Mild cognitive impairment - a five year follow-up and imaging study

Abstract

Forty-six patients with mild cognitive impairment (MCI), twenty patients with very early Alzheimer’s disease (AD), twenty psychiatric outpatients with depressive symptoms, and 24 health elderly volunteers were examined cross-sectionally using clinical and neuropsychological scales. Patients with amnestic mild cognitive impairment were followed up on average for four years. Smaller subgroups of patients were examined with an α4β2-nicotinic ligand tracer and single photon emission tomography, and diffusion tensor magnetic resonance imaging to examine white matter tract micro-integrity. One quarter of referrals to our Edinburgh neuropsychological assessment service for older people received the diagnosis of amnestic mild cognitive impairment (aMCI). Most of these also displayed non-memory cognitive deficits, without qualifying for a diagnosis of dementia. While some of the neuropsychological measures were highly specific and sensitive to early dementia, they achieved usually only one of the two for aMCI. Two fifths or our aMCI patients ‘converted’ to AD within four years of follow-up. They could be predicted at baseline with an accuracy of 75%. Typical patterns of nicotinic receptor binding and white matter integrity were found in patients with MCI.