Lindbergh Cutter A, Puente Antonio N, Gray Joshua C, MacKillop James, Miller L Stephen
a Department of Psychology , University of Georgia , Athens , GA , USA.
J Clin Exp Neuropsychol. 2014;36(10):1112-23. doi: 10.1080/13803395.2014.983464. Epub 2014 Dec 8.
Predictors of functional independence in older adults are in need. Based on findings that delay discounting, probability discounting, and the ability to respond consistently use cognitive abilities and neural systems with central relevance to functional ability, the present study evaluated whether these behavioral economic variables account for variance in everyday functioning in older adults. It was hypothesized that greater preference for immediate/probabilistic rewards and response inconsistency would independently predict decrements in instrumental activities of daily living (IADLs).
Participants included 64 community-dwelling older adults (65-85 years; mean age = 76.25 years; 76.60% female). Exclusionary criteria were neurological illness, illiteracy, substance dependence within the past 5 years, score of ≤20 on the Mini-Mental State Examination, and/or presence of dementia. Delay/probability discounting tasks consisted of a series of dichotomous selections between smaller, immediate/guaranteed and larger, delayed/probabilistic monetary values. Area under the curve (AUC) was used to index levels of discounting, while response (in)consistency was based on the percentage of contradictory responses. The Direct Assessment of Functional Status-Revised (DAFS-R) provided a performance-based assessment of IADLs. Hierarchical regression analyses were conducted to determine whether discounting preferences and response consistency accounted for variance in functional ability over and above relevant demographic characteristics.
Demographic characteristics accounted for significance variance in IADLs (p = .001, R(2) = .237). Probability discounting AUC (p = .014, ΔR(2) = .075) and response (in)consistency (p = .046, ΔR(2) = .050) each accounted for significant additional variance in functional ability, as did delay discounting response (in)consistency (p = .010, ΔR(2) = .081). Delay discounting AUC did not add significantly to the model (p = .861).
Discounting preferences and choice consistency hold potential to serve as relatively fast and inexpensive markers of functional decline, likely due to neurocognitive deterioration relevant to both behavioral economic decision making and functional independence.
需要确定老年人功能独立的预测因素。基于研究发现，延迟折扣、概率折扣以及持续做出反应的能力会用到与功能能力密切相关的认知能力和神经系统，本研究评估了这些行为经济学变量是否能够解释老年人日常功能的差异。研究假设，对即时/概率性奖励的更高偏好以及反应不一致会独立预测日常生活工具性活动（IADL）的下降。
参与者包括64名居住在社区的老年人（年龄在65 - 85岁之间；平均年龄 = 76.25岁；女性占76.60%）。排除标准为神经系统疾病、文盲、过去5年内有药物依赖、简易精神状态检查表得分≤20分和/或患有痴呆症。延迟/概率折扣任务包括在较小的即时/有保证的货币价值与较大的延迟/概率性货币价值之间进行一系列二分选择。曲线下面积（AUC）用于衡量折扣水平，而反应（不）一致性基于矛盾反应的百分比。功能状态直接评估修订版（DAFS - R）对IADL进行了基于表现的评估。进行分层回归分析以确定折扣偏好和反应一致性是否能够解释除相关人口统计学特征之外的功能能力差异。
人口统计学特征解释了IADL中的显著差异（p = .001，R(2) = .237）。概率折扣AUC（p = .014，ΔR(2) = .075）和反应（不）一致性（p = .046，ΔR(2) = .050）各自解释了功能能力中显著的额外差异，延迟折扣反应（不）一致性也是如此（p = .010，ΔR(2) = .081）。延迟折扣AUC未对模型有显著补充（p = .861）。
折扣偏好和选择一致性有可能作为功能衰退相对快速且廉价的指标，这可能是由于与行为经济学决策和功能独立性相关的神经认知衰退所致。
