Abstract

There is growing evidence of executive function deficits in mild cognitive impairment (MCI) and task switching ability has been shown to predict MCI transition to Alzheimer's disease. We tested task switching ability using a cued task switching paradigm in 27 MCI patients. Sixteen patients could perfume the task (MCI-able) and 11 could not (MCI-unable). Neuropsychological, electrophysiological, neuroanatomical, genetic, demographic, health-related data are presented for the MCI sub-groups and normal controls. The most significant finding of this study is that task-switching ability can be a powerful tool in characterizing this heterogeneous population. We found that most MCI patients exhibit some form of task-switching deficits, but to vastly different degrees. On the one hand there are individuals closer to the normal aging end of the cognitive spectrum; these individuals may present with memory deficits relative to their normal age peers but can compensate these with quasi-intact executive functions and have a high probability of remaining dementia free as long as their executive functions remain adequate. On the other side of the spectrum, there are individuals who perfume poorly on executive tasks as well as having significant episodic memory deficits. These individuals appear to have a high probability of developing AD or dying within four years. iii