The application of a neuropsychological measure of executive working memory in older adults with memory impairment

The component of working memory that the frontal cortex subserves is frequently characterized as the executive working memory (EWM). This study applied a neuropsychological measure of EWM (NPM-EWM) in older adults with memory impairment to investigate the EWM. Thirty-two older adults from the community were recruited as older healthy controls (OHCs), and 58 older adults from a memory clinic were diagnosed with mild cognitive impairment (MCI) and mild dementia (MD). Significant differences were found among the three groups in the Clinical Dementia Rating (CDR), the Chinese version of Mini-Mental State Examination (MMSE-C), and the Cognitive Abilities Screening Instrument (CASI). The NPM-EWM was applied by using the learning task of the Comprehensive Nonverbal Memory Test Battery, where the 7 scores were divided into two categories: mnemonic capacity and executive error. All OHCs, more than 50% MCI, and less than 25% of MD patients passed the NPM-EWM. The MCI-passed and MD-passed subgroups showed similar mnemonic capacity and executive errors, and both the subgroups had significantly worse performance than the OHC group. The MD-passed subgroup had a higher Hamilton Depression Rating Scale (HDRS) score than did the MD-failed subgroup. The MCI-failed subgroup had a higher Hierarchy of Care Required (HCR) level in instrumental activities of daily living (IADL) than did the MCI-passed subgroup. These findings indicated that applying the NPM-EWM for older adults with memory impairment may offer precise and tailored care to a whole person, especially for the MCI patients with poorer EWM and the MD patients with relatively intact EWM.