To the Editor: Apathy or amotivation, indifference, and loss of initiative have been reported in patients with major depressive disorder or panic disorder who take serotonin reuptake inhibitors (SSRIs).¹ These symptoms occurred dose-dependently and were reversible when the SSRI was discontinued. However, apathy associated with SSRIs was inadequately judged as a residual depressive symptom or hypomanic change. There are only 14 cases in 5 reports about SSRI-induced apathy.^1–5 In those studies, the SSRIs associated with apathy were fluoxetine, fluvoxamine, and paroxetine. To our knowledge, our study reports the first case of sertraline-induced apathy syndrome.

Mrs. A, a 39-year-old woman, was referred to our clinic for panic attacks without agoraphobia, loss of appetite, and loss of sleep that had been ongoing for 6 months. She was diagnosed with panic disorder according to the DSM-IV criteria. She had no prior history such as frontal lobe lesion, drug use, or any physical illnesses. Treatment with 25 mg/day of sertraline and 25 mg/day of trazodone did not change her panic symptoms, although her sleep disturbance was improved by trazodone. The dose of sertraline was gradually increased to 50 mg/day for 2 consecutive weeks. One month after her dosage reached 50 mg/day, all of her symptoms had improved. However, she also felt that her emotions were flat. She said that this phenomenon was different from sedation or loss of motivation, and she had no depressive mood. Although she felt like nothing mattered, she did not show hypomanic moods or behavioral changes such as hyperactivity. There were no extrapyramidal symptoms such as parkinsonism or akinesia. The dose of sertraline was gradually decreased to 25 mg/day. At 2 weeks after this gradual decrease began, her apathy then disappeared without recurrent panic attacks.

Our patient experienced apathy without somnolence, hypomania, or extrapyramidal side effects after about 1 month of sertraline therapy. The apathy symptom appeared to be dose-related, and diminished rapidly after the sertraline dosage was decreased. Not only was her apathy diminished, but the improvement in her symptoms of panic disorder persisted even after the SSRI dosage was decreased. Moreover, there were no other causes to induce apathy, such as consciousness disturbance, cognitive impairment, drug use, frontal lobe lesion, or hyperthyroidism.^3,5 The characteristics of the apathy syndrome induced by sertraline in our case were similar to those in the literature about SSRI-induced apathy syndrome. Although the apathy syndrome induced by SSRIs is frequently unrecognized, as this phenomenon is delayed in onset and subtle, clinicians must be careful to watch for signs of this syndrome after initiating sertraline treatment for patients with panic disorder or depressive disorder.