BackgroundWhile accumulating evidence suggests that vitamin D deficiency may be involved in the risk to develop schizophrenia and its outcome, there are no studies on vitamin D supplementation in this context. We sought to assess the effect of vitamin D supplementation on psychiatric, cognitive and metabolic parameters in chronic clozapine-treated schizophrenia patients.MethodsThis eight-week, randomized, double-blind, placebo-controlled clinical trial, recruited schizophrenia patients who had been maintained on clozapine treatment for at least 18 weeks and had low levels of vitamin D (< 75 nmol/l) and total PANSS scores > 70 (to ascertain the presence of residual symptoms). Patients were randomly allocated to either weekly oral drops of vitamin D (14,000 IU) or placebo and subsequently assessed at two-week intervals for psychosis severity, mood, cognition and metabolic profile.ResultsTwenty four patients were randomly assigned to vitamin D (aged 39.4 ± 9.6 years, 75% males) and the other 23 patients to the placebo arm (aged 42.5 ± 11.2 years, 60.9% males). After eight weeks, the vitamin D group exhibited a significant increase in vitamin D levels (31.4 vs − 0.4 nmol/l, p < 0.0001). There was no significant effect of vitamin D on psychotic, depressive or metabolic parameters. However, in the vitamin D group, there was a trend towards improved cognition (effect size = 0.17, significance lost following Bonferroni correction).ConclusionsVitamin D supplementation was associated with a trend towards improved cognition, but did not affect psychosis, mood or metabolic status. It is possible that the robust decrease in the PANSS scores in both groups may have obscured an effect of vitamin D supplementation.

Our findings suggest that poor adherence to AD is associated with increased all-cause mortality in people with PD. Given the high prevalence of depression and AD effectiveness, efforts to promote adherence should be prioritized in clinical practice.

This article reviews four of the milder but still bothersome side effects of clozapine that are fairly frequent and may have a negative impact on patients' compliance with the treatment regime. We reviewed the available literature on the rate and management of four non-life-threatening side effects of clozapine, including hypersalivation, constipation, tachycardia, and nocturnal enuresis. We found a variety of pharmacological and behavioral strategies to manage these four side effects. There is, however, no consensus on a preferred strategy to control these distressing side effects and there are no guidelines. Psychiatrists should be aware of the relatively high rate of hypersalivation, constipation, tachycardia, and nocturnal enuresis in clozapine-treated patients, of the impact that these side effects may have on patients' quality of life, and should be able to suggest management strategies to the patients.