Depressive Symptoms, Positive and Negative Affect and Progression to Cognitive Disorders: The PATH Through Life Project

Abstract

Dementia is an increasing health concern for Australia with rates of diagnoses of dementia predicted to rise within our ageing population (Prince, Albanese, Guerchet, & Prina, 2014). The potential effects are widespread not only at the individual level but at a socioeconomic level with associated medical costs (Cerejeira, Lagarto, & Mukaetova-Ladinska, 2012; Wimo, Jonsson, Bond, Prince, & Winblad, 2013). Overall, this highlights the importance for medical professionals and researchers alike to focus on methods of risk reduction. One method of risk reduction will be to investigate predictors of preclinical dementia syndromes, with the aim of implementing earlier intervention to prevent or delay progression to cognitive disorders. Past research indicates that depression is predictive for the onset of dementia and cognitive impairment/decline (Diniz, Butters, Albert, Dew, & Reynolds, 2013; Gao et al 2013). However a minimal amount of research has investigated whether specific depressive symptoms and positive or negative affect are predictive of preclinical dementia syndromes. Overall, this gap in the literature suggests that further research is needed within this area. The current research was conducted in conjunction with the Personality and Total Health (PATH) Through Life Study which is a population based prospective longitudinal study. Study 1 and Study 2 consisted of a total of 2551 participants in the 60+ cohort study. The Brief Patient Health Questionnaire (BPHQ), Goldberg Anxiety Depression Scale (GADS) and Positive and Negative Affect Scale (PANAS) were administered to measure baseline symptoms of depression and positive and negative affect. A two-staged sampling design was implemented to diagnose Mild Cognitive Impairment (MCI) and Any- Mild Cognitive Disorders (Any-MCD). Study 1 (Chapter 3) examined whether baseline depressive symptoms predicted progression to MCI or Any-MCD from wave 1 to 2 and wave 2 to 3. The results suggest that depressive symptoms of lacking energy/tired, loss of interest/pleasure, loss of confidence, difficulties concentrating, feeling down, depressed or hopeless and feeling bad about oneself were significant predictors of MCI from wave 1 to 2. Depressive symptoms of lacking energy/tired, loss of interest/pleasure, loss of confidence, difficulties concentrating, feeling down, depressed or hopeless and feeling bad about oneself, psychomotor slowing, felt worse in the morning and poor appetite or overeating were significant predictors of progression to Any-MCD from wave 1 to 2. Specific symptoms including lacking energy/feeling tired, lost interest/pleasure in doing things and difficulties concentrating were stronger predictors of progression to cognitive disorders from wave 1 to 2. These symptoms remained significant when adjusting for demographics of gender and education and covariates (employment, physical activity, anxiety and depression medication, partner status smoking, high blood pressure, diabetes, stroke and heart disease); and were cross validated between two depressive measures. The results suggest that specific symptoms are more predictive of progression to cognitive disorders at distinct time points. The findings for depressive symptoms as predictors of progression to cognitive impairment from wave 2 to 3 were intriguing, indicating that endorsing “yes” to GADS items “lacking energy” and “felt slowed up” significantly decreased the odds of progressing to Any-MCD. While GADS items “lost interest,” “lost confidence,” “felt hopeless” and “lost weight” were excluded from the current analyses due to participants in the healthy/cognitive groups not endorsing “yes” to these symptoms at baseline. The BPHQ items were excluded from analyses from wave 2 to 3 due to participants not endorsing “yes” to these symptoms at baseline. Covariates including gender and partner status were significant predictors of progression to cognitive impairment. Study 2 (Chapter 4) examined whether baseline measures of positive and negative affect predicted progression to MCI or Any-MCD from wave 1 to 2 and wave 2 to 3. Positive and negative affect were not significant predictors of MCI or Any-MCD from wave 1 to 2 or wave 2 to 3. Demographics including gender and education were significant predictors of progression to cognitive impairment. Overall, the results suggest that specific depressive symptoms are predictive of progression to cognitive disorders. Our findings suggest that additional research is needed within the field to increase our understanding of the role of depressive symptomology and affect in predicting cognitive impairment. The current findings are preliminary however with further research this area could have important clinical implications particularly that depressive symptoms may need to be monitored in individuals aged 60 years and above with the intent of earlier detection, and prevention/delay of the onset of cognitive disorders.