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80 Processing Speed Mediates the Association between Executive Functioning and Adaptive Functioning Among Older Adults
- Jordan R Hoffmeister, Scott Roye, Christopher Copeland, John Linck
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- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, p. 588
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Objective:
Cognitive decline is expected in normative aging (Cabeza et al., 2018; Salthouse, 2019), which can lead to impairments in adaptive functioning (Yam et al., 2014). Several cognitive domains have been associated with adaptive functioning in older adult samples, including processing speed and executive functioning (e.g., Nguyen et al., 2019; Vaughn & Giovanello, 2010). A recent study examining a mixed clinical sample of older adults demonstrated that processing speed was more predictive of functional decline than other cognitive domains, including aspects of executive functioning (Roye et al., 2022). Therefore, this study attempts to build on previous findings by further examining the relationships between processing speed, adaptive functioning, and executive functioning. Specifically, it investigated the extent to which processing speed mediated the associations between executive functioning and adaptive functioning.
Participants and Methods:Participants (N = 239) were selected from a clinical database of neuropsychological evaluations. Inclusion criteria were age 60+ (M = 74.0, SD = 6.9) and completion of relevant study measures. Participants were majority White (93%) women (53.1%). Three cognitive diagnosis groups were coded: No Diagnosis (N = 82), Mild Neurocognitive Disorder (NCD; N = 78), and Major NCD (N = 79). The Texas Functional Living Scale (TFLS) was used as a performance-based measure of adaptive functioning. Processing speed was measured using the Coding subtest from the Repeatable Battery for the Assessment of Neuropsychological Status. Executive functioning performance was quantified using part B of the Trail Making Test, Controlled Oral Word Association Test, and Similarities and Matrix Reasoning subtests from the WAIS-IV and WASI-II. Mediation models included age and years of education as covariates and indirect effects were assessed with bootstrapped confidence intervals (Hayes, 2020).
Results:Processing speed mediated all measures of executive functioning. The pattern was consistent for all executive functioning measures such that poorer executive functioning was associated with poorer processing speed, which was subsequently associated with poorer adaptive functioning. Direct effects were significant for all models (ps < .03), suggesting that executive functioning maintained unique associations with adaptive functioning. Follow-up analyses indicated no evidence for moderation of the mediation models based on diagnostic group.
Conclusions:These results highlight the importance of processing speed in understanding real-world implications of pathological and non-pathological cognitive aging. Processing speed mediated all relationships between executive functioning and adaptive functioning. There was no evidence for moderation of these effects, supporting generalizability regardless of neurocognitive disorder and etiologic subtype. Further investigation is warranted into the importance of processing speed in explaining associations of other cognitive domains with adaptive functioning.
49 Adaptive Functioning in a Mixed Clinical Sample of Older Adults: The Importance of Processing Speed
- Analise Roccaforte, Jordan Hoffmeister, Scott Roye, Christopher Copeland, John Linck
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- Journal:
- Journal of the International Neuropsychological Society / Volume 29 / Issue s1 / November 2023
- Published online by Cambridge University Press:
- 21 December 2023, pp. 561-562
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Objective:
The presence of cognitive impairment corresponds with declines in adaptive functioning (Cahn-Weiner, Ready, & Malloy, 2003). Although memory loss is often highlighted as a key deficit in neurodegenerative diseases (Arvanitakis et al., 2018), research indicates that processing speed may be equally important when predicting functional outcomes in atypical cognitive decline (Roye et al., 2022). Additionally, the development of performance-based measures of adaptive functioning offers a quantifiable depiction of functional deficits within a clinical setting. This study investigated the degree to which processing speed explains the relationship between immediate/delayed memory and adaptive functioning in patients diagnosed with mild and major neurocognitive disorders using an objective measure of adaptive functioning.
Participants and Methods:Participants (N = 115) were selected from a clinical database of neuropsychological evaluations. Included participants were ages 65+ (M = 74.7, SD = 5.15), completed all relevant study measures, and were diagnosed with Mild Neurocognitive Disorder (NCD; N = 69) or Major NCD (N = 46). They were majority white (87.8%) women (53.0%). The Texas Functional Living Scale was used as a performance-based measure of adaptive functioning. The Coding subtest from the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS-CD) was used to measure information processing speed. Composite memory measures for Immediate Recall and Delayed Recall were created from subtests of the RBANS (List Learning, Story Memory, and Figure Recall) and the Wechsler Memory Scale-IV (Logical Memory and Visual Reproduction). Multiple regressions were conducted to evaluate the importance of memory and information processing speed in understanding adaptive functioning. Age and years of education were added as covariates in regression analyses.
Results:Significant correlations (p < .001) were found between adaptive functioning and processing speed (PS; r = .52), immediate memory (IM; r = .43), and delayed memory (DM; r = .32). In a regression model with IM and DM predicting daily functioning, only IM significantly explained daily functioning (rsp = .24, p = .009). A multiple regression revealed daily functioning was significantly and uniquely associated with IM (rsp = .28, p < .001) and PS (rsp = .41, p < .001). This was qualified by a significant interaction effect (rsp = -.29, p = .001), revealing that IM was only associated with adaptive functioning at PS scores lower than the RBANS normative 20th percentile.
Conclusions:Results suggest that processing speed may be a more sensitive predictor of functional decline than memory among older adults with cognitive disorders. These findings support further investigation into the clinical utility of processing speed tests for predicting functional decline in older adults.