Slowed Processing Speed Disrupts Patient Expectancy in Late Life Depression

Area of Science:

• Geriatric Psychiatry
• Neuroscience
• Clinical Psychology

Background:

• Late-life depression (LLD) is associated with cognitive deficits, including slowed processing speed and executive dysfunction.
• These cognitive impairments are linked to poorer treatment outcomes in LLD, but the underlying mechanisms remain unclear.

Purpose of the Study:

• To investigate if slowed processing speed and executive dysfunction interfere with the development of positive treatment expectancies in older adults undergoing antidepressant treatment.
• To examine the impact of open versus hidden antidepressant administration on treatment expectancies and outcomes in LLD.

Main Methods:

• 108 older adults with depression were randomized to open (expectancy-enhancing) or hidden (expectancy-reducing) antidepressant administration for 8 weeks.
• Expectancy was measured using the Credibility and Expectancy Scale (CES).
• Moderator analyses assessed the influence of processing speed and executive function on the relationship between administration type and expectancy.

Main Results:

• The open versus hidden administration effectively manipulated treatment expectancies, with significant differences observed on CES.
• Slower processing speed, measured by the Stroop Color-Word Test, significantly moderated the effect of administration type on expectancy.
• While open administration with active drug showed greater depressive symptom improvement, no neurocognitive moderators reached statistical significance for the between-group difference.

Conclusions:

• Slowed processing speed in LLD patients impedes the formation of positive treatment expectancies, potentially contributing to reduced antidepressant response in older adults.
• Future research should explore interventions aimed at optimizing treatment expectancies to enhance therapeutic outcomes in LLD.