Growth hormone response to sodium valproate in chronic schizophrenia

Valproate for schizophrenia

BACKGROUND

Many people with schizophrenia do not achieve a satisfactory treatment response with ordinary antipsychotic drug treatment. In these cases, various add-on medications are used, and valproate is one of these.

OBJECTIVES

To examine whether:1. valproate alone is an effective treatment for schizophrenia and schizoaffective psychoses; and2. valproate augmentation of antipsychotic medication is an effective treatment for the same illnesses.

SEARCH METHODS

We searched the Cochrane Schizophrenia Group's Study-Based Register of Trials (July 2002; February 2007; July 2012; March 04, 2016). We also contacted pharmaceutical companies and authors of relevant studies in order to identify further trials.

SELECTION CRITERIA

We included all randomised controlled trials comparing valproate to antipsychotics or to placebo (or no intervention), whether as the sole agent or as an adjunct to antipsychotic medication for the treatment of people with schizophrenia or schizophrenia-like psychoses.

DATA COLLECTION AND ANALYSIS

We independently inspected citations and, where possible, abstracts, ordered papers, and re-inspected and quality-assessed these. At least two review authors independently extracted data. We analysed dichotomous data using risk ratio (RR) and its 95% confidence intervals (CI). We analysed continuous data using mean differences (MD) and their 95% CI. We assessed risk of bias for included studies and used GRADE (Grading of Recommendations Assessment, Development and Evaluation) to create a 'Summary of findings' table.

MAIN RESULTS

The 2012 update search identified 19 further relevant studies, most of which were from China. Thus the review currently includes 26 studies with a total of 2184 participants. All trials examined the effectiveness of valproate as an adjunct to antipsychotics. With the exception of two studies, the studies were small, the participants and personnel were not blinded (neither was outcome assessment), and most were short-term and incompletely reported.For this update we prespecified seven main outcomes of interest: clinical response (clinically significant response, aggression/agitation), leaving the study early (acceptability of treatment, overall tolerability), adverse events (sedation, weight gain) and quality of life.Adding valproate to antipsychotic treatment resulted in more clinically significant response than adding placebo to antipsychotic drugs (14 RCTs, n = 1049, RR 1.31, 95% CI 1.16 to 1.47, I2 = 12%, low-quality evidence). However, this effect was removed after excluding open RCTs in a sensitivity analysis. In terms of acceptability of treatment (measured by the number of participants leaving the study early due to any reason) valproate was just as acceptable as placebo (11 RCTs, n = 951, RR 0.76, 95% CI 0.47 to 1.24, I2 = 55%). Also overall tolerability (measured by the number of participants leaving the study early for adverse events) between valproate and placebo was similar (6 RCTs, n = 974, RR 1.33, 95% CI 0.90 to 1.97, I2 = 0).Participants in the valproate group were found to be less aggressive than the control group based on the Modified Overt Aggression Scale (3 RCTs, n = 186, MD -2.55, 95% CI -3.92 to -1.19, I2 = 82%, very low-quality evidence). Participants receiving valproate more frequently experienced sedation (8 RCTs, n = 770, RR 1.38, 95% CI 1.07 to 1.79, I2 = 0, low-quality evidence) but were no more likely to gain weight than those receiving placebo (4 RCTs, n = 427, RR 1.17, 95% CI 0.76 to 1.82, I2 = 0, low-quality evidence). No study reported on the important outcome of quality of life.

AUTHORS' CONCLUSIONS

There is limited evidence, based on a number of trials, that the augmentation of antipsychotics with valproate may be effective for overall clinical response, and also for specific symptoms, especially in terms of excitement and aggression. However, this evidence was entirely based on open RCTs. Moreover, valproate was associated with a number of adverse events among which sedation and dizziness appeared significantly more frequently than in the control groups. Further randomised studies which are blinded are necessary before any clear recommendation can be made. Ideally these would focus on people with schizophrenia and aggression, on those with treatment-resistant forms of the illness and on those with schizoaffective disorders.

Critical review of GABA-ergic drugs in the treatment of schizophrenia

GABA-ergic medications may have a potential role in the treatment of schizophrenia. Laboratory evidence has generally supported the ability of gamma-aminobutyric acid (GABA) to reduce dopaminergic activity and has suggested that GABA may be effective in combating hypofrontality by acting on mesoprefrontocortical tracts in patients resistant to treatment with antipsychotic drugs. Although the results of clinical trials of several GABA-ergic compounds have been inconclusive because of methodologic limitations and drug toxicity, benzodiazepines and valproate seem to be associated with favorable treatment outcomes, especially when combined with typical antipsychotic agents. This study concludes that further investigation of the use of GABA in schizophrenia is likely to improve the understanding of the psychopathology of this illness and to expand our treatment alternatives. Also provided are suggestions to enhance the design of future studies, improve the potential for favorable treatment outcomes, and assist in predicting patients' responses to GABA-ergic medications.

Neuroendocrine dysfunction in psychotic disorders (excluding ACTH)

Neuropeptide and neuroendocrine studies in the two major 'functional' psychotic illnesses have been reviewed. Changes in schizophrenia suggest both central dopamine dysfunction and hypothalamic, and perhaps, limbic pathology. In affective disorders, disruption of rhythmic neuroendocrine control seems to be evident, possibly mediated by either abnormal 5-hydroxytryptamine receptor function, non-specific hypothalamic derangement, or both. It is conceivable that some neuroendocrine changes in depression are trait phenomena which may be markers or mechanisms of vulnerability. The interaction of neuropeptide function and neuroendocrine state in psychotic illness is likely to be the focus of intensive future research.

Baclofen-induced growth hormone secretion is blunted in chronic schizophrenics: neuroendocrine evidence for a GABA disturbance in schizophrenia

To substantiate a previously reported disturbance of gamma-aminobutyric acid (GABA) in chronic schizophrenia, plasma growth hormone (GH) response to a direct GABA agonist (baclofen, 10 mg) was assessed in 12 unmedicated chronic schizophrenic males and 10 sex- and age-matched healthy controls. Baclofen and placebo were administered orally, in a double-blind design, and blood samples were collected before and 30, 60, 90, 120, 180, and 240 min after drug or placebo administration. Baclofen induced a clear-cut rise in plasma GH levels over baseline values, but the GH increase observed in the patients was significantly smaller than that in controls. These results support the idea that GABA mechanisms may be impaired in chronic schizophrenia.

Impaired growth hormone response to sodium valproate in normal aging

Evidence has been provided for impaired neurotransmitter functioning in the brain of elderly subjects. In order to assess central GABAergic transmission, the activity of the hypothalamic GABA system may be investigated by basal growth hormone (GH) response to the GABAergic drug sodium valproate (SV). For this purpose 15 healthy men (aged 19-81 years) received orally 800 mg SV or placebo tablets on two different occasions, 1 week apart. Blood samples were collected before and after drug administration for determining GH and SV plasma levels. A clear-cut increase in plasma GH was observed following SV (P less than 0.001 in young persons, P less than 0.005 in old subjects), but in the aged subjects this rise was statistically lower than in the young men (P less than 0.001 at t = 90 min). No difference was observed in basal GH levels and in SV plasma concentrations between elderly and young subjects. delta GH (= maximum post-SV GH level minus baseline GH value) was significantly inversely related to age (r = -0.90, P less than 0.001). These results may suggest an impaired hypothalamic-pituitary responsiveness to a pharmacological challenge enhancing endogenous GABA tone in the elderly.