Changes in irritability levels during different antidepressant treatments: a naturalistic follow-up study

Background and objectives Irritability, characterised by heightened negative affect and emotional dysregulation, is clinically significant but understudied during antidepressant treatment. This study examined changes in irritability among patients with depression and anxiety disorders starting antidepressants. It also explored whether these changes were independent of improvements in depression and anxiety and if baseline irritability predicted outcomes.Methods Eighty adults with depression or anxiety were followed for two months. Assessments at baseline, 2, 4 and 8 weeks included the Brief Irritability Test, Hamilton Depression Rating Scale and Hamilton Anxiety Rating Scale. Statistical analyses assessed irritability changes and their association with outcomes.Results Irritability significantly decreased over time, independent of reductions in depression and anxiety (p < 0.001). Baseline irritability predicted depression (β = 0.185, p = 0.009) and anxiety (β = 0.195, p = 0.019) scores at two months. Irritability reductions did not differ significantly between selective serotonin reuptake inhibitors (p = 0.237).Conclusions Irritability decreases independently of depressive and anxiety symptom improvements during antidepressant treatment. Baseline irritability predicts depression and anxiety levels at two months. Addressing irritability may enhance treatment and warrants further investigation.