Modelling the impact of functionality, cognition, and mood state on awareness in people with Alzheimer's disease

To investigate the nature of the relationship between cognitive function, mood state, and functionality in predicting awareness in a non-clinically depressed sample of participants with mild to moderate Alzheimer's disease (AD) in Brazil.

People with AD (PwAD) aged 60 years or older were recruited from an outpatient unit at the Center of AD of the Federal University of Rio de Janeiro, Brazil. Measures of awareness of condition (Assessment Scale of the Psychosocial Impact of the Diagnosis of Dementia), cognitive function (Mini-Mental State Examination), mood state (Cornell Scale for Depression in Dementia), and functionality (Pfeffer Functional Activities Questionnaire) were applied to 264 people with mild to moderate AD and their caregivers. Hypotheses were tested statistically using SEM approach. Three competing models were compared.

The first model, in which the influence of mood state and cognitive function on awareness was mediated by functionality, showed a very good fit to the data and a medium effect size. The competing models, in which the mediating variables were mood state and cognitive function, respectively, only showed poor model fit.

Our model supports the notion that the relationship between different factors and awareness in AD is mediated by functionality and not by depressive mood state or cognitive level. The proposed direct and indirect effects on awareness are discussed, as well as the missing direct influence of mood state on awareness. The understanding of awareness in dementia is crucial and our model gives one possible explanation of its underlying structure in AD.