A Double-blind, Randomized, Placebo-controlled Trial of Berberine as an Adjuvant to Treat Antipsychotic-induced Metabolic Syndrome in Patients With Schizophrenia Spectrum Disorders

Schizophrenia is a severe mental illness that affects about 1% of the worldwide population. Most patients develop a chronic course with frequent relapses and exacerbation of symptoms and required to have long-term treatment. Although antipsychotic therapy is the mainstay of the management of schizophrenia, the treatment outcomes are often unsatisfactory, largely due to adverse drug reactions. Metabolic syndrome is a highly prevalent side effect incurred in antipsychotic therapy, with a prevalence of 35% in patients with severe mental illness in Hong Kong. No effective therapies are available in treating antipsychotic-induced metabolic syndrome, although some antidiabetic medications may have limited benefits in controlling weight gain and increased glucose level.

Berberine is a natural plant alkaloid isolated from the Chinese herb, Coptis chinensis (Huang-Lian), which is traditionally used for diarrhea caused by bacterial and viral infections in clinical practice. Several lines of evidence suggest that berberine has body weight-lowering, anti-diabetic, and anti-hyperlipidemic effects. One recent study has further shown that the addition of berberine significantly prevented olanzapine (OLZ)-Induced weight gain in rats and modulated the expression of multiple key genes that control energy expenditure.

In addition to the peripheral effects, berberine also broadly modulates brain biogenic amines and related receptors that are involved in the pathogenesis of antipsychotic-induced metabolic syndrome. This suggests that it may be suitable for the treatment of antipsychotic-induced metabolic disturbance.

Over the past decade, a number of studies have demonstrated comparable efficacy of berberine as mono- and combination therapy in reducing metabolic symptoms, without serious side effect. The efficacy of berberine also has been well confirmed in patients with gastrointestinal, liver, heart, and ovary disease as well as in renal-transplant recipients and healthy volunteers. It is well tolerated and only minor digestive reactions were observed, mainly nausea, diarrhea, constipation, abdominal distension and pain.

The results obtained from the clinical and animal studies of the group strongly suggest the promising effects of berberine against OLZ-induced weight gain, without changing pharmacokinetic and pharmacodynamics profile of OLZ at peripheral and central levels. This warrants further evaluation in a larger randomized controlled trial.