Systematic Review of EEG Coherence in Alzheimer's Disease.

BACKGROUND: Magnitude-squared coherence (MSCOH) is an electroencephalography (EEG) measure of functional connectivity. MSCOH has been widely applied to investigate pathological changes in patients with Alzheimer's disease (AD). However, significant heterogeneity exists between the studies using MSOCH. OBJECTIVE: We systematically reviewed the literature on MSCOH changes in AD as compared to healthy controls to investigate the clinical utility of MSCOH as a marker of AD. METHODS: We searched PubMed, Embase, and Scopus to identify studies reporting EEG MSCOH used in patients with AD. The identified studies were independently screened by two researchers and the data was extracted, which included cognitive scores, preprocessing steps, and changes in MSCOH across frequency bands. RESULTS: A total of 35 studies investigating changes in MSCOH in patients with AD were included in the review. Alpha coherence was significantly decreased in patients with AD in 24 out of 34 studies. Differences in other frequency bands were less consistent. Some studies showed that MSCOH may serve as a diagnostic marker of AD. CONCLUSION: Reduced alpha MSCOH is present in patients with AD and MSCOH may serve as a diagnostic marker. However, studies validating MSCOH as a diagnostic marker are needed.

[Having a driver's license when suspected of impaired cognitive functions].

Licensed physicians in Denmark are obliged to assess fitness to drive a car in patients suspected of impaired cognitive functions. Existing regulations stipulate, that fitness to drive can be assessed through screening of cognitive function using a test of orientation, clock-drawing and ability to recall three words. Evidence in support of this screening procedure seems sparse. Based on relevant published studies the authors of this review find, that no existing simple "off-road" test reliably assesses fitness to drive. In some settings combined neuropsychological- and simulator drive tests seem promising.