Dementia is Associated with a Syndrome of Global Neuropsychiatric Disturbance

Abstract

AbstractObjectiveGlobal factors have been identified in measures of cognitive performance (i.e., Spearman’s g) and psychopathology (i.e., “General Psychopathology”, “p”). Dementia is also strongly determined by the latent phenotype “δ”, derived from g. We wondered if the Behavior and Psychological Symptoms of Dementia (BPSD) might arise from an association between δ and p.Methodsδ and p were constructed by confirmatory factor analyses in data from the Alzheimer’s Disease Neuroimaging Initiative (ADNI). δ and orthogonal factors representing “domain-specific” variance in memory (MEM) and executive function (EF) were regressed onto p and orthogonal factors representing “domain-specific” variance in positive (+) and negative (-) symptoms rated by the Neuropsychiatric Inventory Nursing Home Questionnaire (NPI-Q) by multiple regression in a structural equation model (SAM) framework.ResultsModel fit was excellent (CFI = 0.98, RMSEA = 0.03). δ was strongly associated with p, (+) and (-) and strongly associated with p (r = −0.57, p<0.001). All three associations were inverse (adverse). Independently of δ, MEM was uniquely associated with (+), while ECF was associated with (-). Both associations were moderately strong. ECF was also weakly associated with p.ConclusionsDementia severity (δ) derived from general intelligence (g) is specifically associated with general psychopathology (p). This is p’s first demonstration in an elderly sample and the first to distinguish the global behavioral and psychological symptoms specific to dementia (BPSSD) from behavioral disturbances arising by way of non-dementing, albeit likely disease-specific, processes affecting domain-specific cognitive and behavioral constructs. Our findings call into question the utility of proposed regional interventions in BPSSD, and point to the need to explore global interventions against dementia-specific behavioral features.