Using aripiprazole to treat new-onset hyperprolactinemia-related delusion of pregnancy

To the Editor

Delusion of pregnancy is defined as the belief that one is pregnant despite factual evidence to the contrary. Several biomechanisms have been proposed for explaining the development of delusion of pregnancy, such as the abductive inference theory and psychodynamic conflicts (Levy et al., 2014). Although numerous studies have mentioned the role of prolactin in developing delusion of pregnancy, associating hyperprolactinemia with delusion of pregnancy is still being debated, and the related treatment strategy for delusion of pregnancy has seldom been mentioned in the literature.

This letter reports a case of new-onset hyperprolactinemia-related delusionof pregnancy concurrent with risperidone treatment in a 39-year-old female patient with a 20-year history of schizophrenia. She was hospitalized because of poor drug adherence with a presentation of persecutory delusion and auditory hallucination. After being admitted, the patient was treated with 25 mg of risperidone long-acting injection (LAI) every 2 weeks. Although the psychotic symptoms remitted gradually, she presented with breast pain and galactorrhea after approximately 1 week of treatment. The serum prolactin level was found to be elevated (120 ng/mL; normal range 2.80–29.20 ng/mL), and risperidone-induced hyperprolactinemia was suggested. Meanwhile, the symptoms of delusional pregnancy occurred, which had never manifested before. The risperidone LAI was stopped and aripiprazole 20 mg per day was prescribed instead. Two weeks later, the patient’s hyperprolactinemia-related side effects improved considerably, and the delusion of pregnancy disappeared dramatically and the serum prolactin level declined to 26.0 ng/mL. However, the original psychotic symptoms relapsed, although they were eventually relieved after the aripiprazole daily dosage was increased to 30 mg.

In this patient, delusion of pregnancy appeared concurrently with risperidone-induced hyperprolactinemia and resolved with biological normalization after depot antipsychotics were substituted with oral aripiprazole (Ranjbar et al., 2015). In addition, although an improvement in delusion of pregnancy occurred under the aripiprazole treatment, other psychotic symptoms such as persecutory delusion and auditory hallucination were exacerbated. Therefore, the improvement in the delusion of pregnancy may not be attributable to the dopamine modulation, a typical explanation for the antipsychotic mechanism of aripiprazole (Aihara et al., 2004). This situation may imply some differences between the characteristics of delusion of pregnancy and other frequently observed types of delusion in schizophrenia.

No firm conclusions can be drawn from a single case report. However, these findings may remind psychiatrists to focus on the unique psychopathology of delusion of pregnancy and suggest aripiprazole in treating schizophrenia patients with delusion of pregnancy.