[Note: though the group of patients who did not become stooped had higher vitamin D levels than the ones who did, both groups would fall below the level the Vitamin D Council would consider "minimally acceptable" (about 40-50 ng/ml, the level at which the body stops putting D to work immediately and can store some).]
Objective: To determine the pathogenesis of the stooped posture in Parkinson disease (PD), we prospectively studied fractures in a cohort of patients with Parkinson disease for 5 years.
Design: At baseline, we recorded the dietary intake of vitamin D and serum concentrations of parathyroid hormone and 25-hydroxyvitamin D. [Vitamin D deficiency induces hyperparathyroidism, which contributes to reduced bone mineral density in Parkinson’s patients, as noted in a previous study.]
Bone mineral density and lateral thoracic and lumbar spine radiographs were obtained at baseline and every year for 5 yrs.
Results: During the 5-yr study period:
• Stooped posture developed in 34 patients;
• The rest of the 58 patients did not show stooped posture.
At baseline, mean serum 25-hydroxyvitamin D and parathyroid hormone levels were:
• 10.9 ng/ml and 73.1 pg/ml, respectively, in the stooped group,
• And 18.6 ng/ml and 56.4 pg/ml, respectively, in the nonstooped group.
Bone mineral density in the stooped group was significantly lower than in the nonstooped group.
Dietary intake of vitamin D in the stooped group was significantly lower than in the nonstooped group.
During the study period, 19 (22%) patients in the nonstooped group developed new vertebral fracture, compared with 23 (100%) patients in the stooped group.
The mean plus/minus SD percentage changes in bone mineral density were -6.5 plus/minus 0.6 in the stooped group and -3.8 plus/minus 0.8 in the nonstooped group.
Mean serum levels of 25-hydroxyvitamin D after 5 yrs were 7.0 ng/ml in the stooped group and 14.1 ng/ml in the nonstooped group.
Conclusions: Stooped posture in Parkinson disease may be caused by vertebral fractures resulting from vitamin D deficiency with compensatory hyperparathyroidism. Vitamin D supplementation may reduce stooped posture in patients with Parkinson disease.
Source: American Journal of Physical Medicine and Rehabilitation, Jan 5, 2011. PMID: 21273899, by Sato Y, Iwamoto J, Honda Y. Department of Neurology, Mitate Hospital, Tagawa; Institute for Integrated Sports Medicine, Keio University School of Medicine, Tokyo, Japan.