Differentiating sporadic frontotemporal dementia from late-onset primary psychiatric disorders

Sporadic behavioural variant frontotemporal dementia (bvFTD) is often misdiagnosed as late-onset primary psychiatric disorder (PPD) due to overlapping symptoms and lack of biomarkers. We aimed to identify clinical features that distinguish sporadic bvFTD from PPD. Multi-centre baseline data were retrospectively retrieved and categorized into neuropsychological domains. Logistic regression models and receiver operating characteristic curves were conducted to determine discriminators. Data from 508 sporadic bvFTD and 152 PPD cases were included. Higher scores in cognitive screening [odds ratio (OR): 1.23], facial emotion processing (OR: 1.69), episodic memory (OR: 1.09), animal fluency (OR: 1.17), working memory (OR: 1.18), letter fluency (OR: 1.17) and depressive symptoms (OR: 7.41) were significantly associated with PPD (all Ps ≤ 0.010). Within a combined model, higher scores of letter fluency (OR: 1.47), cognitive screening (OR: 1.72) and lower attention (OR: 0.77) were significantly (all Ps ≤ 0.05) associated with PPD (area under the curve = 0.771). Neuropsychological measurements - letter fluency, cognitive screening and attention - can help distinguish sporadic bvFTD from late-onset PPD. Depressive symptoms and facial emotion processing emerged as potential discriminators, warranting further exploration.