Targeted support for caregivers of patients with YOD is needed to address the higher CB in this group.

Background Southeast Asia represents 10% of the global population, yet little is known about regional clinical characteristics of dementia and risk factors for dementia progression. This study aims to describe the clinico-demographic profiles of dementia in Southeast Asia and investigate the association of onset-type, education, and cerebrovascular disease (CVD) on dementia progression in a real-world clinic setting. Methods In this longitudinal study, participants were consecutive series of 1606 patients with dementia from 2010 to 2019 from a tertiary memory clinic from Singapore. The frequency of dementia subtypes stratified into young-onset (YOD; <65 years age-at-onset) and late-onset dementia (LOD; ≥65 years age-at-onset) was studied. Association of onset-type (YOD or LOD), years of lifespan education, and CVD on the trajectory of cognition was evaluated using linear mixed models. The time to significant cognitive decline was investigated using Kaplan-Meier analysis. Results Dementia of the Alzheimer’s type (DAT) was the most common diagnosis (59.8%), followed by vascular dementia (14.9%) and frontotemporal dementia (11.1%). YOD patients accounted for 28.5% of all dementia patients. Patients with higher lifespan education had a steeper decline in global cognition (p<0.001), with this finding being more pronounced in YOD (p=0.0006). Older patients with a moderate-to-severe burden of CVD demonstrated a trend for a faster decline in global cognition compared to those with a mild burden. Conclusions There is a high frequency of YOD with DAT being most common in our Southeast Asian memory clinic cohort. YOD patients with higher lifespan education and LOD patients with moderate-to-severe CVD experience a steep decline in cognition.

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Background Posterior Cortical Atrophy (PCA) has been widely studied internationally, but there is limited data on its clinical and biomarker characteristics among Southeast Asians. We aim to describe a case series of PCA patients in this part of the world and explore how the new PCA consensus classification (Crutch et al., 2017) could be applied in this cohort. Method A retrospective review of the Singapore Young Onset Dementia (YOD) research database from a tertiary neurology center was performed. Available demographic, clinical and biomarker data of patients with a clinical diagnosis of PCA were extracted. Result Of 290 patients with YOD, ten patients (5 males; 5 females) with a clinical diagnosis of PCA were identified. Mean (SD) age of onset was 54.70 (4.11), duration between symptom onset and neurological consultation was 3.90 (1.45) years. All patients reported insidious onset and gradual progression of symptoms. Upon neurological examination, principle types of cognitive deficits seen were acalculia (80%), finger agnosia (70%), simultagnosia (60.0%) and agraphia (50%). In another sub‐group with available MRI scans (n=7), all showed biparietal cortical atrophy, five (71.0%) had concomitant bilateral medial temporal lobe atrophy and white matter hyperintensities of varying severity was noted in four (57.0%) patients. Among patients with known APOE genotyping (n=8), there was one e2e3 six e3e3 and one e4e4. Findings on cerebrospinal Ab‐42 and tau levels was available (n=7), mean (SD) of Ab‐42, phosphor‐tau and total tau levels were 525.1 (195.5)pg/ml, 72.1 (22.9)pg/ml and 611.3 (246.9)pg/ml respectively. Based on the new consensus classification for PCA (Crutch et al., 2017) and incorporating the CSF Ab‐42 criterion cut‐off for AD by Dubois et al. (2014), our series consists of one PCA‐AD (10.0%) and nine PCA‐pure (90.0%) However, if the CSF tau/ Ab‐42 ratio >0.52 (Duits et al., 2014) for biomarker diagnosis of AD is used, there would be seven PCA‐AD (70%) and three PCA‐plus (30%). Conclusion PCA patients tend to present late in clinic and greater awareness on the presentation of PCA is needed for earlier diagnosis and timely intervention. Also, the sensitivity of the different CSF criteria for AD in diagnosing PCA‐AD would require further analyses in larger cohorts.