Characterization of everyday functioning in mild cognitive impairment: a direct assessment approach

To evaluate the degree and pattern of functional difficulties in mild cognitive impairment (MCI) via direct observation of everyday task performance.

MCI (n = 25), mild Alzheimer's disease (AD; n = 25), and control (n = 18) participants performed three everyday tasks of increasing complexity.

Although caregivers reported no functional difficulties in MCI, direct observation measures of overall impairment and total errors showed MCI participants performed worse than controls, but better than AD participants, even on simple tasks. MCI and control participants exhibited significantly more difficulty performing steps accurately (i.e. commission errors) than completing task steps (i.e. omission errors), but AD participants showed an even distribution of commissions and omissions.

Diagnostic criteria for MCI should specify mild functional deficits due to the inefficient and imprecise execution of task steps. Functional deficits characterized by omission of major task segments may indicate a diagnosis of dementia.