the potential mediating role of phosphate toxicity in the etiology of Parkinson’s disease.

Bone Mineral Density Loss in Parkinson's Disease: Impact of Clinical Subtypes

Background: This study aimed to compare the BMD status among the clinical subtypes of PD and healthy controls.Methods: Sixty patients with PD and 30 healthy age- and sex-matched controls were included in this study. The patients were divided into postural instability gait difficulty-dominant type (PIGDDT) group and tremor-dominant type (TDT) group based on the Unified Parkinson's Disease Rating Scale (UPDRS) score. BMD was measured using dual-energy X-ray absorptiometry scans in femoral and lumbar regions.Results: The T-scores in femoral and lumbar regions were similar in all groups. The prevalence of osteopenia was higher than the prevalence of osteoporosis in all three groups for femoral regions. The prevalence of osteoporosis in the intertrochanteric region and total femur in the PIGDDT group was higher than in the TDT group and controls. Our data showed a trend toward higher prevalence of osteoporosis in the PIGDDT group.Conclusion: The prevalence of osteopenia and osteoporosis may differ between clinical subtypes of PD and healthy controls. Osteopenia is more common than osteoporosis for all groups. The patients with PIGDDT of PD tended to have higher prevalence of osteoporosis, even at early stages of disease, compared to those with TDT and healthy controls.

Effects of Neurological Disorders on Bone Health

Neurological diseases, particularly in the context of aging, have serious impacts on quality of life and can negatively affect bone health. The brain-bone axis is critically important for skeletal metabolism, sensory innervation, and endocrine cross-talk between these organs. This review discusses current evidence for the cellular and molecular mechanisms by which various neurological disease categories, including autoimmune, developmental, dementia-related, movement, neuromuscular, stroke, trauma, and psychological, impart changes in bone homeostasis and mass, as well as fracture risk. Likewise, how bone may affect neurological function is discussed. Gaining a better understanding of brain-bone interactions, particularly in patients with underlying neurological disorders, may lead to development of novel therapies and discovery of shared risk factors, as well as highlight the need for broad, whole-health clinical approaches toward treatment.