Background: Neuropsychological deficits, neuropsychiatric symptoms, and problems with instrumental activities of daily living are common in participants with mild cognitive impairment (MCI).

Objectives: To assess how subtle to mildly impaired instrumental activities of daily living (IADLs) might be related to neuropsychological abilities (including executive control and episodic memory) and neuropsychiatric symptoms (including apathy and depression) among participants with a diagnosis of MCI.

Methods: Participants were evaluated for MCI and possible dementia at an outpatient memory clinic on the basis of a comprehensive neuropsychological evaluation, a geriatric psychiatry evaluation, a magnetic resonance image of the brain, and serum studies to evaluate for a possible reversible cause of cognitive decline. A series of stepwise regression analyses were conducted whereby IADL ability was the dependent variable and neuropsychological abilities, such as executive control and episodic memory, or neuropsychiatric symptoms, including apathy and depression, were the independent or predictor variables. The presence and severity of neuropsychiatric symptoms was assessed using a modified version of the Neuropsychiatric Inventory (mNPI). Participants were grouped by MCI diagnosis status (amnestic MCI, combined dysexecutive/mixed MCI, and no MCI).

Results: Twenty-six participants were in the amnestic MCI group, 19 in the combined dysexecutive/mixed MCI group, and 36 participants did not meet criteria for MCI (non-MCI group). Groups did not differ in age, education, Mini-Mental State Examination performance, IADL abilities, estimated premorbid general intellectual abilities, or mNPI ratings for apathy and depression. Stepwise regression analyses found a robust relationship between mild IADL impairment and greater apathy (R=0.497, r²_1,69=0.247, P<.001; β=−0.497, P<.001). Depression did not enter the final model. A weaker—but statistically significant—relationship was found between mild IADL impairment and worse executive control test performance (R=0.271, r²_1,68=0.073, P<.023; β=0.271, P<.23). Episodic memory did not enter the final model. When both apathy and executive control were assessed as related to IADL impairment, only apathy entered the final model (R=0.497, R²_1,69=0.247, P<.001; β=−0.497, P<.001).

Conclusion: Mildly impaired IADL functioning can negatively affect quality of life. Moreover, apathy may be amenable to treatment. In a primary geriatric care setting, neuropsychiatric symptoms and neuropsychological abilities should be routinely assessed.