Cognitive and motor functional activity in non-demented community-dwelling essential tremor cases

Many investigators have observed mild cognitive deficits in essential tremor (ET), yet the functional significance of these deficits is unclear. Also, there are very few data in which functional activity in ET has been divided into cognitively based activities (remembering appointments) versus motor-based activities (writing cheques).

The authors (1) compared functional level in ET cases versus controls, assessing functional activities that are cognitively based and those that are dependent upon both motor and cognitive factors, and (2) determined whether lower mini mental status test scores in ET cases have a functional correlate.

In a population-based study of people > or = 65 years in central Spain (NEDICES), a 37-item version of the Mini-Mental State Examination (37-MMSE) and an 11-item version of the Pfeffer Functional Activities Questionnaire (FAQ) were administered to non-demented ET cases and controls.

The FAQ was 55.5% higher (ie, lower function) in 208 cases than 3616 controls (2.8+/-4.8 vs 1.8+/-4.2, p<0.001). Cases reported more difficulty (ie, higher FAQ scores) with FAQ items that were cognitive measures as well as FAQ items that were cognitive-motor in nature. In cases, a lower 37-MMSE was associated with more difficulty on both cognitively based and cognitive-motor-based FAQ items (p<0.001).

In this large, population-based study, ET cases reported more functional difficulty than controls, and this functional difficulty was present in both cognitive and cognitive-motor domains. Lower cognitive test scores were associated with more reported functional difficulty, indicating that lower cognitive test scores in ET, rather than being inconsequential, have a clear clinical-functional correlate.