Food preservative enhances schizophrenia treatment

February 1, 2018, Elsevier

The common food preservative sodium benzoate improves symptoms in clozapine-resistant schizophrenia patients, according to a new study published in Biological Psychiatry. The randomized, double-blind, placebo-controlled trial led by Hsien-Yuan Lane, M.D., Ph.D., of China Medical University, Taiwan, showed that adding on sodium benzoate to the antipsychotic clozapine improved symptoms in patients who did not see results with any other medications, providing a new option for the hardest-to-treat patients.

"Clozapine is considered the last-line antipsychotic agent for with refractory schizophrenia," said Dr. Lane, referring to patients whose symptoms do not respond to available antipsychotics. But an estimated 40-70 percent of patients with refractory schizophrenia fail to improve even with clozapine, referred to as "clozapine-resistant", exhausting all potential options for . The new study is the first to demonstrate that benzoate—which has been shown to enhance other antipsychotic drugs—works in clozapine-resistant patients.

"If the finding can be confirmed, this approach may bring hope for treating patients with the most refractory schizophrenia," said Dr. Lane.

The 60 patients with schizophrenia included in the study were all taking clozapine, and received a placebo or sodium benzoate as an add-on treatment for six weeks. First author Chieh-Hsin Lin, M.D., Ph.D., of Chang Gung University College of Medicine, Taiwan, and colleagues tested two different doses of sodium benzoate (1 or 2 grams per day) to find which offered the biggest impact on symptoms with minimal side effects.

Compared with the placebo, sodium benzoate improved negative symptoms, such as lack of emotion and motivation, which have a greater influence on a patient's functional outcome than the more prominent psychotic symptoms. The higher dose of sodium benzoate also improved ratings of overall symptoms and quality of life. Although sodium benzoate has improved cognitive function when combined with other antipsychotics in previous studies, the add-on treatment had no influence on cognitive function in this study—in the paper, Dr. Lin and colleagues suggest that a higher dose or longer duration of treatment may be needed for these effects. Importantly, the patients taking sodium benzoate had no side effects, confirming the treatment is safe to use at the doses tested.

Sodium benzoate works by preventing the breakdown of D-serine, a brain chemical that plays an important role in signaling that is disrupted in the brains of people with schizophrenia. "Receptors for D-serine are long-standing targets for medication development in schizophrenia and sodium benzoate is probably the first meaningful tool that we have had to influence this target," said John Krystal, M.D., Editor of Biological Psychiatry. Although more studies are needed to learn how sodium benzoate enhances clozapine treatment in these patients, Dr. Krystal says that "this study highlights the importance for treatment of understanding the molecular switches that can be thrown to normalize brain circuit function."

Explore further: Clozapine benefits those with tx-resistant schizophrenia

More information: Chieh-Hsin Lin et al, Sodium Benzoate, a D-amino Acid Oxidase Inhibitor, Added to Clozapine for the Treatment of Schizophrenia: A Randomized, Double-Blind, Placebo-Controlled Trial, Biological Psychiatry (2017). DOI: 10.1016/j.biopsych.2017.12.006

Related Stories

Clozapine benefits those with tx-resistant schizophrenia

December 1, 2015
(HealthDay)—Clozapine reduces symptoms in patients with schizophrenia who don't benefit from other antipsychotic medications, according to research published online Nov. 6 in The American Journal of Psychiatry.

Better options for people with treatment-resistant schizophrenia

November 6, 2015
In real-world settings, patients with schizophrenia whose symptoms do not respond to standard antipsychotic medications have better outcomes if they are switched to clozapine instead of another standard antipsychotic. They ...

Scientists researching drugs that could improve brain function in people with schizophrenia

October 12, 2017
Virginia Commonwealth University researchers are testing if drugs known as HDAC inhibitors improve cognition in patients with schizophrenia who have been treated with the antipsychotic drug clozapine.

Sodium oxybate promising for Parkinson's, daytime sleepiness

November 8, 2017
(HealthDay)—For patients with Parkinson's disease (PD) and excessive daytime sleepiness (EDS), sodium oxybate seems effective and well-tolerated, according to a study published online Nov. 6 in JAMA Neurology.

An ingredient in cannabis may be useful for treating psychosis – new study

December 15, 2017
Psychiatric patients treated with a substance found in cannabis, cannabidiol, showed a significant reduction in psychotic symptoms and were also more likely to be rated as "improved" by their psychiatrist, our latest study ...

Recommended for you

Infants are able to learn abstract rules visually

February 22, 2018
Three-month-old babies cannot sit up or roll over, yet they are already capable of learning patterns from simply looking at the world around them, according to a recent Northwestern University study published in PLOS One.

Color of judo uniform has no effect on winning

February 22, 2018
New research on competitive judo data finds a winning bias for the athlete who is first called, regardless of the colour of their uniform. This unique study, published in Frontiers in Psychology, puts to rest the debate on ...

Antidepressants are more effective than placebo at treating acute depression in adults, concludes study

February 22, 2018
Meta-analysis of 522 trials includes the largest amount of unpublished data to date, and finds that antidepressants are more effective than placebo for short-term treatment of acute depression in adults.

Smartphones are bad for some teens, not all

February 21, 2018
Is the next generation better or worse off because of smartphones? The answer is complex and research shows it largely depends on their lives offline.

How people cope with difficult life events fuels development of wisdom, study finds

February 21, 2018
How a person responds to a difficult life event such as a death or divorce helps shape the development of their wisdom over time, a new study from Oregon State University suggests.

Researchers uncover novel mechanism behind schizophrenia

February 21, 2018
An international team of researchers led by a Case Western Reserve University School of Medicine scientist has uncovered a novel mechanism in which a protein—neuregulin 3—controls how key neurotransmitters are released ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.