Browsing by Author "Dixon, Ava"

Now showing 1 - 5 of 5
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    Predicting daily functioning with the modified Telephone Interview for Cognitive Status
    (Springer Nature, 2022) Dixon, Ava; Porter, Sariah; Suhrie, Kayla; Hammers, Dustin; Duff, Kevin; Neurology, School of Medicine
    Background: The modified Telephone Interview for Cognitive Status (mTICS) is a frequently used telephone-based cognitive screening measure that can distinguish between normal aging, mild cognitive impairment (MCI), and dementia. Although it has been used to predict current and future cognitive function in older adults, no studies have examined if the mTICS can predict daily functioning. Aims: The current study sought to examine the relationship between the mTICS and a performance-based measure of daily functioning. Methods: The mTICS and demographic information (age, sex, education) were collected during a telephone screening visit for 149 older adults (65-91 years in age) with amnestic MCI. Three subscales of the Independent Living Scales (ILS; Managing Money, Managing Home and Transportation, Health and Safety) were collected during a baseline visit and during a 16 month follow-up visit in a subsample of 93 individuals. Results: Using simple hierarchical regression, baseline mTICS total score combined with demographic variables significantly predicted 19-22% of baseline ILS subscale scores. Similarly, in a subsample of 93 participants with 16 month follow-up data, baseline mTICS and demographic information predicted 9-31% of ILS subscale scores at follow-up. Conclusions: The mTICS appears able to predict daily functioning in older individuals with MCI. Remote tracking of cognition and daily functioning in this at-risk group seems particularly beneficial to geriatricians and other providers, especially during COVID-19.
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    Relationship between a novel learning slope metric and Alzheimer’s disease biomarkers
    (Taylor & Francis, 2022) Hammers, Dustin B.; Suhrie, Kayla; Dixon, Ava; Gradwohl, Brian D.; Archibald, Zane G.; King, Jace B.; Spencer, Robert J.; Duff, Kevin; Hoffman, John M.; Neurology, School of Medicine
    The Learning Ratio (LR) is a novel learning score examining the proportion of information learned over successive learning trials relative to information available to be learned. Validation is warranted to understand LR's sensitivity to Alzheimer's disease (AD) pathology. One-hundred twenty-three participants across the AD continuum underwent memory assessment, quantitative brain imaging, and genetic analysis. LR scores were calculated from the HVLT-R, BVMT-R, RBANS List Learning, and RBANS Story Memory, and compared to total hippocampal volumes,18F-Flutemetamol composite SUVR uptake, and APOE ε4 status. Lower LR scores were consistently associated with smaller total hippocampal volumes, greater cerebral β-amyloid deposition, and APOE ε4 positivity. This LR score outperformed a traditional learning slope calculation in all analyses. LR is sensitive to AD pathology along the AD continuum - more so than a traditional raw learning score - and reducing the competition between the first trial and subsequent trials can better depict learning capacity.
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    Reliable change in cognition over 1 week in community-dwelling older adults: a validation and extension study
    (Oxford University Press, 2021) Hammers, Dustin B.; Suhrie, Kayla R.; Dixon, Ava; Porter, Sariah; Duff, Kevin; Neurology, School of Medicine
    Objective: Reliable change methods can aid neuropsychologists in understanding if performance differences over time represent clinically meaningful change or reflect benefit from practice. The current study sought to externally validate the previously published standardized regression-based (SRB) prediction equations developed by Duff for commonly administered cognitive measures. Method: This study applied Duff's SRB prediction equations to an independent sample of community-dwelling participants with amnestic mild cognitive impairment (MCI) assessed twice over a 1-week period. A comparison of MCI subgroups (e.g., single v. multi domain) on the amount of change observed over 1 week was also examined. Results: Using pairwise t-tests, large and statistically significant improvements were observed on most measures across 1 week. However, the observed follow-up scores were consistently below expectation compared with predictions based on Duff's SRB algorithms. In individual analyses, a greater percentage of MCI participants showed smaller-than-expected practice effects based on normal distributions. In secondary analyses, smaller-than-expected practice effects were observed in participants with worse baseline memory impairment and a greater number of impaired cognitive domains, particularly for measures of executive functioning/speeded processing. Conclusions: These findings help to further support the validity of Duff's 1-week SRB prediction equations in MCI samples and extend previous research by showing incrementally smaller-than-expected benefit from practice for increasingly impaired amnestic MCI subtypes.
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    Validating 1-Year Reliable Change Methods
    (Oxford University Press, 2021) Hammers, Dustin B.; Porter, Sariah; Dixon, Ava; Suhrie, Kayla R.; Duff, Kevin; Neurology, School of Medicine
    Objective: reliable change methods can assist in the determination of whether observed changes in performance are meaningful. The current study sought to validate previously published 1-year standardized regression-based (SRB) equations for commonly administered neuropsychological measures that incorporated baseline performances, demographics, and 1-week practice effects. Method: Duff et al.'s SRB prediction equations were applied to an independent sample of 70 community-dwelling older adults with either normal cognition or mild cognitive impairment, assessed at baseline, at 1 week, and at 1 year. Results: minimal improvements or declines were seen between observed baseline and observed 1-year follow-up scores, or between observed 1-year and predicted 1-year scores, on most measures. Relatedly, a high degree of predictive accuracy was observed between observed 1-year and predicted 1-year scores across cognitive measures in this repeated battery. Conclusions: these results, which validate Duff et al.'s SRB equations, will permit clinicians and researchers to have more confidence when predicting cognitive performance on these measures over 1 year.
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    Validation of one-week reliable change methods in cognitively intact community-dwelling older adults
    (Taylor & Francis, 2021) Hammers, Dustin B.; Suhrie, Kayla R.; Dixon, Ava; Porter, Sariah; Duff, Kevin; Neurology, School of Medicine
    Reliable change methods can assist the determination of whether observed changes in performance are meaningful. The current study sought to validate previously published standardized regression-based (SRB) equations for commonly administered cognitive tests using a cognitively intact sample of older adults, and extend findings by including relevant demographic and test-related variables known to predict cognitive performance. Method: This study applied previously published SRB prediction equations to 107 cognitively intact older adults assessed twice over one week. Prediction equations were also updated by pooling the current validation sample with 93 cognitively intact participants from original development sample to create a combined development sample. Results: Significant improvements were seen between observed baseline and follow-up scores on most measures. However, few differences were seen between observed follow-up scores and those predicted from these SRB algorithms, and the level of practice effects observed based on these equations were consistent with expectations. When SRBs were re-calculated from this combined development sample, predicted follow-up scores were mostly comparable with these equations, but standard errors of the estimate were consistently smaller. Conclusions: These results help support the validity of of these SRB equations to predict cognitive performance on these measures when repeated administration is necessary over short intervals. Findings also highlight the utility of expanding SRB models when predicting follow-up performance serially to provide more accurate assessment of reliable change at the level of the individual. As short-term practice effects are shown to predict cognitive performance annually, they possess the potential to inform clinical decision-making about individuals along the Alzheimer's continuum.