Participants in each intervention group reported less difficulty with instrumental activities of daily living ( IADLs ) ( memory : effect size = 0.48 , 99 % confidence interval ( CI ) = 0.12-0 .84 ; reasoning : effect size = 0.38 , 99 % CI = 0.02-0 .74 ; speed of processing : effect size = 0.36 , 99 % CI = 0.01-0 .72 ) .