Early-Adult Head Injury and Risk for Subsequent Alzheimer's Disease

Despite numerous investigations, the relation between traumatic head injury and the development of Alzheimer's disease (AD) remains unclear (see, for example, JWN March 2000, p. 17, and Neurology 1999; 53:1959). The cross-sectional design of many of these studies makes it impossible to determine whether the head injury predisposed individuals to AD or occurred after disease onset. In the handful of prospective studies available, the association remains inconsistent. These authors used a reconstructed cohort design to examine the association between a history of early-adult head injury in a group of veterans and the development of dementia in later life.

Men were classified as "exposed" if head injury had occurred during military service and …