We appreciate Dr Brenner's interest in our study of vitamin E and cognitive decline. Dr Brenner raises the issue that the vitamin E protective effect against cognitive decline may represent a delay in progression from very early Alzheimer disease with cognitive impairment to more severe disease. This hypothesis would appear unlikely given our finding that the effect was similar when we eliminated from the analyses persons who had Mini-Mental State Examination scores lower than 25, a range that many researchers would consider to represent mild cognitive impairment. Thus, the idea that vitamin E treatment initiated at the stage of early Alzheimer disease with mild cognitive impairment will delay progression to more severe disease is not fully supported by our data.
Morris MC, Evans DA, Bienias JL, Tangney CC, Wilson RS. Vitamin E Treatment Affects the Progression of Mild Cognitive Impairment to Dementia. Arch Neurol. 2003;60(2):293. doi:10.1001/archneur.60.2.292-a