Optimistic individuals are more likely to respond to SSRI antidepressants

A study of individuals with major depressive disorder found that those with higher levels of optimism were more likely to respond positively to treatment with selective serotonin reuptake inhibitors (SSRIs), a class of medications commonly prescribed for depression. However, people with depression generally reported lower optimism than their healthy peers. The study was published in the Journal of Positive Psychology.

Optimism refers to a general tendency to expect positive outcomes and to believe that negative situations will improve over time. It has been associated with greater psychological well-being, in part because optimistic individuals tend to focus on solutions rather than dwell on problems. Optimism can promote resilience by encouraging proactive coping strategies and by reducing the harmful effects of stress.

Research has also linked optimism to healthier behaviors—such as regular physical activity and strong social relationships—which may contribute to better physical health outcomes. Optimists tend to recover more quickly from illnesses and surgeries, possibly due to lower levels of stress and inflammation. However, excessive optimism can lead to unrealistic expectations and poor risk assessment, potentially resulting in disappointment or risky decisions.

Lead author Ari S. Coopersmith and colleagues aimed to explore whether dispositional optimism—optimism as a stable personality trait—could predict how individuals with major depressive disorder respond to antidepressant treatment. They compared levels of optimism between individuals with depression and healthy controls, and examined whether higher optimism would be associated with better outcomes following SSRI treatment.

SSRIs work by increasing levels of the neurotransmitter serotonin in the brain by preventing its reabsorption. They are a widely used treatment for depression, but they are not effective for everyone. Identifying predictors of treatment response could help personalize care and improve outcomes.

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The study included 86 unmedicated individuals diagnosed with major depressive disorder and 65 healthy controls. About 44% of the depressed participants and 38% of the healthy participants were men. The average age across participants was approximately 37 years.

At the start of the study and again after eight weeks, participants completed the Revised Life Orientation Test (LOT-R) to assess optimism. Depression severity was measured using the observer-rated Hamilton Depression Rating Scale (HDRS).

Forty-six individuals with depression completed eight weeks of open-label SSRI treatment. The remaining 40 were assessed prior to the implementation of this treatment protocol. Medication adherence was confirmed through pill counts and plasma drug concentration tests.

Results showed that participants with depression had significantly lower optimism than healthy controls at baseline. Importantly, among those who received SSRIs, individuals with higher pre-treatment optimism were more likely to be classified as treatment responders—defined as experiencing at least a 50% reduction in depression symptoms. Furthermore, individuals who experienced an increase in optimism over the course of treatment were also more likely to respond positively to the medication.

“Our results suggest that baseline optimism and increases in optimism during treatment are associated with increased likelihood of SSRI treatment response in MDD [major depressive disorder],” the authors concluded.

The findings suggest that optimism may play a meaningful role in depression recovery and could serve as a psychological marker of treatment responsiveness. However, the authors note that participants were aware they were receiving antidepressant medication, which may have influenced their expectations and potentially affected treatment outcomes. This open-label design limits the ability to rule out expectancy or placebo effects.

The paper, “Dispositional optimism predicts antidepressant treatment response in major depressive disorder: potential relevance for positive psychology interventions,” was authored by Ari S. Coopersmith, Owen M. Wolkowitz, Sindy H. Mellon, Gwyneth Wu, Ryan Rampersaud, Nicholas Hansen, Ethan G. Dutcher, Victor I. Reus, and Stefanie E. Mayer.