The progression from Mild Cognitive Impairment to dementia in a community older population from São Paulo, Brazil

Abstract

AbstractBackgroundMild Cognitive Impairment (MCI) is a cognitive condition greatly studied around the world, considering its potential to precede dementia, but it is little investigated in Brazilian community population. This study aimed to estimate the progression from MCI to dementia in a community‐dwelling older population from São Paulo city, Brazil.MethodA two‐phase prospective cohort study evaluated a representative cluster sample of 1,370 individuals aged 60 years old and over from three different socioeconomic levels. The diagnosis of dementia was made according to DSM IV criteria. MCI was assessed at baseline, using Mini Mental State Examination (MMSE), Fuld Object Memory Evaluation (FOME) and Bayer‐Activities of Daily Living scale (B‐ADL), and classified into three subtypes: amnestic MCI (FOME < 35 and B‐ADL scale ≤ 3.19); non‐amnestic MCI‐multiple domains (MMSE < cut‐offs according to four levels of education and FOME ≥ 35 and B‐ADL scale ≤ 3.19); non‐amnestic MCI‐specific domain (executive function)(FOME ≥ 35 and verbal fluency for animals <11 and B‐ADL scale ≤ 3.19).ResultAmong 489 subjects that completed the evaluation, 42 were diagnosed with dementia. Considering the population completely evaluated, at baseline 76, 87 and 35 subjects were classified as amnestic‐MCI, non‐amnestic MCI‐multiple domains and non‐amnestic MCI‐specific domain (executive function), respectively. The rates of conversion to dementia from non‐amnestic‐multiple domains and non‐amnestic MCI‐specific domain (executive function), compared to non‐MCI, were 6.9%% (vs 5.1%) and 2.9% (vs 5.7%), respectively (no significative difference between groups). The rate of conversion to dementia from amnestic‐MCI was 23.7% (vs 5.7%)(p <0.001; OR: 5.1, 95%CI: 2.6‐10.1); specifically for amnestic‐MCI with depressive syndrome, it was 66.7% (vs 5.1%)(p <0.001; OR: 37.0, 95%CI: 6.3‐214.2).ConclusionThe findings reinforced the role of amnestic‐MCI in the progression to dementia and Alzheimer’s Disease and exhibited an additional effect of depression on this process.