Subtype of mild cognitive impairment in elderly patients with essential tremor

Background and Aims: Several studies have demonstrated that patients with essential tremor (ET) may also have mild cognitive impairments (MCIs), and cross-sectional and population-based studies have shown that ET is associated with prevalent dementia. Different presentations of MCI are suggested to be associated with different pathologies. For example, amnestic MCI may be associated with Alzheimer disease. Therefore, in this study, we explored whether the MCI subtype in patients with ET (MCI-ET+) is different from the MCI subtype in patients without ET attending a memory outpatient clinic (MCI-ET-). Methods: Using a case-control study design, cognitive status in MCI patients with ET and without ET was assessed by neuropsychological testing. Patients with MCI were stratified into groups: amnestic and nonamnestic MCI, or single-domain and multidomain MCI. Results: Of the 93 patients in the ET+ group and the 169 in the ET-group, 45 (48.4%) and 94 (55.6%) patients had MCI, respectively. The frequency of MCI subtypes between the 2 groups was different, such that 25 (55.6%) patients had nonamnestic MCI in the ET+ group and 68 (72.3%) patients had amnestic MCI in ET-group (χ 2 =10.195, P=0.001). Compared with the MCI-ET+ group, patients in the MCI-ET-group showed more severe impairments in verbal and visuospatial memory functions. Conclusions: ET is associated with MCI, particularly the nonamnestic subtype. These results suggest that cognitive change in patients with ET may have a different pathogenesis from that of Alzheimer disease.