Introduction: Alzheimer’s disease (AD) cerebrospinal fluid (CSF) biomarkers are promising tools to help identify the underlying pathology of neurocognitive disorders. In this manuscript, we report our experience with AD CSF biomarkers in 262 consecutive patients in a tertiary care memory clinic. Methods: We retrospectively reviewed 262 consecutive patients who underwent lumbar puncture (LP) and CSF measurement of AD biomarkers (Aβ1–42, total tau or t-tau, and p-tau181). We studied the safety of the procedure and its impact on patient’s diagnosis and management. Results: The LP allowed to identify underlying AD pathology in 72 of the 121 patients (59%) with early onset amnestic mild cognitive impairment (aMCI) with a high probability of progression to AD; to distinguish the behavioral/dysexecutive variant of AD from the behavioral variant of frontotemporal dementia (bvFTD) in 25 of the 45 patients (55%) with an atypical neurobehavioral profile; to identify AD as the underlying pathology in 15 of the 27 patients (55%) with atypical or unclassifiable primary progressive aphasia (PPA); and to distinguish AD from other disorders in 9 of the 29 patients (31%) with psychiatric differential diagnoses and 19 of the 40 patients (47%) with lesional differential diagnoses (normal pressure hydrocephalus, encephalitis, prion disease, etc.). No major complications occurred following the LP. Interpretation: Our results suggest that CSF analysis is a safe and effective diagnostic tool in select patients with neurocognitive disorders. We advocate for a wider use of this biomarker in tertiary care memory clinics in Canada.

Introduction: Early recognition of atypical dementia remains challenging partly because of lack of cognitive screening instruments precisely tailored for this purpose. Methods: We assessed the validity and reliability of the Dépistage Cognitif de Québec (DCQ; www.dcqtest.org), a newly developed cognitive screening test, to detect atypical dementia using a multicenter cohort of 628 participants. Sensitivity and specificity were compared to the Montreal Cognitive Assessment (MoCA). A predictive diagnostic algorithm for atypical dementia was determined using classification tree analysis. Results: The DCQ showed excellent psychometric properties. It was significantly more accurate than the MoCA to detect atypical dementia. All correlations between DCQ indexes and standard neuropsychological measures were significant. A statistical model distinguished typical from atypical dementia with a predictive power of 79%. Discussion: The DCQ is a better tool to detect atypical dementia than standard cognitive screening tests. Expanding the clinician’s tool kit with the DCQ could reduce missed/delayed identification of atypical dementia and accelerate therapeutic intervention.

Objective We aimed to validate the Dépistage Cognitif de Québec (DCQ; www.dcqtest.org) , a new cognitive screening tool for atypical degenerative syndromes, in the oldest old. Methods The DCQ was developed by expert behavioural neurologists and clinical neuropsychologists based on updated criteria for Alzheimer’s disease, primary progressive aphasia, and behavioural variant frontotemporal dementia. It targets five relevant cognitive domains: Memory, Visuospatial, Executive, Language, and Behaviour. Validation was performed using a prospective community-based sample consisting of 53 healthy French-speaking Canadian volunteers aged between 80 and 94 years old. Normative data were derived from participants with no history of cognitive difficulties and a Montreal Cognitive Assessment (MoCA) score ≥ 24. Results The mean DCQ total score (out of 100) was 84.65 (SD = 6.33). Pearson’s correlation coefficient showed a moderate, but significant, correlation (r = 0.36, p < .01) with the MoCA. Normative data shown in percentiles were stratified by age and education for DCQ total score and for each of the five cognitive domains. Conclusions This study suggests that the DCQ is a valid cognitive screen­ing test in the oldest old. It is proposed that the DCQ can help early identification of atypical degenerative syndromes.

Background Cognitive abilities between monolingual and bilingual individuals may differ, making it important to validate new cognitive screening tools using psychometric testing. Otherwise assessments could be subject to misinterpretation, leading to inaccurate diagnoses. The current project aimed to compare healthy older monolingual and bilingual anglophones on the English version of a new cognitive screening test designed for better recognition of atypical dementia; the Dépistage Cognitif de Québec (DCQ, www.dcqtest.org). The DCQ was developed at la Clinique Interdisciplinaire de mémoire de Québec, and its psychometric properties have been well studied, including its sensitivity and specificity to detect atypical dementia compared to current standardized cognitive screening tests (Laforce et al., 2018; Sellami et al., 2018). Methods The DCQ was administered by qualified psychometricians to 85 healthy native English‐speaking participants aged 50 years and over, in various sites across North America. The Montreal Cognitive Assessment (MoCA) was used to determine participants’ eligibility. Language proficiency was established using the Language Experience and Proficiency Questionnaire (LEAP‐Q). Results Amidst the anglophone participants recruited, 30 monolingual anglophones and 29 bilingual anglophones met the inclusion criteria. The two groups had similar age, education and MoCA scores. Monolinguals and bilinguals were compared on their total DCQ scores as well as on each of the 5 indexes of the DCQ: Memory, Visuospatial, Executive, Language and Behavioural. Statistical analysis showed a significant advantage for the bilingual participants on the total DCQ scores and on the Language index, which was later washed out following a Bonferroni correction. No significant differences were found between groups on any of the other indexes. Conclusion This study is the first to explore psychometric properties of the DCQ in older monolingual and bilingual participants tested in their native language. The results highlight the importance of identifying and characterizing linguistic diversity before using new screening tools in clinical settings. The potential cognitive advantages of bilingualism, even in healthy older adults, should be considered when interpreting test data and explicitly discussed in neuropsychological reports. Similar studies should be conducted for all future cognitive screening measures, especially to further examine the differences between groups on language‐related tasks.

Aims and Objectives: Cognitive abilities between monolingual and bilingual individuals may differ, making it an important factor to consider during the administration of cognitive screening tools. Otherwise, assessments could be subject to misinterpretation, leading to possible inaccurate diagnoses. The current project aimed to compare cognitive performance of healthy older monolingual and bilingual anglophones on the English version of a new cognitive screening test designed for better recognition of atypical dementia: the Dépistage Cognitif de Québec (DCQ; www.dcqtest.org ). Design: The DCQ was administered by qualified psychometricians to 85 native English-speaking participants aged 50 years and over, in various sites across Canada. Language proficiency was established using the Language Experience and Proficiency Questionnaire (LEAP-Q). The Montreal Cognitive Assessment (MoCA) was used to exclude individuals with cognitive impairments. Data and Analysis: Amid the anglophone participants recruited, 30 monolingual anglophones and 29 bilingual anglophones (English and French) met inclusion criteria. Groups had similar age, education, and MoCA scores. Monolinguals and bilinguals were compared on their total DCQ scores and each of the five DCQ indexes: Memory, Visuospatial, Executive, Language, and Behavioural. Findings: The bilingual participants performed better on the Language Index, which contributed to the significant bilingual advantage for the overall DCQ scores. When applying a Bonferroni correction, the differences between groups were, however, not maintained. No differences were found on any of the other indexes. Originality: This study is the first to explore psychometric properties of the DCQ in older monolingual and bilingual participants tested in their native language. Implications: Results highlight the importance of identifying and characterizing linguistic diversity before using new screening tools in clinical settings. The potential cognitive advantages of bilingualism should be considered when interpreting test data and explicitly discussed in neuropsychological reports.