Effects of a high-prebiotic diet versus probiotic supplements versus synbiotics on adult mental health : the "gut feelings" randomised controlled trial

Background: Preliminary evidence supports the use of dietary interventions and gut microbiota-targeted interventions such as probiotic or prebiotic supplementation for improving mental health. We report on the first randomised controlled trial (RCT) to examine the effects of a high-prebiotic dietary intervention and probiotic supplements on mental health. Methods: “Gut Feelings” was an 8-week, 2 × 2 factorial RCT of 119 adults with moderate psychological distress and low prebiotic food intake. Treatment arms: (1) probiotic supplement and diet-as-usual (probiotic group); (2) high-prebiotic diet and placebo supplement (prebiotic diet group); (3) probiotic supplement and high-prebiotic diet (synbiotic group); and (4) placebo supplement and diet-as-usual (placebo group). The primary outcome was assessment of total mood disturbance (TMD; Profile of Mood States Short Form) from baseline to 8 weeks. Secondary outcomes included anxiety, depression, stress, sleep, and wellbeing measures. Results: A modified intention-to-treat analysis using linear mixed effects models revealed that the prebiotic diet reduced TMD relative to placebo at 8 weeks [Cohen’s d = −0.60, 95% confidence interval (CI) = −1.18, −0.03; p = 0.039]. There was no evidence of symptom improvement from the probiotic (d = −0.19, 95% CI = −0.75, 0.38; p = 0.51) or synbiotic treatments (d = −0.03, 95% CI = −0.59, 0.53; p = 0.92). Improved anxiety, stress, and sleep were noted in response to the prebiotic diet while the probiotic tentatively improved wellbeing, relative to placebo. No benefit was found in response to the synbiotic intervention. All treatments were well tolerated with few adverse events. Conclusion: A high-prebiotic dietary intervention may improve mood, anxiety, stress, and sleep in adults with moderate psychological distress and low prebiotic intake. A synbiotic combination of high-prebiotic diet and probiotic supplement does not appear to have a beneficial effect on mental health outcomes, though further evidence is required. Results are limited by the relatively small sample size

L-theanine in the adjunctive treatment of generalized anxiety disorder: a double-blind, randomised, placebo-controlled trial

Partial or non-response to antidepressants in Generalized Anxiety Disorder (GAD) is common in clinical settings, and adjunctive biological interventions may be required. Adjunctive herbal and nutraceutical treatments are a novel and promising treatment option. L-theanine is a non-protein amino acid derived most-commonly from tea (Camellia sinensis) leaves, which may be beneficial in the treatment of anxiety and sleep disturbance as suggested by preliminary evidence. We conducted a 10-week study (consisting of an 8-week double-blind placebo-controlled period, and 1-week pre-study and 2-week post-study single-blinded observational periods) involving 46 participants with a DSM-5 diagnosis of GAD. Participants received adjunctive L-theanine (450–900 mg) or matching placebo with their current stable antidepressant treatment, and were assessed on anxiety, sleep quality, and cognition outcomes. Results revealed that adjunctive L-theanine did not outperform placebo for anxiety reduction on the HAMA (p = 0.73) nor insomnia severity on the Insomnia Severity Index (ISI; p = 0.35). However, LT treated participants reported greater self-reported sleep satisfaction than placebo (ISI item 4; p = 0.015). Further, a separation in favour of L-theanine was noted on the ISI in those with non-clinical levels of insomnia symptoms (ISI ≤ 14; p = 0.007). No significant cognitive effects (trail making time and the modified emotional Stroop) were revealed. While this preliminary study did not support the efficacy of L-theanine in the treatment of anxiety symptoms in GAD, further studies to explore the application of L-theanine in sleep disturbance are warranted

Sleep duration CSF biomarkers

Analysis code for the short report publication by Gibson et al (2022): Short sleep duration is associated with lower cerebrospinal fluid amyloid beta levels in midlife: A preliminary report. We investigate the association between total sleep time, measured via actigraphy, and the CSF concentration of biomarkers related to dementia and neurodegeneration

The relationship between dietary quality, serum brain-derived neurotrophic factor (BDNF) level, and the Val66met polymorphism in predicting depression

Background: Brain-derived neurotrophic factor (BDNF), a neurotrophic factor implicated in the pathogenesis of depression, may be influenced by dietary quality. Both dietary quality and serum BDNF have been researched independently in regard to their effect on depression; however, there is limited research investigating the relationship between the two factors and how they interact in depression. Additionally, a single-nucleotide polymorphism (SNP) (Val66Met) in the BDNF gene, which has been implicated in BDNF levels and depression, may contribute to the complex relationship between depression, dietary quality, and BDNF level. Methods: One hundred and eighty-seven participants with major depressive disorder and 55 non-depressed healthy controls were recruited for this case–control analysis. The relationship between dietary quality and depression was assessed via a novel dietary quality score (the Australian Dietary Quality Score). Serum BDNF levels were measured and the Val66Met SNP was genotyped. Results: Healthy controls had a significantly higher diet quality than depressed participants (t = 2.435, P = 0.016). A logistic regression model investigating age, sex, serum BDNF levels, dietary quality and depression, as well as any interactions, found that lower dietary quality, and surprisingly, higher BDNF levels, were associated with increased depression risk, P = 0.037 and P < 0.001, respectively. Neither seasonality (at the time of recruitment) nor the Val66Met polymorphism was associated with BDNF levels in this sample. Furthermore, there was no evidence of interaction between the Val66Met polymorphism, BDNF levels, dietary quality, and depression. Conclusion: Higher dietary quality was associated with both decreased depression incidence and severity in this cross-sectional analysis. The Val66Met polymorphism did not appear to predict BDNF levels, depression incidence, or modify the relationship between dietary quality and BDNF. Further studies utilizing a larger sample size are needed to confirm this finding

Erythrocyte polyunsaturated fatty acid composition is associated with depression and FADS genotype in Caucasians

Background: Polyunsaturated fatty acids (PUFAs) play an important role in the pathophysiology of major depressive disorder (MDD), related, in part, to their role in inflammatory systems. The enzymes δ-5 and δ-6 desaturase are the rate-limiting steps in the metabolism of PUFAs and are encoded in the genes fatty acid desaturase (FADS) 1 and 2, respectively. Single nucleotide polymorphisms (SNPs) and haplotypes within the FADS gene cluster have been shown to influence PUFA composition. Aim: The objective of this study was to determine whether key omega-3 (n-3) and omega-6 (n-6) fatty acids may be associated with depression, and to explore the role of FADS genotype in PUFA variation. Methods: Four erythrocyte long chain (LC) fatty acids (linoleic acid [LA], α-linolenic acid [ALA], arachidonic acid [AA] and Eicosapentaenoic acid [EPA]), as well as six SNPs (rs174537, rs174547, rs174570, rs174575, rs498793 and rs3834458) within the FADS gene cluster were measured in a sample of 207 participants (154 with MDD versus 53 non-depressed controls). Results: The precursor LC-PUFAs LA and ALA appeared to be negatively associated with depression (P < 0.001 and P < 0.01, respectively), while AA:LA (surrogate measure of desaturase activity) was positively associated with depression (P < 0.01). No significant differences were noted in erythrocyte EPA, AA or AA:EPA between groups. Minor alleles of each SNP (excluding rs498793) were associated with variation in desaturase activity and LA. Both rs174537 and rs174547 were associated with ALA. No genotype was associated with EPA or AA. Minor alleles of rs174537 and rs174547 were significantly associated with lower odds of MDD (although significance was lost after correction for multiple comparisons). Conclusion: Precursor LC-PUFAs, LA and ALA, appear to be associated with MDD and potentially modulated by genetic variation in the FADS gene cluster. These results provide support for the consideration of PUFA composition, diet and FADS genetic variation in the pathophysiology of MDD

Nutrient and genetic biomarkers of nutraceutical treatment response in mood and psychotic disorders : a systematic review

Objective: Nutrient and genetic biomarkers in nutraceutical trials may allow for the personalisation of nutraceutical treatment and assist in predicting treatment response. We aimed to synthesise the findings of trials which have included these biomarkers to determine which may be most useful for predicting nutraceutical response in mood and psychotic disorders. Methods: A systematic review was conducted assessing available literature concerning nutraceutical clinical trials in mood and psychotic disorders (major depression, bipolar disorder, schizophrenia) with baseline and endpoint blood nutrient markers or genetic data available. Results: We identified 35 eligible studies (total n = 3836 participants) examining baseline and endpoint nutrient biomarkers and/or genetic polymorphisms. The key result, as reported in 10 out of 11 omega-3 studies, was a strong association between polyunsaturated fatty acid concentrations (mostly EPA and DHA) and psychiatric outcomes, although the exact nature of the association varied between studies and diagnoses. There was no consistent evidence for levels of other nutrients (including Vitamin D, SAM/SAH ratios, carnitine, folate and vitamin B12) relating to treatment response. The evidence for associations between one-carbon cycle genotypes (e.g. MTHFR C677 T, MTR and FOLH1) and treatment response was also inconsistent. Discussion: The available data tentatively supports omega-3 indices as biomarkers of response to omega-3 treatments in mood disorders. Further research with larger samples examining combinations of polymorphisms is required to determine if any genetic factors influence nutraceutical response in mood and psychotic disorders

Sleep regularity and mortality: a prospective analysis in the UK Biobank

Background: Irregular sleep-wake timing may cause circadian disruption leading to several chronic age-related diseases. We examined the relationship between sleep regularity and risk of all-cause, cardiovascular disease (CVD), and cancer mortality in 88,975 participants from the prospective UK Biobank cohort. Methods: The sleep regularity index (SRI) was calculated as the probability of an individual being in the same state (asleep or awake) at any two time points 24 hr apart, averaged over 7 days of accelerometry (range 0–100, with 100 being perfectly regular). The SRI was related to the risk of mortality in time-to-event models. Results: The mean sample age was 62 years (standard deviation [SD], 8), 56% were women, and the median SRI was 60 (SD, 10). There were 3010 deaths during a mean follow-up of 7.1 years. Following adjustments for demographic and clinical variables, we identified a non-linear relationship between the SRI and all-cause mortality hazard (p [global test of spline term]&lt;0.001). Hazard ratios, relative to the median SRI, were 1.53 (95% confidence interval [CI]: 1.41, 1.66) for participants with SRI at the 5th percentile (SRI = 41) and 0.90 (95% CI: 0.81, 1.00) for those with SRI at the 95th percentile (SRI = 75), respectively. Findings for CVD mortality and cancer mortality followed a similar pattern. Conclusions: Irregular sleep-wake patterns are associated with higher mortality risk. Funding: National Health and Medical Research Council of Australia (GTN2009264; GTN1158384), National Institute on Aging (AG062531), Alzheimer’s Association (2018-AARG-591358), and the Banting Fellowship Program (#454104)

Mitochondrial modifying nutrients in treating chronic fatigue syndrome : a 16-week open-label pilot study

Introduction: Recent evidence suggests that mitochondrial dysfunction may play a role in the pathophysiology of chronic fatigue syndrome (CFS). We undertook a pilot investigation of a combination of nutraceutical nutrient compounds which are involved in mitochondrial function and energy generation, to assess their efficacy in improving symptoms of CFS. An open-label design was employed as CFS is largely treatment-resistant with limited placebo-response. Methods: A 16-week open-label trial of a nutraceutical combination (primary nutrients: Coenzyme Q10, Alpha lipoic acid, Acetyl-l-carnitine, N- acetyl cysteine, B Vitamins, in addition to co-factors) was undertaken in ten patients with CFS. Fatigue symptoms, mood and general health were assessed at each 4-week time point over 16 weeks. Of the ten patients (7 female, 3 male) with a mean age of 36.3, eight completed the trial. Results: Linear mixed model analysis demonstrated a significant improvement in fatigue symptoms across treatment period on the Chalder Fatigue Scale (p<0.001). Specific improvements were found in tiredness, weakness, feeling sleepy or drowsy, as well as in sleep, and clinician-reported symptom-improvement. No benefit was observed in mood or other functional domains. No serious adverse events were noted. Conclusion: These preliminary findings suggest that a combination nutraceutical compound of mitochondrial agents may improve CFS symptoms. Further investigation is warranted in a larger double- blind RCT