A Systematic Review of Cognition in Cervical Dystonia

Abstract

Growing evidence points to a spectrum of non-motor symptoms, including cognitive difficulties that have a greater impact on functional outcomes and quality of life than motor symptoms in cervical dystonia (CD). Some cognitive impairments have been reported; however, findings are inconsistent, and described across mixed groups of dystonia. The current review aimed to examine the evidence for cognitive impairments in CD. MEDLINE, EMBASE, PsychINFO and Web of Science databases were searched. Studies were included if they met the following criteria (i) cross-sectional or longitudinal studies of adults with CD, (ii) where the results of standardised measures of cognitive or neuropsychological function in any form were assessed and reported, (iii) results compared to a control group or normative data, and (iv) were published in English. Results are presented in a narrative synthesis. Twenty studies were included. Subtle difficulties with general intellectual functioning, processing speed, verbal memory, visual memory, visuospatial function, executive function, and social cognition were identified while language, and attention and working memory appear to be relatively spared. Several methodological limitations were identified that should be considered when interpreting the evidence to describe a specific profile of cognitive impairment in CD. Clinical and research implications are discussed.

Moving on with (social) cognition in idiopathic cervical dystonia

“…SC also, at least partly, depends on this same cortico-striatal-thalamo-cortical loop, but to our surprise we did not find support for our hypothesis that CD is associated with deficits in SC. This is not in line with the results from previous studies and the recent review by O’Connor et al (2023). Previous studies point toward impaired SC in CD patients, but the results are conflicting at times and this aspect of cognition has not yet been investigated sufficiently in CD patients.…”

“…These social cognitive deficits might be partly explained by deficits in non-SC, but the large variability between research methods hampers conclusions about this point across studies (Rizzo et al, 2023). O'Connor et al (2023) conclude that SC is impaired in CD patients, but they have several concerns about the quality of the existing evidence. Sample sizes are generally small and studies use vastly different methods, making it difficult to compare results.…”

“…Historically, CD has been considered a pure motor disorder. However, growing evidence suggests that non-motor symptoms such as depression, anxiety, and cognitive deficits are part of the phenotype (Aita et al, 2022; Ben-Shlomo et al, 2002; O’Connor et al, 2023; Smit et al, 2016). It is suggested that motor and non-motor symptoms are independent factors of the disease and can be related to the same underlying neuronal networks (Timmers et al, 2017).…”

“…Studies have shown conflicting results with some showing evidence for deficits in memory (Burke et al, 2020; Monaghan et al, 2021), and different aspects of executive functions (Bugalho et al, 2006; Foley et al, 2017; Scott et al, 2003), attention and psychomotor speed (Foley et al, 2017; Jahanshahi et al, 2003; Monaghan et al, 2021) but others demonstrating intact executive functions (Burke et al, 2020; Monaghan et al, 2021), attention, and psychomotor speed (Burke et al, 2020). In their recent review, O’Connor et al (2023) conclude that in CD patients, attention, and working memory are usually intact, but that there is evidence for deficits in social cognition (SC). Furthermore, there is conflicting evidence for minor problems regarding other cognitive domains, among which mental speed, memory, and executive functioning.…”

A comprehensive cognitive analysis of cervical dystonia: A single centre study

“…Studies of cognitive function in focal dystonia have been inconsistent due to variations in study methodology, use of heterogenous focal dystonia phenotypes and small study populations. A lack of agreed standardised measures, and heterogeneity within AOICD (tremor-/non-tremor-predominant, differing dystonia phenotypes), makes generalisation across this rare condition difficult [9] .…”