Vitamin D & Dementia

A growing body of research has established a significant connection between vitamin D deficiency and the risk of developing dementia, including Alzheimer's disease. A landmark study published in Neurology found that individuals with severe vitamin D deficiency were more than twice as likely to develop dementia compared to those with adequate levels.

The Research

Researchers followed over 1,600 adults aged 65 and older for an average of 5.6 years. Those with severe vitamin D deficiency (less than 25 nmol/L) had a 125% increased risk of developing dementia of any type and a 122% increased risk of Alzheimer's disease specifically.

Even moderate deficiency (25–50 nmol/L) was associated with a 53% increased risk of all-cause dementia.

Why Vitamin D Matters for the Brain

Vitamin D receptors are found throughout the brain, including areas critical for memory and cognition. Vitamin D is believed to play several important roles in brain health:

• Reducing inflammation in the brain
• Clearing amyloid plaques associated with Alzheimer's
• Protecting neurons from damage
• Supporting neurotransmitter synthesis

Are You Deficient?

Vitamin D deficiency is remarkably common. An estimated 42% of American adults are deficient, with higher rates among older adults, people with darker skin, and those who spend limited time outdoors. Many people are deficient without knowing it, as symptoms can be subtle or absent.

What You Can Do

Have your vitamin D levels checked with a simple blood test. At HAPC, we routinely test vitamin D levels as part of our comprehensive lab work. If your levels are low, supplementation under medical guidance can help bring them to an optimal range. The target range for most adults is 40–60 ng/mL.