Lack of Association of Apolipoprotein e ε4 Genotype with Cognitive Dysfunction in Essential Tremor

Apolipoprotein E (APOE) ε4 genotype is associated with increased risk of Alzheimer's disease and other types of dementia. The level of cognitive dysfunction and its progression are also different in accordance with different APOE genotypes among Alzheimer's disease patients. Recently, essential tremor (ET) has become regarded as a multisystem disorder and many studies have shown that ET patients have cognitive deficits and an increased risk of dementia. The role of APOE ε4 in ET patients, however, remains unidentified. In this study, we investigated the impact of APOE genotype on cognitive change in ET. Among the 69 patients enrolled, 10 patients had more than one APOE ε4 allele. The neuropsychological data of the groups having APOE ε4 and non-ε4 were similar: the proportion of cognitive impairment was not different between the ε4 and non-ε4 groups. The results of our study suggest that the possibility of cognitive declines in ET is not influenced by the APOE ε4 gene burden.