Vitamin E has been studied for its ability to slow the progression of Alzheimer disease, possibly due to an interaction with free radicals and a disruption of cellular damage. Preliminary data suggests Vitamin E might improve cognitive function by decreasing plaque damage. The antioxidant effects of Vitamin E may reduce the number of free radicals that increase dopamine turnover. Population research has found that increasing intake of dietary Vitamin E is associated with increased physical performance and muscle strength in elderly people. Some researchers also think the antioxidant activity of vitamin E may slow progression of kidney disease.