Does reversible MCI exist?

Abstract

Few studies have documented that some subjects affected by Mild Cognitive Impairment (MCI) do not develop dementia during the clinical period of observation and actually improve (reversible MCI) or remain stable. Aim: this study investigates whether reversible MCI is a stable clinical entity and its characteristics. Baseline socio-demographic, behavioral and cognitive features of 150 MCI subjects, referred to our memory clinic, were compared on the basis of the clinical evolution (progression to dementia, stable MCI, reverted MCI at 12 (T1) and 24 (T2) months follow-up. Thirty-nine percent had a diagnosis of dementia at T2 (progressed MCI), 47% had a diagnosis of MCI at both T1 and T2 (stable MCI), 9% had a cognitively unimpaired state at both T1 and T2 (reverted MCI) and 5% were cognitively unimpaired at T1 and impaired at T2 (temporary reverted MCI). Progressed MCI had socio-demographic and clinical characteristics similar to stable MCI but were at baseline cognitively more impaired, had more frequently a MMSE score < 27/30 (p < .05). Stable MCI showed a global improvement at T1 returning to a baseline condition at T2. Temporary reverted MCI had socio-demographic characteristics similar to stable MCI and had more frequently a MMSE score > 28/30 (p < .05), their evolution were similar to stable MCI but with greater cognitive scores. Reverted MCI were younger and more educated than other MCI groups and they were more frequently treated with antidepressant drugs (p < .05). Among the neuropsychological measures, temporary reverted MCI performed worse than reverted MCI in delayed prose recall (p < .05). Reversible MCI is an unstable clinical entity, as some patients can only temporarily revert to a cognitive normal condition likely due to a “practice” effect that characterized also stable MCI. Baseline neuropsychological evaluation is helpful in identifying MCI subjects that will temporarily revert, whereas depression is associated with true reversible MCI.