The Geriatric Depression Scale: does it measure depressive mood, depressive affect, or both?

Area of Science:

• Geriatric Psychiatry
• Psychometrics
• Longitudinal Studies

Background:

• Self-report depression measures are crucial for research and clinical diagnosis.
• The Geriatric Depression Scale (GDS) is a widely used screening tool for late-life depression.
• The GDS is endorsed by prominent medical societies, highlighting its clinical significance.

Purpose of the Study:

• To determine if the Geriatric Depression Scale (GDS) scores reflect stable depressive traits, short-term depressive states, or both.
• To differentiate between enduring depressive mood and transient depressive affect using GDS scores.

Main Methods:

• A trait-state model was applied to GDS-15 scores from 753 community-dwelling older adults.
• Data were collected at four time points over a 6-year period.
• The model decomposed GDS-15 variance into stable trait, autoregressive trait, and state components.

Main Results:

• A substantial majority of GDS-15 variance was attributed to stable trait (69%) and autoregressive trait (22%) components.
• State variance accounted for a minimal proportion (9%) of the GDS-15 scores over 6 years.
• Older age and female gender were associated with greater stable trait variance in GDS scores.

Conclusions:

• Geriatric Depression Scale (GDS)-15 assessments should be interpreted as reflecting a stable, enduring trait of depressivity.
• The minimal state variance indicates that depression in older adults is a persistent condition.
• Contextual interventions alone are unlikely to produce significant changes in depressive symptoms as measured by the GDS-15.