Vitamin D, a steroid hormone that helps to regulate calcium metabolism and immune function, may also play a role in neurological and psychiatric disorders
The 1-alpha-hydroxylase enzyme, which activates vitamin D, as well as vitamin D receptors have been identified in the neurons and glial cells of the central nervous system.
Animal studies have shown vitamin D deficiency to produce anatomic changes in brain development, and human studies suggest that vitamin D supplementation may benefit some psychiatric illnesses, such as major depression and Alzheimer’s disease.
Schizophrenia has been correlated with vitamin D deficiency during the prenatal period and early childhood, but only limited research has been conducted on the relationship between symptom severity and vitamin D levels in schizophrenia.
To determine whether vitamin D levels differ between individuals with schizophrenia and those without, and to determine if vitamin D status influences symptom severity, researchers at a teaching and research hospital in Turkey conducted a case control study.
The study included 80 adult patients with schizophrenia and 74 controls. All participants were evaluated with the Scale for Assessment of Negative Symptoms (SANS), which includes affective blunting, apathy and asociality, and the Scale for Assessment of Positive Symptoms (SAPS), which includes hallucinations, delusions and bizarre behaviour. Participants were also evaluated for serum 25(OH)D levels.
Results showed that mean serum vitamin D levels were similar in patients with schizophrenia and controls (both groups had mean serum levels of 23–24ng/mL). When patients with schizophrenia were grouped according to vitamin D levels, however, significant differences were observed in symptom severity.
Compared with sufficient vitamin D levels (>20ng/mL), patients with deficient levels (>10ng/mL) demonstrated significantly higher total SANS, total SAPS, and subscores in affective flattening, bizarre behaviour, and positive formal thought disorder (all p<0.01).
Serum vitamin D levels were inversely correlated with SANS points, attention points, and positive formal thoughts.
These results demonstrate increased severity of symptoms at lower vitamin D levels in patients with schizophrenia. Researchers suggest that patients with schizophrenia be routinely evaluated and treated for vitamin D insufficiency.