Unravelling cognition-Emotion mechanisms in Alzheimer's disease and frontotemporal dementia: A network analysis...

Emotion processing deficits are common in Alzheimer's disease (AD) and behavioural-variant frontotemporal dementia (bvFTD), yet few studies have examined how specific cognitive domains relate to emotion processing in these syndromes. This study investigated these relationships using network psychometrics. A total of 209 participants (56 AD, 55 bvFTD, 98 healthy controls) completed neuropsychological testing. Cognitive functions were assessed with the Addenbrooke's Cognitive Examination-III and the Sydney Language Battery, while emotion processing was measured with the Facial Affect Selection Task. Network models were estimated for each group and compared using the Network Comparison Test (NCT). Both patient groups showed impaired emotion recognition versus controls. Network density was highest in bvFTD (.62), followed by AD (.44), with controls showing the sparsest network (.16). In AD, emotion processing was associated with semantic comprehension and semantic knowledge, whereas in bvFTD, emotion processing related more closely to verbal fluency. Centrality indices supported these syndrome-specific patterns. NCT results showed no significant global differences in overall strength (St = .55, p = .411) or structure (Mt = .34, p = .529) between AD and bvFTD networks, indicating comparable overall organization despite differing functional roles of specific nodes. These findings suggest disease-specific cognitive-emotion associations: semantic mechanisms in AD and fluency-related mechanisms in bvFTD. Importantly, however, contributions of other cognitive processes, not measured here, are also plausible. Overall, the study highlights both shared and distinct patterns characterizing emotion processing impairments across dementias, offering insights for developing tailored interventions targeting syndrome-specific cognitive profiles.