RESUMO
BACKGROUND: Recent studies demonstrated benefits of cognitive intervention in mild cognitive impairment (MCI), but few studies have determined long-term effects on cognition, conversion rate to Alzheimer's disease, and the role of early intervention. METHOD: A 6-month multicomponent cognitive group intervention was applied in participants with single- or multiple-domain amnestic MCI (defined according to Petersen's criteria). One group (n = 12) received the intervention at the beginning of the study period and was compared with an active control group (n = 12) who received it after an 8-month time lag. Follow-up assessments were conducted at 15 and 28 months (study period was August 2007-December 2009). The primary outcome was change in cognitive function as determined by changes in scores on the Mini-Mental State Examination and the cognitive subscale of the Alzheimer's Disease Assessment Scale (ADAS-cog), and the secondary outcomes were change in specific cognitive and noncognitive functions and conversion to Alzheimer's disease (according to DSM-IV/NINCDS-ADRDA criteria and NAI-AA criteria for probable Alzheimer's dementia with increased level of certainty). RESULTS: Eighteen participants completed the study after 28 months. Long-term data revealed a stable intervention effect on the primary outcome ADAS-cog in the early-intervention group (P = .024). The participants in the later-intervention (control) group appeared to benefit to a lesser extent from the cognitive intervention compared to those who received it earlier. Only participants in the later-intervention group (6 of 12) converted to Alzheimer's disease during the 28-month study period. CONCLUSIONS: Benefits of our 6-month cognitive intervention on global cognitive status appear to be preserved over extended follow-up periods. Early cognitive intervention may delay conversion to Alzheimer's disease. Findings in a small sample encourage the use of the intervention in larger-scale studies. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00544856.
