Ondrej Bezdicek

This is a meta-analysis of studies that compare cognitive functioning between schizophrenia spectrum disorders and substance-induced psychotic disorder. PubMed, Web of Science and Google Scholar databases were systematically searched. Studies meeting the inclusion criteria were analysed. The risk of bias was assessed by QUADAS-2. Studies were pooled using a random effect model, and reported means and standard deviation (SD) were converted to Hedges’g which corrects for positive bias in Cohen’s d. Eighteen studies with 1092 patients were included in the analysis. The random effects overall meta-analysis model resulted in no overall effect. The meta-analysis for each cognitive domain showed a subtle but significant difference in executive functions, favouring substance-induced psychotic disorder. The equivalence of the groups was demonstrated by comparable performance in memory, attention, psychomotor speed, and intellectual functioning. This meta-analysis revealed that the cognitive impairment in patients with schizophrenia and substance-induced psychotic disorders groups may be quite similar. This finding indicates that the harmful effect of substance use, which leads to psychosis, may cause as severe impairment of cognitive functions as schizophrenia. Our findings also suggest that differences in executive functioning may differentiate schizophrenia from substance-induced psychotic disorder.

Both Alzheimer's (AD) and Parkinson's disease (PD) are often associated with memory dysfunction, but their pathophysiological underpinnings differ. The current research aimed to differentiate specific profiles of memory impairment due to AD versus PD. We used controlled learning and cued recall paradigm based on the Memory Binding Test (MBT) in ‘clinically cognitively normal’ controls (CN; n = 161), in patients with amnestic mild cognitive impairment due to AD (AD‐aMCI; n = 50) and due to PD (PD‐MCI; n = 22), and in PD with normal cognition ( n = 18) as based on performance in the neuropsychological battery to prevent circularity in diagnostic decision‐making. We applied analysis of covariance (ANCOVA) and Receiver Operating Characteristic (ROC) analysis to determine between‐group differences and detection potential of the MBT. We found statistically large between‐group differences with worse memory performance in paired cued recall conditions in AD‐aMCIp < .001 after Bonferroni correction), and to a lesser extent in PD‐MCI .050). The detection potential of MBT paired cued recall for differentiating memory impairment in AD‐aMCI from CN yielded an AUC of 90% (95% CI, 85–96) and an AUC of 91% (95% CI, 81–>99) between AD‐aMCI and PD‐MCI. Associative memory and binding impairment are most pronounced in AD‐aMCI in comparison to PD‐MCI and controls. Overall, the MBT is an efficient tool for the differential diagnosis of memory impairment due to the two most common neurodegenerative diseases.

Background: Cognitive impairment in Parkinson's disease (PD) is a well‐established non‐motor complication that significantly affects the quality of life and well‐being of both patients and care partners. To optimally detect mild cognitive impairment or dementia, extensive neuropsychological assessment is essential. A wide range of cognitive tests and clinical outcome assessments have been used in clinical settings, often without regard to their clinimetric quality.Methods: We performed a literature review of tests assessing attention/working memory and executive domains in PD (tests on other domains are included in an accompanying review). The selected tests were evaluated for their clinimetric properties and categorized by a panel of experts as “recommended,” “recommended with caveats,” “suggested,” or “listed” according to the International Parkinson and Movement Disorder Society Clinical Outcome Assessment Scientific Evaluation Committee guidelines.Results: A total of 30 tests were reviewed. Eight tests were “recommended,” including four tests assessing attention/working memory abilities (WAIS‐IV Digit Span, Coding and Symbol Search subtests, and Trail Making Test) and four tests assessing executive abilities (WAIS‐IV Similarities, Wisconsin Card Sorting Test, Fluency Tests, and Stroop Color‐Word Test). These tests demonstrated good to excellent levels of reliability and validity, have normative datasets, and are sensitive to change. Eight other tests were “recommended with caveats”, eleven were “suggested,” and three were “listed.”Conclusions: The recommended tests for attention/working memory and executive functioning in PD can guide PD cognitive assessment. Other tests were identified as potentially useful; however, caution is advised due to their clinimetric limitations. Further validation studies are required for these tests. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Isolated REM sleep behavior disorder (iRBD) is associated with impaired colour discrimination, cognitive deficits and morphological changes. This study evaluates whether colour discrimination deficits in iRBD are mediated by cognitive functions or related to dopaminergic denervation and brain morphology. A sample of 73 patients with iRBD and 77 controls underwent neuropsychological assessment, and colour discrimination assessment using the Farnsworth Munsell 100 Hue Test, DAT-SPECT, and MRI. The data were analyzed using multiple regression, mediation analysis, and voxel-based morphometry. Significant between-group differences were found in total colour discrimination as well as in the red-yellow spectrum. The association between iRBD and performance in the yellow-green spectrum was mediated by cognitive functions, as measured by the Montreal Cognitive Assessment. In controls, a positive correlation between the yellow-green spectrum and the left inferior frontal gyrus was observed compared to patients, however, this association was largely driven by a single data point. The performance in the green–blue spectrum was associated with the activity of dopamine transporters in the caudate nucleus. No interactions were found for total colour discrimination in any analysis. The present findings demonstrate a colour vision deficit in iRBD, which is not directly linked to any of the proposed potential explanatory mechanisms.

Background: Cognitive impairment in Parkinson's disease (PD) is a key non‐motor complication during the disease course.Objectives: A review of detailed cognitive instruments to detect mild cognitive impairment (PD‐MCI) or dementia (PDD) is needed to establish optimal tests that facilitate diagnostic accuracy.Methods: We performed a systematic literature review of tests that assess memory, language including premorbid intelligence, and visuospatial domains (for tests of attention and executive functions see accompanying review) to determine suitability to assess cognition in PD. Based on in‐depth scrutiny of psychometric and other relevant clinimetric properties, tests were rated as “recommended,” “recommended with caveats,” “suggested,” or “listed” by the International Parkinson and Movement Disorder Society (IPMDS) panel of experts according to the IPMDS Clinical Outcome Assessment Scientific Evaluation Committee guidelines.Results: We included 39 tests encompassing 48 outcome measures. Seven tests (different versions or subtests of the test counted once) were recommended, including four for memory, one for visuospatial domains, one for language (including three measures), and one for estimated premorbid intelligence. Furthermore, 10 tests (12 measures) were “recommended with caveats,” 11 were “suggested,” and 11 (15 measures) were “listed.”Conclusions: Recommended neuropsychological tests in memory, visuospatial functions, and language are proposed to guide the assessment of cognitive impairment and its progression in PD‐MCI and PDD, and for use in clinical trials to stratify participants or as outcome measures. Novel measures being developed will need extensive validation research to be “recommended.” © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Cognitive decline represents a severe non‐motor symptom of Parkinson's disease (PD) that can significantly reduce the benefits of subthalamic deep brain stimulation (STN DBS). Here, we aimed to describe post‐surgery cognitive decline and identify pre‐surgery cognitive profile associated with faster decline in STN DBS‐treated PD patients. A retrospective observational study of 126 PD patients treated by STN DBS combined with oral dopaminergic therapy followed for 3.54 years on average (SD = 2.32) with repeated assessments of cognition was conducted. Pre‐surgery cognitive profile was obtained via a comprehensive neuropsychological examination and data analysed using exploratory factor analysis and Bayesian generalized linear mixed models. On the whole, we observed a mild annual cognitive decline of 0.90 points from a total of 144 points in the Mattis Dementia Rating Scale (95% posterior probability interval [−1.19, −0.62]) with high inter‐individual variability. However, true score changes did not reach previously reported reliable change cut‐offs. Executive deficit was the only pre‐surgery cognitive variable to reliably predict the rate of post‐surgery cognitive decline. On the other hand, exploratory analysis of electrode localization did not yield any statistically clear results. Overall, our data and models imply mild gradual average annual post‐surgery cognitive decline with high inter‐individual variability in STN DBS‐treated PD patients. Nonetheless, patients with worse long‐term cognitive prognosis can be reliably identified via pre‐surgery examination of executive functions. To further increase the utility of our results, we demonstrate how our models can help with disentangling true score changes from measurement error in future studies of post‐surgery cognitive changes.

Objective: To date, very few studies have focused on structural changes and their association with cognitive performance in isolated REM sleep behaviour disorder (iRBD). Moreover, the results of these studies are inconclusive. This study aims to evaluate differences in the associations between brain morphology and cognitive tests in iRBD and healthy controls. Methods: Sixty-three patients with iRBD and thirty-six controls underwent MRI with a 3 T scanner. The cognitive performance was assessed by a comprehensive neuropsychological battery. Based on performance, the iRBD group was divided into two subgroups with (iRBD-MCI) and without mild cognitive impairment (iRBD-NC). The high-resolution T1-weighted images were analysed using an automated atlas segmentation tool, voxel-based (VBM) and deformation-based (DBM) morphometry to identify between-group differences and correlations with cognitive performance. Results: VBM, DBM and the comparison of ROI volumes yielded no significant differences between iRBD and controls. In the iRBD group, significant correlations in VBM were found between several cortical and subcortical structures primarily located in the temporal, parietal, occipital lobe, cerebellum, and basal ganglia and three cognitive tests assessing psychomotor speed and one memory test. Between-group analysis of cognition revealed a significant difference between iRBD-MCI and iRBD-NC in tests including a processing speed component. Conclusions: iRBD shows deficits in several cognitive tests that correlate with morphological changes, the most prominent of which is in psychomotor speed and visual attention as measured by the TMT-A and associated with the volume of striatum, insula, cerebellum, temporal lobe, pallidum and amygdala.

Functional impairments are a necessary requirement for the diagnosis of a dementia along with observed cognitive impairment. Comparatively, functional abilities are often relatively intact in those with mild cognitive impairment (MCI). The current research examined the associations between memory clinic participants classified as cognitively intact, amnestic MCI, and mixed/dysexecutive MCI, using Jak-Bondi criteria, and Instrumental Activities of Daily Living - Compensation Scale (IADL-C) abilities, an informant-based questionnaire that quantifies functional abilities. The associations between functional abilities as assessed with the IADL-C and performance on neuropsychological tests were also investigated. IADLC scores were obtained along with a comprehensive neuropsychological protocol on memory clinic participants (n = 100) classified as cognitively normal (CN), amnestic MCI (aMCI), or a combined mixed/dysexecutive (mixed/dys) MCI. Regression analyses were employed to determine how the IADLC related to neuropsychological test performance. On the IADLC, greater functional impairment was commonly observed in the mixed/dys MCI group compared to CN participants. Furthermore, the mixed/dys MCI group had lower scores on activities such as Money and Self-Management, Travel and Event Memory subscales compared to the CN group. Linear regression analyses found greater functional impairment in relation to lower scores on executive and episodic memory tests. Greater functional impairment as assessed with the IADL-C appears to be disproportionately associated with dysexecutive difficulty, and to a lesser degree, episodic memory.

BACKGROUND: Sensory deficits can result in limitations regarding how well neuropsychological test findings can be interpreted. Only a few studies have investigated the influence of vision alteration on neuropsychological tests. In 2012 the Czech Republic experienced mass methanol poisoning. Methanol metabolites cause histotoxic hypoxia to the optic nerve. OBJECTIVE: In the current study, the effect of the toxic damage on the parts of the visual pathway on visual and non-visual neuropsychological measures was investigated using electrophysiological methods (visual evoked potential (VEP) and optical coherence tomography (OCT) with retinal nerve fibre layer (RNFL) thickness measurement. METHODS: 53 individuals who experienced methanol poisoning participated in this research (76% men; ages 24 to 74 years, mean = 43.8±14.6 years; education 11.9±1.4 years). Each participant underwent comprehensive neurological, ophthalmological, and neuropsychological examinations. RESULTS: The results of mixed-effect models revealed significant small to a medium association between the Stroop test weak interference and Grooved Pegboard with the left eye global, nasal and temporal RNFL thickness. Also, medium associations between the Finger Tapping test and the Stroop test weak interference and left eye temporal RNFL, right eye temporal RNFL, and the latency P1 of VEP in the left eye were significant. CONCLUSION: The results of this study found a small to medium association (r = .15– .33; p = .010– .046) between RNFL thickness and cognitive visual test performance. Careful interpretation is suggested regarding results obtained from visual tests of the executive or motor functioning with participants with RNFL decrease or other types of early visual processing damage.