In this Finnish prospective cohort vitamin D status was inversely associated with Parkinson's disease

1. www.pronutritionist.net
Serum Vitamin D and the Risk of
Parkinson Disease
Knekt P et al.
Arch Neurol 2010; 67: 808-811.
Page 1 Knekt P. et al. Arch Neurol 2010; 67: 808-811.

2. Page 2
Background (1/2)
• Parkinson disease is a major cause of disability in elderly
individuals
• Its risk factors are relatively unknown
• Vitamin D plays an important role in the pathogenesis of skeletal
disorders and calcium homeostasis
• Vitamin D inadequacy also predicts increased risk of other
chronic conditions as
– cancer
– cardiovascular diseases
– type 2 diabetes
• Higher 25-hydroxyvitamin D level is also associated with lower
relapse risk in multiple sclerosis
• Vitamin D deficiency might be also associated with
neurodevelopmental disordersas autism and schizophrenia
Knekt P. et al. Arch Neurol 2010; 67: 808-811. www.pronutritionist.net

3. Background (2/2)
• Recently chronically inadequate vitamin D intake was
proposed to play a significant role in the pathogenesis
of Parkinson disease
– Possible mechanism might be a continuously inadequate vitamin
D status leading to a chronic loss of dopaminergic neurons in the
brain
• The exact mechanisms by which vitamin D may protect
against Parkinson disease are not fully understood
• The epidemiological evidence of an association
between vitamin D and Parkinson disease is limited to
cross-sectional studies
– showing lower vitamin D status in patients with Parkinson disease
compared with healthy controls
www.pronutritionist.netKnekt P. et al. Arch Neurol 2010; 67: 808-811.3

4. Methods
• Prospective follow-up study (The Mini-Finland
Health Survey)
• Follow-up 29 years
• n = 3173, aged 50 to 79 years
• Serum 25-hydroxyvitamin D level was
determined from frozen samples stored at
baseline
• Estimates of the relationship between serum
vitamin D concentration and Parkinson
disease incidence were calculated using the
Cox model
Page 4 Knekt P. et al. Arch Neurol 2010; 67: 808-811. www.pronutritionist.net

5. Results (1/2)
• At baseline, Parkinson disease cases more often were
– nonsmokers
– did not have hypertension or diabetes
than subjects who were free of the disease
• Serum vitamin D concentration was lower among Parkinson
disease cases
• A significant inverse association between sex- and
ageadjusted serum vitamin D level and Parkinson disease
incidence was found
Page 5 Knekt P. et al. Arch Neurol 2010; 67: 808-811. www.pronutritionist.net

6. Results (2/2)
• Individuals with a serum vitamin D concentration
of at least 50 nmol/L had a 65% lower risk than
those with values less than 25 nmol/L
• Mean serum vitamin D level in the present
population was about 50% of the suggested
optimal level (75-80 nmol/L)
• Despite the overall low vitamin D levels in the
study population, a dose-response relationship
was also found.
www.pronutritionist.netKnekt P. et al. Arch Neurol 2010; 67: 808-811.6

7. Discussion
• This cohort study shows that low serum vitamin D
level predicts an elevated risk of Parkinson
disease incidence
• Only a single measurement of serum 25
hydroxyvitamin D was available, which fails to take
into account the intraindividual seasonal variation
– However no interaction between serum vitamin D
concentration and season was observed
• Because of the small number of cases and the
possibility of residual confounding, large cohort
studies are needed
• In addition, more studies from association of
vitamin D and neurological disordersis needed
Page 7 Knekt P. et al. Arch Neurol 2010; 67: 808-811. www.pronutritionist.net