Plasma pterins and folate in late life depression: the Rotterdam Study

Peripheral biopterin and neopterin in schizophrenia and depression

Increasing evidence points to a causal involvement of inflammation in the pathogenesis of neuropsychiatric disorders, including major depressive disorder (MDD) and schizophrenia (SZ). Neopterin and biopterin may link peripheral immune system activation and central neurotransmitter alterations. However, it is not fully established whether these alterations are transdiagnostic or disorder-specific and whether they are associated with reward-related psychopathologies. We investigated group differences in neopterin and biopterin in the plasma of healthy comparison (HC) (n=19), SZ (n=45) and MDD (n=43) participants. We then correlated plasma proteins with CRP as a measure for inflammation. Lastly, plasma proteins were correlated with the reward-related psychopathological domain apathy. We found a trend-level difference in biopterin levels and no significant difference in neopterin levels between groups. Within both patient groups, but not HC, we show a significant positive correlation of CRP with neopterin but not with biopterin. Further, we observed no significant correlations of plasma proteins with reward-related psychopathology in HC, MDD or SZ. While our study shows trend-level alterations of biopterin with relevance for future research, it does not support the hypothesis that peripheral neopterin or biopterin are associated with reward-related psychopathology.

The association of folate and depression: A meta-analysis

BACKGROUND

Previous research suggested that folate levels play an important role in the etiology and course of depression. However, the literature has been inconsistent with regard to differences in folate level between individuals with and without depression. The present meta-analysis synthesized the results of previous studies to examine whether individuals with depression had lower levels of folate than individuals without depression.

METHODS

Meta-analytic procedures were conducted in accordance with PRISMA guidelines. Studies evaluating folate levels in individuals with and without depression via red blood cell folate, serum folate, or dietary intake of folate methods were identified via PsycINFO and PubMed. Random-effects meta-analysis was conducted using Hedge's g, and moderation analysis was used for both folate measurement method and population type. Study heterogeneity was assessed with I² and publication bias was qualitatively assessed via funnel plot and quantitatively assessed with the trim-and-fill method and Begg's adjusted rank test.

RESULTS

We found a significant, small effect size, such that individuals with depression had lower folate levels than those without depression, Hedge's g = -0.24 (95% CI = -0.31, -0.16), p < 0.001. Study heterogeneity was high (I² = 84.88%), and neither folate measurement method nor population accounted for study heterogeneity.

CONCLUSIONS

Individuals with depression have lower serum levels of folate and dietary folate intake than individuals without depression. Given that previous literature suggested folate supplementation improved the efficacy of traditional antidepressant medications, future research on folate supplementation in depression is warranted and clinicians may wish to consider folate supplementation for patients with depression.

Folate and B12 serum levels in association with depression in the aged: a systematic review and meta-analysis

OBJECTIVES

To systematically review and meta-analyse existing evidence on the association between folate/B12, and depression among the aged people.

METHODS

Following PRISMA/STROBE guidelines, the Medline abstracts were retrieved using an algorithm comprising relevant MeSH terms. Publications on the association of folate/B12 serum measurements with depression were abstracted independently by two reviewers and included in both gender and gender-specific meta-analyses, following recarculations of published data as appropriate. The Newcastle-Ottawa scale was used to evaluate the quality of included studies.

RESULTS

Both gender data were contributed by 11 folate-related (7949 individuals) and 9 B12-related studies (6308 individuals), whereas gender-specific data by 4 folate-related (3409 individuals) and 3 B12-related studies (1934 individuals). A statistically significant overall association between both exposures of interest (low folate and B12 levels) and depression was observed (ORfolate:1.23, 95%CI:1.07-1.43, ORB12:1.20, 95%CI:1.02-1.42). Gender-specific estimates pointed to a statistically significant positive association between low B12 levels and depression only among women (OR:1.33, 95%CI:1.02-1.74); the gender specific associations of low folate levels with depression were, however, non-significant and of counter-direction (ORfemales:1.37, 95%CI:0.90-2.07; ORmales:0.84, 95%CI:0.57-1.25).

CONCLUSION

Low folate and B12 serum levels seem to be associated with depression in the aged. The gender-specific analyses are confined to a positive association of low B12 with depression among older women and call for further research in this direction.

Elevated Serum Levels of Neopterin at Admission Predicts Depression After Acute Ischemic Stroke: a 6-Month Follow-Up Study

Inflammation and cell-mediated immune activation are attributed to the pathogenesis and pathophysiology in depression. Our aim was to test the possible association between serum levels of neopterin and the development of post-stroke depression (PSD) in Chinese patients. The subjects were first-ever acute ischemic stroke patients who were hospitalized at the First Affiliated Hospital of Xinxiang Medical University during the period from December 2012 to December 2013. Clinical information and stroke severity were collected at admission. Neurological and neuropsychological evaluations were conducted at the 6-month follow-up. Serum neopterin levels were measured using fluorometry and a high performance liquid chromatography (HPLC) method. Multivariate analyses were performed using logistic regression models. During the study period, 226 patients were included and finished the 6-month follow-up. Sixty-nine patients (30.5 %) were diagnosed as having major depression at 6 months. Patients with major depression showed higher levels of serum neopterin (21.6[IQR, 18.9-25.7]nmol/L vs. 14.6[IQR, 12.2-18.4]nmol/L, P < 0.0001) at admission. In multivariate analyses, serum neopterin was an independent predictor of PSD at 6 months [odds ratio (OR): 1.952 (95 % CI, 1.358-2.805), P < 0.0001]. With an AUC of 0.850 (95 % CI, 0.797-0.902), neopterin showed a significantly greater discriminatory ability as compared with high-sensitivity C-reactive protein, age, body mass index, and National Institutes of Health and Stroke Scale score. Neopterin is a novel, independent predictor of the development of depression 6 months after stroke. This indicated that the elevated neopterin levels may play a significant role in the pathology of depression and that the pathways leading to inflammation and cell-mediated immune activation warrant further exploration.

Anxiety- and depression-like phenotype of hph-1 mice deficient in tetrahydrobiopterin

Decreased tetrahydrobiopterin (BH4) biosynthesis has been implicated in the pathophysiology of anxiety and depression. The aim of this study was therefore to characterise the phenotype of homozygous hph-1 (hph) mice, a model of BH4 deficiency, in behavioural tests of anxiety and depression as well as determine hippocampal monoamine and plasma nitric oxide levels. In the elevated zero maze test, hph mice displayed increased anxiety-like responses compared to wild-type mice, while the marble burying test revealed decreased anxiety-like behaviour. This was particularly observed in male mice. In the tail suspension test, hph mice of both sexes displayed increased depression-like behaviours compared to wild-type counterparts, whereas the forced swim test showed a trend towards increased depression-like behaviours in male hph mice, but significant decrease in depression-like behaviours in female mice. This study provides the first evidence that congenital BH4 deficiency regulates anxiety- and depression-like behaviours. The altered responses observed possibly reflect decreased hippocampal serotonin and dopamine found in hph mice compared to wild-type mice, but also reduced nitric oxide formation. We propose that the hph-1 mouse may be a novel tool to investigate the role of BH4 deficiency in anxiety and depression.

Tryptophan: the key to boosting brain serotonin synthesis in depressive illness

It has been proposed that focusing on brain serotonin synthesis can advance antidepressant drug development. Biochemical aspects of the serotonin deficiency in major depressive disorder (MDD) are discussed here in detail. The deficiency is caused by a decreased availability of the serotonin precursor tryptophan (Trp) to the brain. This decrease is caused by accelerated Trp degradation, most likely induced by enhancement of the hepatic enzyme tryptophan 2,3-dioxygenase (TDO) by glucocorticoids and/or catecholamines. Induction of the extrahepatic Trp-degrading enzyme indolylamine 2,3-dioxygenase (IDO) by the modest immune activation in MDD has not been demonstrated and, if it occurs, is unlikely to make a significant contribution. Liver TDO appears to be a target of many antidepressants, the mood stabilisers Li(+) and carbamazepine and possibly other adjuncts to antidepressant therapy. The poor, variable and modest antidepressant efficacy of Trp is due to accelerated hepatic Trp degradation, and efficacy can be restored or enhanced by combination with antidepressants or other existing or new TDO inhibitors. Enhancing Trp availability to the brain is thus the key to normalisation of serotonin synthesis and could form the basis for future antidepressant drug development.

Serum folate, vitamin B-12, and homocysteine and their association with depressive symptoms among U.S. adults

OBJECTIVE

To examine, in a nationally representative sample of U.S. adults, the associations of serum folate, vitamin B-12, and total homocysteine (tHcy) levels with depressive symptoms. Several nutritional and physiological factors have been linked to depression in adults, including low folate and vitamin B-12 and elevated tHcy levels.

METHODS

Data on U.S. adults (age, 20-85 years; n = 2524) from the National Health and Nutrition Examination Survey during the period 2005 to 2006 were used. Depressive symptoms were measured with the Patient Health Questionnaire (PHQ), and elevated symptoms were defined as a PHQ total score of ≥10. Serum folate, vitamin B-12, and tHcy were mainly expressed as tertiles. Multiple ordinary least square (OLS), logistic, and zero-inflated Poisson regression models were conducted in the main analysis.

RESULTS

Overall, mean PHQ score was significantly higher among women compared with men. Elevated depressive symptoms (PHQ score of ≥10) were inversely associated with folate status, particularly among women (fully adjusted odds ratio [tertiles T(3) versus T(1)] = 0.37; 95% confidence interval, 0.17-0.86), but not significantly related to tHcy or vitamin B-12. No interaction was noted between the three exposures in affecting depressive symptoms. In older adults (≥50 years) and both sexes combined, tHcy was positively associated with elevated depressive symptoms (fully adjusted odds ratio [tertiles T(2) versus T(1)] = 3.01; 95% confidence interval, 1.01-9.03), although no significant dose-response relationship was found.

CONCLUSIONS

Future interventions to improve mental health outcomes among U.S. adults should take into account dietary and other factors that would increase levels of serum folate.

The association between serum levels of neopterin and number of depressive episodes of major depression

BACKGROUND

There is an interaction between the immune system and the central nervous system by means of hormones, peptides, and neurotransmitters. The aims of the present study were to determine whether the serum neopterin levels in patients with major depression (MD) differ from a healthy control group and to investigate the relationship between previous MD episodes and serum neopterin levels.

METHODS

Thirty patients who were admitted to the GATA Psychiatry Outpatient Clinics and were diagnosed with MD according to DSM-IV, and who agreed to participate in the study, were included in the study. Twenty-six healthy volunteers matched for age, gender, and level of education who agreed to participate in the study were served as controls. Peripheral venous blood samples were obtained from the patients and the control group for complete blood count, routine biochemistry, and the detection of serum neopterin levels. The analyses were performed in the laboratory of the GATA Department of Biochemistry.

RESULTS

There was no significant difference between the MD group and the healthy controls with respect to age, level of education, smoking, and gender. Serum neopterin levels of the MD group who had experienced two or more episodes were higher than the first-episode group and the control group. Age of onset and the number of previous episodes had an independent impact on serum neopterin levels in MD patients, while smoking did not show any effect.

CONCLUSION

In the present study, the neopterin levels of patients who had experienced two or more episodes were higher than the first-episode depressive group and healthy control group. It was also found that the number of previous depressive episodes and the ages of the MD cases had an independent effect on serum neopterin levels.

An enzymatic method to distinguish tetrahydrobiopterin from oxidized biopterins using UDP-glucose:tetrahydrobiopterin glucosyltransferase

The quantitative determination of tetrahydrobiopterin (BH4) and its oxidized forms (dihydrobiopterin and biopterin) is important in searching for possible markers of neuropsychiatric and cardiovascular disorders as well as in diagnosing BH4 deficiencies. Currently, two high-performance liquid chromatography (HPLC) methods are available, although both have some limitations. We developed an enzymatic method to distinguish BH4 from the oxidized forms by employing BH4:UDP-glucose alpha-glucosyltransferase (BGluT), which catalyzes glucosyl transfer from UDP-glucose to BH4. The recombinant BGluT isolated from Escherichia coli converted essentially all of the BH4 in a mixture containing oxidized biopterins to the glucoside while leaving the oxidized forms intact. Therefore, acidic iodine oxidation of the reaction mixture followed by single fluorescence HPLC permitted the determination of biopterin and biopterin-glucoside, which represent oxidized biopterins and BH4, respectively. The validity of the method was evaluated using authentic biopterins and animal samples such as human urine, rat plasma, and rat liver. The BGluT-catalyzed reaction not only would reduce the burden of chromatographic separation but also would promise non-HPLC analysis of BH4.

The sex-specific role of plasma folate in mediating the association of dietary quality with depressive symptoms

Folate deficiency has been implicated in the etiology of unipolar depression. In this study, we attempted to cross-link plasma folate, depressive symptoms, and dietary quality (or dietary intake of folate) together in a comprehensive framework, while examining effect modification of those associations by sex. This was a cross-sectional, population-based study of 1681 participants aged 30-64 y (Healthy Aging in Neighborhoods of Diversity across the Lifespan Study). Participants were administered the Center for Epidemiologic Studies Depression scale (CES-D). Measures of plasma folate and dietary intakes (2 24-h recalls) from which the 2005-Healthy Eating Index (HEI) was computed were available. Multivariate logistic regression and structural equation modeling (SM) were conducted. Compared with the lowest tertile, the middle and uppermost tertiles of plasma folate were associated with a 39-40% reduced odds of elevated CES-D (> or =16) among women [adjusted odds ratio (T(3) vs. T(1)) = 0.60 (95% CI = 0.42-0.86); P = 0.006]. Confounding of this association by HEI(total) was noted among both men and women, although dietary folate did not confound this association appreciably. In SM, plasma folate completely mediated the inverse HEI(total)-CES-D association among men only, specifically for HEI(2) (higher intakes of whole fruits), HEI(3) (total vegetables), HEI(5) (total grains), HEI(6) (whole grains), HEI(7) (milk), and HEI(12) (lower discretionary energy). Among women, HEI(total) and 4 components had an inverse direct effect on CES-D score, suggesting a mechanism that is independent of plasma folate. Depressive symptoms in our study may be alleviated by improving overall dietary quality, with plasma folate playing a potential mediating role only among men.

Polymorphisms of sepiapterin reductase gene alter promoter activity and may influence risk of bipolar disorder

OBJECTIVES

In a previous investigation, we observed altered expression of sepiapterin reductase (SPR) in cultured neural cells chronically exposed to paroxetine. SPR is an enzyme, which catalyzes the final step in the synthesis of tetrahydrobiopterin (BH4). BH4 is an essential cofactor for synthesis of many neurotransmitters including serotonin. Given the pivotal role of SPR in neurotransmitter production, we sought to test the hypothesis that SPR would influence susceptibility to mood disorders and patient response to antidepressants.

METHODS

We tested for association of SPR promoter polymorphisms with antidepressant response in a well-characterized triad cohort of mood disorders. We evaluated the functional effect of these variants using the Dual-Luciferase Reporter Gene Assay System in two independent cell lines.

RESULTS

Two promoter single nucleotide polymorphisms (rs1876487 and rs2421095) in SPR were identified that occurred in three distinct haplotypes. We found a statistically significant association of haplotype pair 2,3 with bipolar I disorder [odds ratio: 5.47; 95% confidence interval: (1.68-17.88); P<0.005] and the personality measure self-transcendence (P = 0.020). Moreover, we found preliminary evidence that individuals with haplotype pair 2,3 responded better to the treatment with selective serotonin reuptake inhibitors. Reporter gene assays revealed a 1.4-fold to 1.6-fold decrease in the transcription rate of the two less common haplotypes (2 and 3) compared with haplotype 1, in the two cell lines investigated.

CONCLUSION

This reduced transcription rate for SPR promoter haplotypes 2 and 3 may impact on BH4-mediated neurotransmitter production, thus suggesting a biological process through which SPR gene variants might influence antidepressant response and susceptibility to bipolar disorder.

Collaborative depression care, screening, diagnosis and specificity of depression treatments in the primary care setting

The identification, referral and specific treatment of midlife patients in primary care who are distressed by mood, anxiety, sleep and stress-related symptoms, with or without clinically confirmed menopausal symptoms, are confounded by many structural issues in the delivery of women's healthcare. Diagnosis, care delivery, affordability of treatment, time commitment for treatment, treatment specificity for a particular patient's symptoms and patient receptiveness to diagnosis and treatment all play roles in the successful amelioration of symptoms in this patient population. The value of screening for depression in primary care, the limitations of commonly used screening instruments relative to culture and ethnicity, and which clinical care systems make best use of diagnostic screening programs will be discussed in the context of the midlife woman. The Sequenced Treatment Alternatives to Relieve Depression (STAR*D) program illustrates the relatively high rate of unremitted patients, regardless of clinical setting, who are receiving antidepressants. Nonmedication treatment approaches, referred to in the literature as 'nonsomatic treatments', for depression, anxiety and stress, include different forms of cognitive-behavioral therapy, interpersonal therapy, structured daily activities, mindfulness therapies, relaxation treatment protocols and exercise. The specificity of these treatments, their mechanisms of action, the motivation and time commitment required of patients, and the availability of trained practitioners to deliver them are reviewed. Midlife women with menopausal symptoms and depression/anxiety comorbidity represent a challenging patient population for whom an individualized treatment plan is often necessary. Treatment for depression comorbid with distressing menopausal symptoms would be facilitated by the implementation of a collaborative care program for depression in the primary care setting.

Theoretical Study on the Singlet Excited State of Pterin and Its Deactivation Pathway

The excited-state properties and related photophysical processes of the acidic and basic forms of pterin have been investigated by the density functional theory and ab initio methodologies. The solvent effects on the low-lying states have been estimated by the polarized continuum model and combined QM/MM calculations. Calculations reveal that the observed two strong absorptions arise from the strong pi --> pi* transitions to 1(pipi*L(a)) and 1(pipi*L(b)) in the acidic and basic forms of pterin. The first 1(pipi*L(a)) excited state is exclusively responsible for the experimental emission band. The vertical 1(n(N)pi*) state with a small oscillator strength, slightly higher in energy than the 1(pipi*L(a)) state, is less accessible by the direct electronic transition. The 1(n(N)pi*) state may be involved in the photophysical process of the excited pterin via the 1(pipi*L(a)/n(N)pi*) conical intersection. The radiationless decay of the excited PT to the ground state experiences a barrier of 13.8 kcal/mol for the acidic form to reach the (S(1)/S(0)) conical intersection. Such internal conversion can be enhanced with the increase in excitation energy, which will reduce the fluorescence intensity as observed experimentally.