Clinical characteristics and neuropsychiatric profiles of young-onset dementia: a retrospective cross-sectional study at a tertiary care center in Northern Thailand

Background Data on young-onset dementia (YOD) in Thailand remain limited. We aimed to describe clinical presentation, general cognitive performance, neuropsychiatric symptoms, neuroimaging features, and selected laboratory findings across YOD subtypes in a tertiary-care cohort in Northern Thailand. Methods We conducted a retrospective cross-sectional study of 295 individuals with YOD (symptom onset Results Alzheimer’s disease (AD) and vascular dementia (VaD) were the most common subtypes. Memory impairment was the most frequent presenting complaint overall (78.3%) and was more common in AD than VaD (93.4% vs 77.8%), whereas behavioral change was more common in VaD than AD (31.1% vs 13.2%). General cognitive scores did not significantly differ between AD and VaD. Neuropsychiatric symptoms were frequent, with aberrant motor behavior (42.2%) and irritability/lability (35.1%) being the most prevalent domains. Regarding neuroimaging features, a substantial burden of subcortical and basal ganglia lesions co-occurred predominantly within the VaD group. Behavioral variant frontotemporal dementia (bvFTD) accounted for 3.7% of cases; most met the International Behavioral Variant FTD Criteria Consortium (FTDC) criteria for probable bvFTD. All tested participants had non-reactive HIV results, and reactive syphilis screening results were uncommon and were not supported by confirmatory treponemal testing. Conclusion Presenting complaints differed between young-onset AD and VaD despite similar general cognitive performance, underscoring the importance of informant history and multimodal assessment for accurate subtyping. Frequent motor-related neuropsychiatric symptoms highlight the clinical relevance of subcortical/basal ganglia lesion burden in this cohort.