Low vitamin D levels are associated with increased negative and depressive symptoms in patients with psychotic disorders, according to findings from a Norwegian study.
Researchers, from the University of Oslo, noted that there had been previous indications that low vitamin D levels are associated with increased disease severity in psychotic disorders.
“The associations… are good arguments for planning large scale randomised controlled studies”
In their studies, the authors investigated if low vitamin D status was linked with a specific symptom profile and if its deficiency affected cognitive deficits in young people with a psychotic disorder.
The studies recruited patients from inpatient and outpatient clinics, and healthy controls. In a first study, the authors included 358 patients with symptoms assessed using the Positive and Negative Syndrome Scale and the Calgary Depression Scale for Schizophrenia.
In a second study, the authors included 225 patients and 159 controls assessed by a battery of cognitive tests looking at processing speed, verbal learning, verbal memory and executive function.
Low vitamin D levels were found to be significantly associated with increased negative and depressive symptoms after controlling for gender differences, education level, inpatient status or having ethnic minority background.
Season of the year for the assessments and having a diagnosis of schizophrenia versus affective psychosis were factored for in the analyses.
The study authors, led by Dr Mari Nerhus, said they were also able to show an association between vitamin D deficiency and cognitive impairments in processing speed and verbal fluency.
Low vitamin D levels linked with psychotic disorders
They suggested that a larger scale trial was needed in order to establish whether vitamin D could have a potential role in the treatment or prevention of psychotic disorders and their symptoms.
“The associations between low vitamin D levels and increased negative and depressive symptoms, and decreased processing speed and verbal fluency are good arguments for planning large scale randomised controlled studies in target populations, in order to reach conclusions about vitamin D’s potential beneficial effect in psychotic disorders,” they said.
The researchers noted that they were currently running studies investigating potential associations between vitamin D levels and brain structures, as measured by magnetic resonance imaging.
The research was presented this week at this year’s International Early Psychosis Association meeting in Milan in Italy.