Abstract
Intraindividual variability (IIV) in cognitive speed has the potential to be a sensitive outcome measure for evaluating cognitive improvement from lifestyle interventions. Using the Synapse Project (n = 181), a randomized controlled trial to improve cognitive ability, we evaluated if older adults who participated in productive engagement (i.e., active learning of quilting, digital photography, or both) showed a reduction in IIV compared to those in receptive engagement (i.e., using existing knowledge via social outings or rote cognitive tasks.). All participants completed their condition for 14 weeks. IIV was based on three versions of a RT flanker task. Complier average casual effect modeling was used with compliance set at 210 hours. The models indicated that compliers in the productive engagement groups did not show any significant change in their IIV. The results demonstrate that even an intensive activity intervention may not be sufficient to cause significant improvement in IIV.