In amongst my various ramblings about how vitamin D - the sunshine vitamin/hormone - might show more than a few connections to conditions/labels outside of just the English disease (see here), I've covered some science on a possible connection with psychosis (see here) and schizophrenia (see here). There are still gaps in terms of the hows and whys of vitamin D insufficiency and deficiency when it comes to this area of psychiatry, but I believe there is enough science in this area to initially warrant screening of vitamin D levels as and when a diagnosis is received. This similarly extends to other labels too (see here and see here).
The paper by Lally and colleagues  (open-access) puts a little more scientific flesh on the bones about how vitamin D insufficiency/deficiency might manifest in cases of psychosis, with a particular focus on "increased cardiovascular disease risk factors and in particular metabolic syndrome [MetS]."
With thanks to Brendon Stubbs (one of the authors of the paper) for bringing the findings to my attention, researchers set about looking at "the prevalence of vitamin D deficiency in a cohort of community patients with established psychotic illnesses" (N=324). Given my earlier mention of the 'English disease', the cohort were indeed all living in England and drawn from a larger study initiative. Vitamin D levels were assayed via a chemiluminescence immunoassay based on the examination of serum samples. Various other measures were also included for study around the issue of cardiovascular risk factors including body mass index (BMI), waist circumference, blood pressure, serum cholesterol levels and glucose levels. High sensitivity serum C-reactive protein (HS-CRP) was also included.
Results: "Almost half of the sample (48.8 %, n = 158) were deficient in vitamin D while only 13.9 % (n = 45) had sufficient vitamin D." Ethnicity seemed to play a role in those determinations of deficiency/sufficiency with vitamin D levels generally lower in those who were black African or black Caribbean. Likewise the season of testing showed an effect. When it came to determining whether there was an association between vitamin D status and mental state, researchers reported nothing significant based on the use of the Positive And Negative Syndrome Scale (PANSS) and related measures.
But... there might be quite a bit more to look at when taking into account those cardiovascular disease risk factors and vitamin D levels as the authors reported various significant correlations. So: "those with the highest levels of vitamin D have a lower prevalence of MetS (20.5 %), compared to those in the lowest (39.1 %), second (48.3 %) and third quartile (43.1 %) of vitamin D." Indeed, just about every measure of cardiovascular risk showed an association with measured serum vitamin D levels when controlling for "age, gender, ethnicity and season of 25-OHD blood sampling." The authors also add that: "Those engaging in low intensity physical activity over the week prior to sampling... had significantly lower 25-OHD levels... than those who engaged in moderate or high intensity physical activity."
Teasing apart what might actually be doing what is a difficult task in such studies where various outcome measures might be implicated. The authors do speculate on how for example, their finding of "raised CRP and vitamin D deficiency in established psychosis" might tie into other research on inflammation or inflammatory processes with both variables in mind (see here and see here). Indeed, this might also tie in with calls for further integration of immunopsychiatry with psychotic disorders in mind . But there remains more to do, including the intriguing question: "would the supplementation of vitamin D in psychosis prevent and/or ameliorate cardiovascular and metabolic risk?"
I do have some small points to make about the study that might also require attention in follow-up work, not least the idea that immunoassay for determining functional vitamin D levels might not be the most accurate method . Indeed, the authors make this point in their conclusions. One might also hope that comparisons with other patient groups might offer some further information about how specific the findings are to just psychosis or other psychiatric groupings. If found in a more general sense, the idea that vitamin D is related to variables affecting cardiovascular risk in such groups could make lots and lots of waves.
For now however, this research extends the ideas that: (a) preferential screening for vitamin D might be indicated for this group/label, and (b) the focus on psychiatric presentation should not be made at the expense of somatic presentation. Parity of esteem and all that; or rather just making sure that health inequality does not follow from receipt of a psychiatric label...
 Lally J. et al. Clinical correlates of vitamin D deficiency in established psychosis. BMC Psychiatry. 2016; 16: 76.
 Leboyer M. et al. Is it time for immunopsychiatry in psychotic disorders? Psychopharmacology (Berl). 2016 Mar 18.
 Yang Y. et al. High-throughput measurement of 25-hydroxyvitamin D by LC-MS/MS with separation of the C3-epimer interference for pediatric populations. Clin Chim Acta. 2016 Feb 15;454:102-6.
Lally, J., Gardner-Sood, P., Firdosi, M., Iyegbe, C., Stubbs, B., Greenwood, K., Murray, R., Smith, S., Howes, O., & Gaughran, F. (2016). Clinical correlates of vitamin D deficiency in established psychosis BMC Psychiatry, 16 (1) DOI: 10.1186/s12888-016-0780-2