Executive dysfunction accompanying essential tremor

Abstract

Essential tremor (ET) is one of the most common neurological diseases. New evidence suggest that ET is associated with cognitive disorders other than motor symptoms. We aimed to investigate executive dysfunctions, which are comorbid cognitive deficiencies that may accompany ET. The study was conducted as an observational, case-control study in the Neurology Department of Ankara City Hospital in a 3-month period. The “Fahn-Tolosa-Marin Tremor Evaluation Scale” was used to rate tremor severity. Both patients and control group were subjected to the Mini Mental Test, followed by the Stroop TBAG test (TBAG is composed of the first letters of “TUBİTAK Temel Bilimler Araştırma Grubu,” which means Scientific and Technological Research Council of Turkey Basic Sciences Research Group), word fluency (category fluency), phonemic fluency (K), and abstract thinking (binary similarities, proverb interpretation) tests. Both the patient and the control group consisted of 20 women and 20 men, with age, gender, and educational background compatible. Mean age of the patient group was 34.80 ± 13.23 years, while it was 34.95 ± 10.21 years in control group. In the ET group, statistically significant impairment was detected in the Stroop Test section 5 duration and error + correction number, category fluency, binary similarity, and phonemic fluency tests compared to the control group. There was a correlation between the severity of tremor and especially Stroop, category fluency, and binary similarity tests such that, as the severity of tremor increased, these test scores deteriorated. In ET patients, an impairment, accompanying tremor, may be present in executive functions that are a part of frontal lobe functions even in younger patients. This finding may suggest that impairment in the cerebellum–thalamus–frontal lobe connection may play a role in ET pathology.

Keywords:

• Cognitive impairment
• essential tremor
• executive functions