Challenges and opportunities for harmonization of cross-cultural neuropsychological data.

OBJECTIVE: In this position article, we highlight the importance of considering cultural and linguistic variables that influence neuropsychological test performance and the possible moderating impact on our understanding of brain/behavior relationships. Increasingly, neuropsychologists are realizing that cultural and language differences between countries, regions, and ethnic groups influence neuropsychological outcomes, as test scores may not have the same interpretative meaning across cultures. Furthermore, attempts to apply the same norms across diverse populations without accounting for culture and language variations will result in detrimental ethical dilemmas, such as misdiagnosis of clinical conditions and inaccurate interpretations of research outcomes. Given the lack of normative data for ethnically and linguistically diverse communities, it is often challenging to merge data across diverse populations to investigate research questions of global significance. Methodological Considerations: We highlight some of the inherent challenges, limitations, and opportunities for efforts to harmonize cross-cultural neuropsychological data. We also explore some of the cultural factors that should be considered when attempting to harmonize cross-cultural neuropsychological data, sources of variance that should be accounted for in data analyses, and the need to identify evaluative criteria for interpreting data outcomes of cross-cultural harmonization approaches. CONCLUSION: In the future, it will be important to further solidify principles for aggregating data across diverse cultural and linguistic cohorts, validate whether assumptions are being satisfied regarding the relationship between neuropsychological measures and the brain and/or behavior of individuals from diverse cultural and linguistic backgrounds, as well as methods for evaluating relative successful validation for data harmonization efforts. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Predictors of health status in nondepressed and nondemented individuals with Parkinson's disease.

Recent studies have shown that self-perceived health status (HS) in Parkinson's disease (PD) is associated with motor, cognitive, or mood symptoms, with the greatest association typically occurring with mood. The purpose of this study was to determine if these associations are present in nondepressed and nondemented individuals with PD by using sensitive neuropsychological measures and statistically derived factors from mood and motor scales. The best predictors of poor HS in PD participants (N = 32) without dementia or depression were mood symptoms, specific to self-reported cognitive impairment and anxiety. Bivariate correlations between HS and number of correct categories on the Wisconsin Card Sorting Test and the gait-balance factor from the Unified Parkinson's Disease Rating Scale Part III were also significant or approached significance. These findings suggest that specific mood and cognitive symptoms continue to be important factors in HS in those individuals who lack clinical levels of depression or dementia.

Verbal learning and memory in patients with dementia with Lewy bodies or Parkinson's disease with dementia.

This study compared verbal learning and memory in patients with autopsy-confirmed dementia with Lewy bodies (DLB) and patients with Parkinson's disease with dementia (PDD). A total of 24 DLB patients, 24 PDD patients, and 24 normal comparison participants were administered the California Verbal Learning Test. The three groups were matched on demographic variables, and the two patient groups were matched on the Mattis Dementia Rating Scale. The results indicated that DLB patients recalled less information than PDD patients on all but one recall measure and displayed a more rapid rate of forgetting. In contrast, the PDD patients committed a greater percentage of perseveration errors than the DLB patients. The two groups did not differ in the percentage of recall intrusion errors or any measures of recognition. A discriminant function analysis (DFA) using short-delay cued recall, percentage of perseveration errors, and List B recall differentiated the DLB and PDD groups with 81.3% accuracy. The application of the DFA algorithm to another sample of 42 PDD patients resulted in a 78.6% correct classification rate. The results suggest that, despite equivalent levels of general cognitive impairment, patients with DLB or PDD exhibit a different pattern of verbal learning and memory deficits.

The ubiquity of memory retrieval deficits in patients with frontal-striatal dysfunction.

OBJECTIVE AND BACKGROUND: Previous studies have shown that patients with frontal-striatal dysfunction demonstrate improved performance on tests of recognition memory relative to free recall memory, suggesting deficits in retrieval processes. Not all studies, however, have indicated that all patients with frontal-striatal dysfunction display this profile. In this study, we examined the ubiquity of this "retrieval deficit" profile in a relatively large sample of patients with Parkinson disease (PD) or Huntington disease (HD). METHODS: Participants included 150 patients with PD and 65 patients with HD. Patients were classified as demonstrating a retrieval deficit or not based on a comparison of their standardized performances on the Recognition Discriminability and Long-Delay Free Recall indices from the California Verbal Learning Test. RESULTS: Results indicated that 1) a retrieval deficit was more prevalent in patients with HD than PD, 2) this group difference emerged only in patients with at least a mild level of global cognitive impairment, and 3) even when the profile did emerge more frequently in patients with HD, it was present in only 44% of the patients. CONCLUSIONS: These findings suggest that not all patient groups with frontal-striatal dysfunction display a retrieval deficit profile, but in groups that do (ie, patients with HD), it is more likely to appear in individuals with greater cognitive impairment.

The impact of irrelevant dimensional variation on rule-based category learning in patients with Parkinson's disease.

This study examined the impact of irrelevant dimensional variation on rule-based category learning in patients with Parkinson's disease (PD), older controls (OC), and younger controls (YC). Participants were presented with 4-dimensional, binary-valued stimuli and were asked to categorize each into 1 of 2 categories. Category membership was based on the value of a single dimension. Four experimental conditions were administered in which there were zero, 1, 2, or 3 randomly varying irrelevant dimensions. Results indicated that patients with PD were impacted to a greater extent than both the OC and YC participants when the number of randomly varying irrelevant dimensions increased. These results suggest that the degree of working memory and selective attention requirements of a categorization task will impact whether PD patients are impaired in rule-based category learning, and help to clarify recent discrepancies in the literature.

Is a perseveration a perseveration? An evaluation of cognitive error types in patients with subcortical pathology.

This study investigated several constructs of executive functioning in a group of 77 patients with subcortical pathology. Specifically, we examined the validity of categorizing perseverative errors as "recurrent," "stuck-in-set," or "continuous," as proposed by Sandson and Albert (1984). A principal components analysis of 2 measures of recurrent perseveration, 2 measures of stuck-in-set perseveration, and 2 measures of intrusive errors yielded a 2 component solution with stuck-in-set perseverations and intrusive errors loading on Component 1, and recurrent perseverations loading on Component 2. Presence of a continuous perseveration on a graphomotor test was significantly associated with higher factor scores on Component 1, but not Component 2. The stuck-in-set perseveration and intrusion component was associated with the majority of the other neuropsychological tests administered, including tests of executive function and memory. The recurrent perseveration component was not associated with the other measures of cognitive functioning. Presence of a continuous perseveration was associated with executive function but not memory measures. This study provides evidence that recurrent perseverations are distinct from the other types of perseverative and intrusive errors, and that stuck-in-set and intrusive errors are good indicators of general cognitive functioning in patients with subcortical pathology.