A multi-timescale, multi-method perspective on older adult neurocognitive adaptability.

Objective: Ethical and economic values compel us to improve the screening, monitoring, and enhancement of older adult neurocognitive adaptability. Diverse contemporary theoretical and empirical perspectives highlight the multi-timescale, multi-mechanistic nature of neurocognitive adaptability. Still lacking are frameworks and methodologies that demonstrate this convergence to allow for new paradigms that harness the clinical utility of neurocognitive adaptability.Method: We present a multi-method, multi-timescale analysis of neurocognitive adaptability in a group of healthy, community-dwelling older adults from the Victoria, British Columbia region. Each participant completed a 96-trial computerized cognitive flexibility task at 4 to 6 separate laboratory visits spanning about a month. This captured within-person changes at the within-occasion and across-occasion levels (timescales of seconds and days/weeks, respectively). We used standardized clinical assessments of cognitive reserve (i.e., estimated premorbid function) and conscientiousness (a personality dimension) as cross-sectional (time-invariant) predictors in multi-level linear regression to illustrate between-person differences in within-person cognitive performance trajectories.Results: Reserve predicted cognitive performance differences at the timescale of seconds (within occasions) but did not relate to differences at the timescale of days/weeks (across occasions); in contrast, conscientiousness predicted cognitive performance differences at both timescales. Distinct processes operating within the same task (stimulus-classification vs. set-shifting) improved with practice at discrepant rates.Conclusions: Neurocognitive adaptability is underlain by multiple biopsychosocial mechanisms. Certain widely-used clinical indices (e.g., of reserve or conscientiousness) may estimate distinct types of neurocognitive adaptability relevant to maintaining functional independence into old age. Our methodology and theoretical framework assume that neurocognitive adaptability unfolds at multiple hierarchical scales of time.

Nonresponse bias in a longitudinal measurement design examining substance use across the transition out of high school.

BACKGROUND: Intensive longitudinal methods are used to study the daily-level, within-person associations between substance use and its predictors and consequences. By definition, these designs require greater respondent effort than more traditional longitudinal designs, the result of which may be increased unit nonresponse and, more importantly, nonresponse bias. The present study contrasts the nonresponse properties of a measurement burst design with those of a single 1-year follow-up ("control") design, with a particular emphasis on the retention of young adults who did not plan to graduate from college. METHODS: High school seniors (N=318) from three Midwestern schools completed an in-school baseline survey in spring 2012. Respondents were then randomized into a measurement burst or control group. Four, eight, and twelve months after baseline, young adults in the measurement burst group received a 30-min follow-up web survey, followed by 14 days of web-based daily surveys. Young adults in the control group received only a 30-min follow-up web survey 12 months after baseline. Response rates, predictors of nonresponse, and relative nonresponse biases for measures of sociodemographics, college plans, and substance use were compared between the two measurement groups. RESULTS: Compared to the control design, the measurement burst design had greater relative nonresponse bias for statistics measuring substance use, but lower relative nonresponse bias for the statistic measuring college plans. CONCLUSION: Intensive longitudinal methods have the potential to retain non-college attending young adults during the transition to adulthood. Nonresponse adjustment weights should be used to correct for any detected bias.