Cognitive impairment in “Other” movement disorders: Hidden defects and valuable clues

Abstract

There is a group of less-common movement disorders in which a clear cognitive phenotype coexists alongside the motor abnormality, and the recognition of this co-occurrence is essential to diagnose these disorders in an early phase. Examples include chorea-acanthocytosis, Niemann-Pick type C, some dominant ataxias, and pantothotenate kinase-associated neurodegeneration. However, also, in some more-common movement disorders, such as primary dystonia and essential tremor, of which the perception is that these have a more or less pure motor phenotype, cognitive deficits are commonly present, although it is not clear whether these deficits-which may be mild in the more "pure" motor disorders-have a functionally relevant impact. In both scenarios, disruption of relevant frontal-subcortical loops appears to be key, with the striatum and cerebellum as important (but not exclusive) nodes.

A Comparison Study of Cognitive and Neuropsychiatric Features of Essential Tremor and Parkinson’s Disease

“…These results are in agreement with other studies 24–26,29. ET and PD had similar deficits in specific aspects of neuropsychological functioning, particularly those thought to rely on the integrity of the prefrontal cortex, which suggests involvement of frontocerebellar circuits,57 characterized by worse performance in functions such as attention, executive function, memory, and naming. Other studies have also noted these similarities between ET and PD 26,28.…”

Non-motor symptoms in essential tremor: A review of the current data and state of the field

“…These may be classified into several distinct domains: cognitive [3], psychiatric [2], sensory [4] and other (sleep disturbance [5]). The presence of such features should come as no surprise, as non-motor features commonly accompany and seem to be a clear phenotype that coexists alongside the motor features of a wide range of other disorders of involuntary movement [6]. For many of these disorders, they are regarded as a core, but variable, component of the clinical phenotype [6].…”

Ataxia, dystonia and myoclonus in adult patients with Niemann-Pick type C

“…Vanier et al described depression and behavioral problems with aggression and withdrawal as possible psychiatric symptoms that precede the motor signs of NP-C [1]. The number of studies on cognitive functioning of patients with NP-C is limited, but the existing studies show deficits in language, information processing speed and divided attention, memory, visuospatial skills and constructional praxis [13, 14]. Deficits in social cognition and other domains contribute to the observed cognitive decline that can be one of the precursors of NP-C [8].…”