L-carnosine as an add-on to risperidone for treatment of negative symptoms in patients with stable schizophrenia: A double-blind, randomized placebo-controlled trial.

2018-04
Psychiatry research 262
- Alireza Ghajar
- Mohammad-Reza Khoaie-Ardakani
- Zahara Shahmoradi
- Amir-Reza Alavi
- Mohsen Afarideh
- Mohammad-Reza Shalbafan
- Maryam Ghazizadeh-Hashemi
- Shahin Akhondzadeh

PubMed: 29427913
DOI: 10.1016/j.psychres.2018.02.012

Study Design

Type: Randomized Controlled Trial (RCT)
Population: 63 patients with chronic schizophrenia, who were clinically stable on a stable dose of risperidone
Methods: randomized, double-blind, placebo-controlled pilot study; patients randomly assigned to l-carnosine (2 gr/day in two divided doses) or placebo for eight weeks
Blinding: Double-blind
Duration: 8 weeks

Since l-carnosine has shown effectiveness in improvement of cognition in patients with schizophrenia, this 8-week, randomized, double-blind, placebo-controlled pilot study was conducted. Sixty-three patients with chronic schizophrenia, who were clinically stable on a stable dose of risperidone, entered the study. The patients were randomly assigned to l-carnosine (2 gr/day in two divided doses) or placebo for eight weeks. The patients were assessed using the positive and negative syndrome scale (PANSS), extrapyramidal symptom rating scale (ESRS), and Hamilton depression rating scale (HDRS) during the study course. Sixty patients completed the trial. L-carnosine resulted in greater improvement of negative scores as well as total PANSS scores but not positive subscale scores compared to placebo. HDRS scores and its changes did not differ between the two groups. Both groups demonstrated a constant ESRS score during the trial course. Frequency of other side effects was not significantly different between the two groups. In a multiple regression analysis model (controlled for positive, general psychopathology, depressive and extrapyramidal symptoms, as well as other variables), the treatment group significantly predicted changes in primary negative symptoms. In conclusion, l-carnosine add-on therapy can safely and effectively reduce the primary negative symptoms of patients with schizophrenia.

Research Insights

L-Carnosine→Improved Negative Symptom
L-carnosine resulted in greater improvement of negative scores as well as total PANSS scores but not positive subscale scores compared to placebo.
Effect
Beneficial
Effect size
Moderate
Dose
2 gr/day in two divided doses
L-Carnosine→Reduced Depression Symptoms
HDRS scores and its changes did not differ between the two groups.
Effect
Neutral
Effect size
Small
Dose
2 gr/day in two divided doses
L-Carnosine→Reduced Extrapyramidal Symptoms
Both groups demonstrated a constant ESRS score during the trial course.
Effect
Neutral
Effect size
Small
Dose
2 gr/day in two divided doses
L-Carnosine→Reduced Negative Symptom Score
L-carnosine resulted in greater improvement of negative scores as well as total PANSS scores but not positive subscale scores compared to placebo.
Effect
Beneficial
Effect size
Moderate
Dose
2 gr/day in two divided doses
L-Carnosine→Reduced Positive Symptom
L-carnosine resulted in greater improvement of negative scores as well as total PANSS scores but not positive subscale scores compared to placebo.
Effect
Neutral
Effect size
Small
Dose
2 gr/day in two divided doses
L-Carnosine→Reduced Positive Symptom Score
L-carnosine resulted in greater improvement of negative scores as well as total PANSS scores but not positive subscale scores compared to placebo.
Effect
Neutral
Effect size
Small
Dose
2 gr/day in two divided doses
L-Carnosine→Reduced Total PANSS Score
L-carnosine resulted in greater improvement of negative scores as well as total PANSS scores but not positive subscale scores compared to placebo.
Effect
Beneficial
Effect size
Moderate
Dose
2 gr/day in two divided doses

Adverse Events Reported

L-Carnosine→Overall tolerability
Frequency of other side effects was not significantly different between the two groups.
Finding
No significant difference
Significant
No
L-Carnosine→extrapyramidal symptoms
Both groups demonstrated a constant ESRS score during the trial course.
Finding
No significant difference
Significant
No