Can vitamin D help with brain function? According to research appearing in the Journal of Neurology, Neurosurgery, and Psychiatry (May 21, 2009), men with higher vitamin D levels outperformed men with low vitamin D levels in tests of attention and in the speed of processing information. Subjects of the study  were 3,369 men who were participating in the Male Aging Study. High vitamin D levels were associated with better performance on a test of psychomotor speed and visual scanning. The vitamin D/performance connection was especially evident in the older participants.