Aim: to test if vitamin E prevents oxidative stress and loss of cognition in Alzheimer disease (AD).

Methods: 

Fifty-seven AD patients were recruited and divided in two groups: placebo or treated with 800 mg of vitamin E per day for six months. Of these 57 patients, only 33 finished the study. We measured blood oxidised glutathione (GSSG) levels and the following tests: Mini-Mental State Examination (MMSE), the Blessed-Dementia Scale and the Clock Drawing Test

Results: 

We found two groups: one of "responders" to vitamin E. In them GSSG levels are lower after the treatment and the score of cognitive tests is maintained. In the "non-responder" group vitamin E was not effective in preventing oxidative stress. In these patients cognition decreased sharply, to levels even lower than those of patients taking placebo.

Conclusion: 

Vitamin E lowers oxidative stress in some AD patients. In these it maintains cognitive status. But in those in which it does not prevent oxidative stress it is detrimental in terms of cognition. Supplementation of AD patients with vitamin E can not be recommended without determination of its antioxidant effect in each patient.