It is generally accepted that Alzheimer's disease is largely a result of build-up from beta-amyloid deposits in the brain, which cause cell damage and cell death by oxidative stress. A number of studies have shown that vitamin E, an antioxidant, exerts neuroprotective properties. Francesca Mangialasche, from the Karolinska Institutet (Sweden), and colleagues analyzed data from 168 Alzheimer's patients, 166 people with mild cognitive impairment, and 187 people with normal cognitive function. The team found that people with Alzheimer's and mild cognitive impairment had lower blood levels of total tocopherols, total tocotrienols, and total vitamin E. Specifically, people with both forms of cognitive decline were 85% less likely to have the highest average levels of total tocopherols and total vitamin E. The study subjects with Alzheimer's disease and mild cognitive impairment also displayed higher levels of vitamin E-related damage markers, as compared to the subjects with normal cognitive function.  Writing that: "Both [Alzheimer's disease and mild cognitive impairment] were associated with increased vitamin E damage,” the study authors conclude that: "Low plasma tocopherols and tocotrienols levels are associated with increased odds of [mild cognitive impairment] and [Alzheimer's disease].”