MEASURING THE EFFECT OF COGNITIVE ESTIMULATION IN AN INTERVENTION STUDY, A COMPARISON OF TWO METHODS
There is fair evidence that cognitive stimulation can attenuate cognitive decline. But more precise measurements are needed to follow cognitive variations in longitudinal studies. The objective of this study was to estimate the effect of a cognitive stimulation program mediated by computers and internet on Mini Mental Status Examination (MMSE) variation of community people with 60 years or older, without previous contact with computers or the internet, comparing two measurement methods.
METHODS: Intervention study “quasi-experimental”. Bivariated and multivariated analysis by linear regression. Two multivariated regressions models were used with two outcome measurements: MMSE raw index and a percent index variation calibrated for ceiling and floor effects (RABE-HESKETH; SKRONDAL, 2008). The stimulation program consisted of 20 bi-weekly sessions of 1.5 hours each. Total population 293, 160 in the intervention group and 133 in the control group, 164,79±99,0 days of follow-up. Control variables were socio-demographic, Co morbidities, physical activity, tobacco exposure, body mass index and functional capacity. The outcome was the variation (raw index and percent variation) between initial and final cognitive capacity measured by MMSE.
RESULTS: The first adjusted analysis (raw index) showed that the positive effects were associated with the program (Coef=1,05; CI95%=0,55-1,55; p=0,000), study years (Coef=0,06; CI95%=0,0-1,2; p=0,02) and initial MMSE (Coef=-0,46; CI95%= -0,54 - -0,39; p=0,000). The second analysis showed that the positive effects were associated with the program (Coef=24,39; CI95%=14,86-33,91; p=0,000), Socio Economic Status (SES) (Coef=19,97; CI95%=2,73-37,21; p=0,02), time between the interviews (Coef=0,13; CI95%=0,05-0,21; p=0,002) and initial MMSE (Coef=-4,28; CI95%=-5,68 - -2,28; p=0,000).
CONCLUSIONS: To follow the cognitive evolution of a community population in cohort studies, would be better to use the two methods, in order to achieve a detailed vision. The first analysis was important to measure the effect itself. The second analysis was important to measure the intensity of the intervention.