Disorders of the nervous system account for more long-term care, chronic suffering, and diminished quality of life than all other disorders combined. Age-related neurodegenerative disorders are chronic and progressive conditions that result from loss of the maintenance of neurons involved in cognitive, emotional, motor and sensory functions. The two most common age-related neurodegenerative disorders are Alzheimer's (AD) and Parkinson's diseases (PD). This report investigates the possible relationships both of B vitamin status and supplementation and of berry consumption with age-related neurodegenerative disorders. Key Questions include: B Vitamins: 1. What is the evidence regarding mechanisms of action of the B vitamins B1, B2, B6, B12, and folate (singly and in combination) for preventing, decreasing the rate of progression of, or reversing the neurological changes associated with age-related neurodegenerative conditions such as Parkinson's or Alzheimer's disease? 2. What is the evidence that the B vitamins B1, B2, B6, B12, and folate can prevent, decrease the rate of progression of, or reverse the neurological changes associated with age-related neurodegenerative conditions such as Parkinson's or Alzheimer's disease in humans 3. What adverse events in humans have been reported in the literature for supplementation with the B vitamins B1, B2, B6, B12, and folate? a. Do the frequency of adverse events vary with source, dose, or other evaluated factors? Berries: 1. What are the constituents in berries with beneficial nerve- and brain-related health effects (from in vitro, animal, and human studies)? a. In what other food sources are these constituents found? 2. What is the evidence regarding mechanisms of action of berry constituents for preventing, decreasing the rate of progression of, or reversing the neurological changes associated with age-related neurodegenerative conditions, including Parkinson's or Alzheimer's disease? 3. What is the evidence that the constituents of berries can prevent, decrease the rate of progression of, or reverse the neurological changes associated with age-related neurodegenerative conditions, including Parkinson's or Alzheimer's disease in humans a. Is the source, species, dose, composition, characteristics, or processing of berries and berry constituents related to the effect of the intervention? 4. What adverse events in humans have been reported in the literature for the constituents in berries? a. Do the frequency of adverse events vary with source, dose, or other evaluated factors? We reviewed all studies of berries and their constituents that addressed these questions, regardless of specific topic. However, for B vitamins we restricted the specific topics to the following: B Vitamins: Human Studies: Association between B vitamin treatment/intake with diagnosis or severity of AD or PD, cognitive function, or histopathology; Association of B vitamin status and AD or PD diagnosis, histopathology, severity of disease, or cognitive function; B Vitamins: Animal / In Vitro Studies: Effect of B vitamin supplementation or deficiency on cognitive function, movement disorders, histopathology, etc., in appropriate models; Effect of B vitamins on the expression or function of AD-related genes; Blood brain barrier and cerebrovascular endothelial function in relation to B vitamins."