Special Issue: Mild Cognitive Impairment

Abstract

Mild Cognitive Impairment (MCI) is found in Alzheimer's disease (ADMCI), Parkinson's disease (PDMCI), Lewy body dementia, cerebrovascular disease (Bradfield 1 ), sleep apnea and insomnia (Gilley 2 ). Studies have shown that monoclonal antibody treatment removes amyloid plaques from the AD brain. However, this did not result in clinical improvement in moderate and severe AD. One explanation was that the brain cells were already too damaged. Subsequent studies of mild AD and ADMCI suggested some benefit by reducing amyloid before the brain was too damaged. In June 2021, this led to the FDA approval of the monoclonal antibody, aducanumab, for the treatment of mild AD and ADMCI.This MCI Special Issue is timely, because the FDA approval of aducanumab has led to increased interest in ADMCI. Diagnosis of ADMCI is by PET imaging of brain amyloid plaques, which are already increased before patients meet clinical criteria for AD. The cost of this scan varies between $3000-$5000. This will be prohibitive for many, and there will be a need to find less expensive tests to screen for those who need the scan. Several papers in this Special Issue may help in solving this problem. Del Percio et al. 3 compared ADMCI patients with healthy controls, and conclude that low-cost EEG systems with few electrodes could be used to monitor ADMCI. Using low-resolution brain electromagnetic tomography (LORETA), Caravaglios et al. 4 detected functional restingstate network disconnection in MCI patients, compared with healthy controls. Morabito et al. 5 used artificial intelligence high-density EEG to follow MCI patients for three months. Progression to AD was related to presence of the delta sub-band (1-4 Hz). Delayed latency of the flash visual-evoked potential-P2 (FVEP-P2) is known to assist in the diagnosis of AD and ADMCI. Arruda et al. 6 show how their FVEP-P2 Conversion Scores can standardize latency across all clinics. They then demonstrate the diagnostic accuracy of the newly developed scores. Bruña et al. 7 used magnetoencephalography to compare spectral profiles of healthy controls, patients with amnesic MCI, and individuals showing cognitive impairment without subjective complaints (IWOC). They found slowing of brain activity in MCI, but not in IWOC, suggesting that IWOC is not part of the AD continuum. All these papers suggest that further research will lead to alternative and less expensive diagnostic procedures for ADMCI and mild AD.