Liver and inflammatory biomarker relationships to depression symptoms in healthy older adults.

INTRODUCTION:Early identification and management of physical and mental illness is vital to maintain quality of life as we age. Markers of peripheral inflammation and liver function show elevations with aging, and are also associated with depression symptoms, suggesting a similar pattern in both aging and clinical groups. METHODS:The current study examined the relationship between such markers and measures of depression/negative mood in 284 healthy older adults using data from the Australian Research Council Longevity Intervention (ARCLI). Baseline data in adults aged 60-75 included mood symptoms via Profile of Mood States and Beck Depression Inventory II, and peripheral inflammatory (TNF-α, IL-6, hs-CRP) and liver markers (GGT, ALT, AST, AST:ALT ratio) derived from blood samples. RESULTS:The inflammation and liver enzyme relationship significantly predicted mood symptoms scores. Results showed that a significant relationship between C-reactive protein (CRP) and negative mood scores on Total Mood Disturbance and four of the six subscales (all p < .01) was dependent upon higher levels of gamma-glutamyl transferase (GGT). DISCUSSION:Higher levels of normal-range liver metabolic and peripheral inflammatory markers are observed with negative mood in a healthy older sample experiencing the biological impact of aging, but in the absence of clinical depression symptoms, suggesting a possible role of oxidative stress or other biological mechanisms occurring with aging in depression etiology. Lifestyle interventions are discussed.