Population-based case-control study of cognitive function in essential tremor

Population-based case-control study of cognitive function in essential tremorJulin Benito-Len, Elan D. Louis, Flix Bermejo-Pareja and on behalf of the Neurological Disorders in Central Spain (NEDICES) Study GroupNeurology 2006

Objectives:To determine whether patients with essential tremor (ET) have cognitive deficits when compared with controlswhether the types of cognitive deficits reported previously are also found in this large sampling of patients with ETMethodsA total of 232 patients with ET and 696 matched controls age 65 years or older (median 75 years) living in central Spain (the Neurologic Diseases in Central Spain study) underwent a neuropsychological assessment, including tests of global cognitive performance frontal executive functionverbal fluency and memory Subjects were also asked whether they had forgetfulness or depressionStudy design and populationThe data for these analyses were derived from the Neurologic Disorders in Central Spain (NEDICES) study, a longitudinal, population-based survey of the prevalence, incidence, and determinants of major age associated conditions of the elderly. The study population comprised elderly subjects, 65 years of age or older, taken from the census of three communities in central SpainDiagnostic criteria for ET (used in subjects who were examined and in those whose medical records were reviewed) were: First an action tremor of the head, limbs, or voice without any other recognizable cause. Second the tremor had to be of gradual onset (i.e., slow and progressive) and present for at least 1 year or accompanied by a family history of the same disorder (at least one reportedly affected first-degree relative). Third, on an Archimedes spiral, tremor severity had to be moderate or greater There were 256 (4.8%) prevalent patients with ET.

ResultsThe 232 patients with ET and 696 frequency-matched controls were similar in most respects, with the exception of the prevalence of self-reported depression . Median tremor duration in patients with ET was of 3 (2.0 9.8) years.A complaint of forgetfulness was also marginally more common in patients with ET than in controls subjects.

ResultsTaken together, studies demonstrate that ET is associated with poorer performance on tests of memory and frontal executive function.