The authors describe and compare two cases of sudden onset cognitive impairment in middle-aged women.

Review of clinical records, laboratorial data, neuropsychological and imagiological studies.

Two women in the sixth decade of life with a similar background and pre-illness state were admitted in the Day Unit for evaluation. They both presented sudden onset of bizarre behaviours, mood swings, unspecific speech disorder, and appetite and sleep pattern deviation, accompanying mild cognitive impairment (MCI) on neuropsychological evaluation. Both cases were submitted to intensive studies. Data and long-term follow-up revealed a frontotemporal dementia in one of the cases, and the second woman was shown to have a conversive pseudodementia.

Cognition's progressive deterioration is considered a major marker of dementia, but mild cognitive impairment is a heterogeneous clinical syndrome without criteria on current classifications of disease and limited prognostic value.