Changes over time in cognitive and structural profiles of head injury survivors.

Survivors of traumatic head injury often suffer chronic cognitive deficits. Considerable evidence implicates the cholinergic system in these deficits. Recently, we reported cognitive and structural abnormalities in a cohort of head injured survivors consistent with this hypothesis [see Salmond, C. H., Chatfield, D. A., Menon, D. K., Pickard, J. D., & Sahakian, B. J. (2005). Cognitive Sequelae of Head Injury: Involvement of Basal Forebrain and associated structures. Brain, 128(1), 189-200]. The stability of the cognitive and structural MRI profiles was investigated in a longitudinal study. Twenty-one survivors of moderate-severe head injury completed two comprehensive neuropsychological assessments and two structural MRI scans at least six months apart. A cohort of controls also completed these investigations. The results revealed that the cognitive and structural profiles are relatively stable from six months post-injury forward up to 3 years post-injury. Deficits in memory, attention and reaction time were found, with relative preservation of working memory, consistent with abnormalities in the cholinergic system. These findings suggest that cholinergic enhancers may be an effective treatment for cognitive deficits post-head injury in survivors up to three years post-injury.