Treating prolactinoma and psychosis: medication and cognitive behavioural therapy

Treatments of psychiatric disorders, hyperprolactinemia and dopamine agonists

While the prevalence of hyperprolactinemia under antidepressants is very low, its prevalence under antipsychotics, particularly of the first generation, is high. Antipsychotics act by blocking dopamine activity at the level of the dopamine type 2 receptor (D2R). When prolactin levels exceed 80-100 ng/ml, a pituitary adenoma must be ruled out by MRI. Treatment of hyperprolactinemia is necessary only in cases with clinical symptoms of hypogonadism. Three treatment options are possible: switch to a less hyperprolactinemic antipsychotic, sex steroid supplementation or dopamine agonist (which normalizes prolactin levels in only half of cases). Fortunately, psychotic exacerbation due to the opposing effects of antipsychotics and dopamine agonists on the D2R seems very rare. When a patient presents with a macroprolactinoma, particularly with optic chiasm compression, surgery or dopamine agonists may be proposed. The agonists are effective in reducing tumor mass and improving visual defects in the majority of patients but rarely normalize prolactin levels.

Treatment of Prolactinoma

Prolactinomas are the commonest form of pituitary neuroendocrine tumor (PitNET), representing approximately half of such tumors. Dopamine agonists (DAs) have traditionally been the primary treatment for the majority of prolactinomas, with surgery considered the second line. The aim of this review is to examine the historical and modern management of prolactinomas, including medical therapy with DAs, transsphenoidal surgery, and multimodality therapy for the treatment of aggressive prolactinomas and metastatic PitNETs, with an emphasis on the efficacy, safety, and future directions of current therapeutic modalities. DAs have been the mainstay of prolactinoma management since the 1970s, initially with bromocriptine and more recently with cabergoline. Cabergoline normalizes prolactin in up to 85% of patients and causes tumor shrinkage in up to 80%. Primary surgical resection of microprolactinomas and enclosed macroprolactinomas performed by experienced pituitary neurosurgeons have similar remission rates to cabergoline. Aggressive prolactinomas and metastatic PitNETS should receive multimodality therapy including high dose cabergoline, surgery, radiation therapy (preferably using stereotactic radiosurgery where suitable), and temozolomide. DAs remain a reliable mode of therapy for most prolactinomas but results from transsphenoidal surgery in expert hands have improved considerably over the last one to two decades. Surgery should be strongly considered as primary therapy, particularly in the setting of microprolactinomas, non-invasive macroprolactinomas, or prior to attempting pregnancy, and has an important role in the management of DA resistant and aggressive prolactinomas.