Stable abnormalities of contrast discrimination sensitivity in subthreshold depression: A longitudinal study

Area of Science:

• Neuroscience
• Psychiatry
• Visual Science

Background:

• Subthreshold depression (StD) is a prevalent condition that significantly increases the risk of developing major depressive disorder (MDD).
• Previous research indicates visual processing deficits in MDD patients, but their presence and stability in StD remain unclear.

Purpose of the Study:

• To investigate whether individuals with StD exhibit contrast sensitivity deficits.
• To determine if these potential deficits are stable over a 4-month period.
• To explore the potential of contrast sensitivity testing as a biomarker for depression.

Main Methods:

• Employed a contrast discrimination task (suprathreshold) and a contrast detection task (near-threshold).
• Utilized a spatial four-alternative forced-choice method and a psychophysical QUEST procedure for threshold measurement.
• Assessed participants at an initial point and again 4 months later.

Main Results:

• Individuals with StD demonstrated significantly reduced contrast discrimination sensitivity compared to controls at both initial and follow-up assessments.
• No significant differences in contrast detection sensitivity were found between the StD group and controls.
• Contrast discrimination thresholds at baseline did not predict changes in depression symptom severity over time.

Conclusions:

• Reduced contrast discrimination sensitivity appears to be a stable, trait-dependent characteristic in individuals with subthreshold depression.
• Contrast discrimination testing may serve as a valuable biomarker for identifying individuals at risk for depression.
• Contrast detection sensitivity does not appear to be affected in subthreshold depression.