Funding ended and enrollment not completed within a certain time period

Based on Parkinson's disease (PD)/vitamin B12 deficiency symptom overlap and PD patients' propensity to avoid protein (the dietary source of vitamin B12), this study proposes to prospectively investigate the vitamin B12 status of PD patients over time. In addition, this study will provide critical pilot data evaluating the efficacy of treating those patients considered to have below-normal vitamin B12 levels in serum. Further, it will also explore the concept that supplementing PD patients having "low-normal" vitamin B12 levels with vitamin B12 improves either the non-motor PD symptoms or homocysteine levels in PD patients receiving levodopa.

Study Hypotheses:

1. Serum cobalamin (B12) concentrations in patients with Parkinson's disease (PD) are significantly lower than B12 concentrations in a) cohabiting spousal caregiver controls; and b) population-based, age-matched controls.
2. Supplementation with B12 in levodopa-treated PD patients with low (<200 pg/ml) or low-normal (200-300 pg/ml) serum B12 levels is associated with significant improvement in their non-motor symptoms and reduces total plasma homocysteine concentration [Hcy], a known biomarker for risk of dementia and cerebrovascular disease.

Inclusion Criteria:

• Patients seen in Emory Healthcare System at least once between 1/1/2002 and 05/31/2006 with idiopathic Parkinson's disease (defined as):

• >2 of cardinal signs/symptoms of Parkinson's disease (bradykinesia, tremor, rigidity)

• >50% improvement of symptoms when dopaminergic therapy started

• Cohabiting spousal caregivers (without Parkinson's disease) of patients enrolled in study are also eligible (but not required) to participate

  • Coexisting depression, if present, is stable
  • Normal thyroid screen (done at Screening Visit or at Emory Healthcare System within 3 months of Screening Visit)
  • Males must have normal fasting testosterone levels (done at Screening visit or within 6 months of Screening Visit)

Exclusion Criteria:

• Unstable medical conditions (terminal cancer, angina, etc) which could interfere with study assessments or put patient at risk for not completing the assessments.
• Dopaminergic-unresponsive parkinsonism (i.e., patient has suspected multiple systems atrophy (MSA), vascular or another form of parkinsonism)
• Prior history of vitamin B12 deficiency or taking vitamin B12 supplements or injections (single multivitamin supplements are not an exclusion criteria)
• Untreated testosterone or thyroid abnormality