Imagine you’re trying to gauge how good someone is at cooking. Sure, you could ask the person themselves, or you could ask their close friends and family for their opinion. But wouldn’t it be more accurate to actually watch them cook? That’s the idea behind a study on older adults’ ability to perform instrumental activities of daily living (IADLs). The researchers wanted to see if subjective reports from the individuals themselves and their informants aligned with performance-based measures of IADLs. They found that self-reports were influenced by factors like depression and personality traits, while informants’ reports were influenced by global cognition and participant’s mood. On the other hand, performance-based measures were more objective and less impacted by these factors. The researchers argue that in assessing functional ability, especially in relation to cognitive status, performance-based measures are preferable. However, when performance-based measures are not available, informant ratings should be sought as they are less influenced by the participant’s personality and mood.

ObjectivePrevious research shows that depression and personality are independently associated with self- and informant-reports of the ability to perform instrumental activities of daily living (IADLs). However, less is known about the association between depression and personality and performance-based measures of IADLs. We aimed to determine how depression and personality predict self-and informant-reports of IADL compared to performance-based measures of IADLs in a sample of older adults with normal cognition (NC) and Mild Cognitive Impairment (MCI).MethodsParticipants consisted of 385 older adults with NC (n = 235), or a diagnosis of MCI (n = 150), aged between 76 and 99-years from the Sydney Memory and Ageing Study. Participants underwent comprehensive neuropsychological and clinical assessments to determine global cognition and clinical diagnoses. Personality traits were measured by the NEO Five-Factor Inventory (NEO-FFI) and depression by the Geriatric Depression Scale (GDS). Subjective IADLs were self- and informant-reported Bayer Activities of Daily Living (B-ADL) scales and objective IADL was the Sydney Test of Activities of Daily Living in Memory Disorders (STAM). Linear regressions examined the relationship between depression and personality and the three types of IADL measures, controlling for all covariates and global cognition.ResultsParticipant-reported IADL, although associated with global cognition, was more strongly associated with GDS and NEO-FFI scores (conscientiousness and neuroticism). Informant-reported IADL was strongly associated with both global cognition and participants’ GDS scores. STAM scores were not associated with participants’ GDS or NEO-FFI scores; instead, they were predicted by demographics and global cognition.ConclusionThese results suggest that performance-based measures of IADL may provide more objective and reliable insight into an individual’s underlying functional ability and are less impacted by the participants’ mood and personality compared to subjectively reported IADL. We argue that performance-based IADL measures are preferable when trying to accurately assess everyday functional ability and its relationship to cognitive status. Where performance-based measures are not available (e.g., in some clinical settings), informant ratings should be sought as they are less influenced by the participant’s personality and mood compared to self-reports.

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