Circulating levels of vitamin D, vitamin B12, folate, homocysteine, and major haemato-chemical parameters in mood-disorder patients: a comparative cross-sectional study

The potential involvement of the immune and inflammatory systems, together alterations of their biochemical markers, has been extensively studied in mood disorders such as major depression and bipolar disorders. This topic in clinical research is currently providing important results. Indeed, an ever-growing body of evidence is showing the presence, within patients, of activated inflammatory patterns resulting from altered neurotransmission and abnormally regulated neuroendocrine response to stress; bidirectionally, inflammatory patterns have been found to provoke impaired neurotransmission, stress coping and metabo-lism in mood disorders. Moreover, several clinical surveys have reported that plasma levels of some pro-inflammatory cytokines and acute phase proteins can vary depending on the phases of these disorders. As well, patients have been found to display disrupted redox systems and nutritional status. Despite these findings and despite the fact that the pathogenetic role of altered immu-nologic and metabolic profiles in mood disorders is being confirmed in many current studies, there is still a general lack of consensus about it, due to results that do not always agree. This implies the need to extend previous investiga-tions. In such a context, the present study aimed to appraise peripheral metabolic pa-rameters and plasma/serum levels of essential nutrients in a group of inpa-tients affected by mood disorders for comparison with the same biological in-dexes measured in a control sample. Specifically, the study compared, in these two groups, blood glucose, lipoproteins, triglycerides, uric acid, blood urea ni-trogen (BUN), transaminases and other haemato-chemical parameters, to-gether the plasma/serum levels of some vitamins (vitamin D, B12, folate) and homocysteine, a key substrate of methionine metabolism which is involved in crucial pleiotropic enzyme reactions in the body. Results showed that most pa-tients, despite their heterogeneity in diagnosis and clinical presentation, were highly defective in circulating vitamin D levels, not only in respect to control subjects (P< .0001) but even in respect to the general population normative cut-off values. This vitamin D result was paralleled by strongly increased serum homocysteine concentrations in patients vs. controls (P<.0001), indicating an imbalance in their methionine metabolism, a finding suggesting the impairment at the level of methylation patterns and redox regulatory fluxes in affected sub-jects. Surprisingly, homocysteine levels were negatively correlated with vitamin D, vitamin B12 and folate values in control subjects but not in patients, sug-gesting that changes of methionine metabolism and vitamin deficits were oc-curring independently in patients. In addition, patients displayed higher blood glucose and lower BUN than controls, indicating an impaired protein-to-carbohydrate metabolism and/or altered nutritional/dietary status, such as the preferential assumption of carbohydrates rather than proteins. Briefly, we pro-vide herein further substantiation to the idea that mood disorder patients are a population where vitamin deficits, dysmetabolism and/or dietary defects are very common features. As a corollary, we want to emphasize herein that peo-ple affected by major depressive disorder (MDD) or bipolar disorders (BDs) are exposed to a greater risk of a variety of somatic illnesses than the general pop-ulation. In summary, this cross-sectional investigation, albeit preliminary, contributes to improve the characterization and the monitoring of the clinical status of mood disorder patients. Our results are the starting point to the identification of new molecular targets for more tailored treatments, as well as to the im-plementation of more pointed health-care interventions, such as nutritional measures and the co-administration of essential substrates with psychotropic drugs and/or psychological therapies.