Clinical appications of EEG/MEG in AD: diagnosis, prognosis and treatment monitoring

Abstract

AbstractBackgroundElectroencephalography (EEG) and magnetoencephalography (MEG) capture neuronal functioning directly, thereby providing an objective intermediate marker between pathological changes and cognitive symptoms in neurodegenerative diseases. Both techniques are highly suitable as tools in the context of memory clinics and their use for treatment monitoring is increasingly recognized.MethodWe will highlight recent developments important for the use of EEG / MEG as diagnostic and prognostic markers in dementia and as outcome measures in Alzheimer’s disease (AD) trials.ResultIn memory clinics, both visual and quantitative EEG / MEG are being used as supportive evidence in diagnostic challenges, especially when other pathology specific –likely more invasive‐ biomarkers are not available. Increasing numbers of papers using artificial intelligence to differentiate a specific dementia type from cognitively healthy subjects report fair to excellent accuracies that are especially high for dementia with Lewy Bodies (DLB). Multi‐class classification between six memory clinic diagnoses resulted in MEG‐based diagnostic profiles describing the probability estimates of each class. These diagnostic profiles provide an informative and intuitive tool for clinical use. In pre‐clinical stages of AD spectral changes are predictive of future cognitive decline, and in the mild cognitive impairment stage it differentiates between progression into dementia due to AD or DLB. As EEG / MEG are found to be sensitive to longitudinal changes, there is increasing interest in the use of EEG as outcome measures in clinical trials. Both spectral and functional connectivity measures showed a treatment effect in phase 2 pharmacological studies in early AD, giving objective support for (subtle) clinical effects of the drug on trial. The pursuit of discovering even more sensitive, robust and complementary measures lead to novel neurophysiological markers reflecting functional connectivity, signal variability and neuronal hyperexcitability.ConclusionEEG / MEG provide diagnostic and prognostic information applicable in memory clinics. The use of sensitive conventional and novel markers in (pharmacological) trials can support clinical treatment effects and have potential to reduce the size of trials.