Strengths and Limitations
cognitive decline
Strengths of the present study included its 3-group randomized design and masked administration of a comprehensive cognitive battery. Moreover, both interventions were 18 months in length, making them considerably longer than interventions of comparable content (ie, MBIs: 2 weeks to 13 weeksThe study also had several limitations. Participants, particularly in the no-intervention arm, were highly educated and healthy; this homogeneity limits the generalizability of findings. Furthermore, the interventions may help preserve rather than enhance cognition; as participants were cognitively healthy, effects may therefore only become apparent later with the emergence of cognitive decline. It was also not possible to determine any potential lasting effects of either intervention, as cognition was assessed immediately after interventions ended. However, an ongoing 2-year postintervention visit will allow us to ascertain whether any effects emerge.