Iron and copper appear to accumulate beyond normal levels in the brains of people with these diseases, and a new, Australian study published Sunday shows reducing excess iron in the brain can alleviate Alzheimer's-like symptoms—at least in mice.

A genetic mutation related to regulating iron is linked to ALS, or Lou Gehrig's disease. Zinc, on the other hand, appears to impair memory if its levels get too low or if it gets into a brain region where it doesn't belong, as it can with traumatic brain injury.

Higher Vitamin D Dietary Intake Is Associated With Lower Risk of Alzheimer’s Disease: A 7-Year Follow-up

Dementia and vitamin B12 deficiency