Relationship between executive dysfunction and neuropsychiatric symptoms and impaired instrumental activities of daily living among patients with very mild Alzheimer's disease

Objectives Patients with Alzheimer's disease (AD) experience a gradual loss in their ability to perform instrumental activities of daily living (IADLs) from the early stage. A better understanding of the possible factors associated with IADL decline is important for the development of effective rehabilitation and support programs for patients with AD. Thus, we examined the relationships between comprehensive cognitive functions and neuropsychiatric symptoms and IADLs in patients with very mild AD. Methods In total, 230 outpatients with probable AD were recruited from the Memory Clinic at Kumamoto University Hospital between May 2007 and October 2016. All patients scored >= 21 points on the Mini-Mental State Examination at the first assessment. Relationships between the subdomains of the Lawton IADL scale and neuropsychological/neuropsychiatric tests were examined by multiple regression analysis. All analyses were performed separately in men and women. Results In female patients, scores on the Frontal Assessment Battery were significantly associated with telephone use ability, shopping, and ability to handle finances. Apathy scores in the Neuropsychiatric Inventory (NPI) were associated with telephone use ability, housekeeping, responsibility for own medications, and ability to handle finances. NPI agitation scores were associated with food preparation and housekeeping. Geriatric Depression Scale scores were associated with telephone use ability and ability to handle finances. In male patients, only NPI apathy scores were associated with telephone use ability. Conclusions These results suggest the importance of properly assessing executive function, depression, and apathy at interventions for impaired IADLs among female patients with very mild AD.