Mild Cognitive Impairment: Beyond Memory Dysfunction

Traditionally, mild cognitive impairment (MCI) has tended to be primarily characterised and diagnosed in relation to the integrity of amnestic function and thus studied accordingly. However, a more recent multidisciplinary and collaborative research approach has investigated a much wider range of cognitive, functional, structural, and behavioural integrity and is revealing an extensive and often complex range of characteristics in addition to memory dysfunction that differentiate MCI from healthy ageing. These may be of especial relevance when considering MCI as a potential prodromal stage of dementia. Several papers in this special issue report novel and important findings with respect to the search for predictors of development of dementia in patients with MCI. The paper by E. L. Abner et al. describes a new approach in the assessment of risk factors for dementia, including age, gender, education, apolipoprotein E status, family history of dementing illness, and baseline hypertension. Their results highlight the importance of objective criteria in MCI diagnosis. I. Reinvang et al. report on how studies of genetic high-risk groups, using sensitive cognitive neuroscience paradigms , indicate the potential for differences in executive function to be a cognitive marker useful for tracking development of the pathophysiological changes of Alzheimer's disease (AD). The paper by D. V. Moretti et al. reveals specific elec-troencephalographic (EEG) changes associated with atrophy of the hippocampus in people with MCI and AD, namely, that the increase of alpha3/alpha2 power ratio is correlated with atrophy of the hippocampus both in MCI and in AD patients, suggesting a possible diagnostic role of EEG markers. In a comprehensive review, B. Ferencz et al. provide an overview of brain changes in early AD and MCI, together with evidence for recent advances in neuroimaging and genetic biomarkers and the importance of altered mitochon-drial dynamics in the preclinical stages of AD. D. P. Devanand et al. discuss the outcome of their detailed and novel study that uses clinical and magnetic resonance imaging (MRI) variables to compare predictor models for the transition to AD in patients with MCI. Research priority has until relatively recently been directed to the amnestic type of mild cognitive impairment (aMCI). However, the paper by A. Poggesi et al. provides an important overview of the concept of vascular MCI and how it may signal the prodromal stages of vascular dementia or the presence of small vessel disease. It is of course important to raise awareness of MCI within the public …