There is mounting interest in the potential efficacy of low carbohydrate and very low carbohydrate ketogenic diets in various neurological and psychiatric disorders.

To conduct a systematic review and narrative synthesis of low carbohydrate and ketogenic diets (LC/KD) in adults with mood and anxiety disorders.

MEDLINE, Embase, PsycINFO and Cochrane databases were systematically searched for articles from inception to 6 September 2022. Studies that included adults with any mood or anxiety disorder treated with a low carbohydrate or ketogenic intervention, reporting effects on mood or anxiety symptoms were eligible for inclusion. PROSPERO registration CRD42019116367.

The search yielded 1377 articles, of which 48 were assessed for full-text eligibility. Twelve heterogeneous studies (stated as ketogenic interventions, albeit with incomplete carbohydrate reporting and measurements of ketosis; diet duration: 2 weeks to 3 years; n = 389; age range 19 to 75 years) were included in the final analysis. This included nine case reports, two cohort studies and one observational study. Data quality was variable, with no high-quality evidence identified. Efficacy, adverse effects and discontinuation rates were not systematically reported. There was some evidence for efficacy of ketogenic diets in those with bipolar disorder, schizoaffective disorder and possibly unipolar depression/anxiety. Relapse after discontinuation of the diet was reported in some individuals.

Although there is no high-quality evidence of LC/KD efficacy in mood or anxiety disorders, several uncontrolled studies suggest possible beneficial effects. Robust studies are now needed to demonstrate efficacy, to identify clinical groups who may benefit and whether a ketogenic diet (beyond low carbohydrate) is required and to characterise adverse effects and the risk of relapse after diet discontinuation.

We evaluated associations between food insecurity (FI) and the quality and quantity of sleep in adults (≥18 years).

The current study represented a systematic review and meta-analysis of observational studies.

Databases of PubMed, Scopus, Embase and Web of Science were searched from inception until 6 June 2022. Meta-analyses were conducted using random-effects models, and effect sizes were reported as OR and 95 % CI.

Data from ten eligible observational studies, including 83 764 participants, were included.

FI was associated with an increased risk of poor sleep quality (OR = 1·45; 95 % CI (1·24, 1·70), I 2 = 95, P < 0·001, n 7). Besides, subgroup analysis showed increased risk of poor sleep quality corresponding to the severity of FI across mild (OR = 1·31; 95 % CI (1·16, 1·48), I 2 = 0 %, P < 0·001, n 5), moderate (OR = 1·49; 95 % CI (1·32, 1·68), I 2 = 0 %, P < 0·001, n 5) and severe (OR = 1·89; 95 % CI (1·63, 2·20), I 2 = 0 %, P < 0·001, n 5) levels. Similarly, subgroup analysis by sleep problems showed that FI was associated with an increased the risk of trouble falling asleep (OR = 1·39; 95 % CI (1·05, 1·83), I 2 = 91 %, P = 0·002, n 3) and trouble staying asleep (OR = 1·91; 95 % CI (1·37, 2·67), I 2 = 89 %, P < 0·001, n 3). Moreover, FI was associated with the odds of shorter (OR = 1·14; 95 % CI (1·07, 1·21), I 2 = 0 %, P < 0·001, n 4) and longer sleep duration (OR = 1·14; 95 % CI (1·03, 1·26), I 2 = 0 %, P = 0·010, n 4).

Collective evidence supports that FI is associated with poor sleep quality and quantity in adults. Preventative and management strategies that address FI may provide health benefits beyond improving nutritional status per se.

Depression and anxiety are prevalent in youth populations and typically emerge during adolescence. Repetitive negative thinking (RNT) is a putative transdiagnostic mechanism with consistent associations with depression and anxiety. Targeting transdiagnostic processes like RNT for youth depression and anxiety may offer more targeted, personalised and effective treatment.

A meta-analysis was conducted to examine the effect of psychological treatments on RNT, depression and anxiety symptoms in young people with depression or anxiety, and a meta-regression to examine relationships between outcomes.

Twenty-eight randomised controlled trials examining 17 different psychological interventions were included. Effect sizes were small to moderate across all outcomes (Hedge's g depression = −0.47, CI −0.77 to −0.17; anxiety = −0.42, CI −0.65 to −0.20; RNT = −0.45, CI −0.67 to −0.23). RNT-focused and non-RNT focused approaches had comparable effects; however, those focusing on modifying the process of RNT had significantly larger effects on RNT than those focusing on modifying negative thought content. Meta-regression revealed a significant relationship between RNT and depression outcomes only across all intervention types and with both depression and anxiety for RNT focused interventions only.

Consistent with findings in adults, this review provides evidence that reducing RNT with psychological treatment is associated with improvements in depression and anxiety in youth. Targeting RNT specifically may not lead to better outcomes compared to general approaches; however, focusing on modifying the process of RNT may be more effective than targeting content. Further research is needed to determine causal pathways.

There is an increasing focus on lifestyle as a factor in the pathogenesis of mental health disorders; however, this has been relatively underexplored in child populations. This study aimed to assess the relationships between behavioural lifestyle factors and emotional functioning in a large, population-representative sample of schoolchildren in Greece.

A representative sample of 2,240 schoolchildren, aged 9–13 years, participated in the Healthy Growth Study during 2007–2010. Emotional functioning was measured using the Dartmouth COOP Functional Health Assessment charts/World Organization of Family Doctors Charts. A score of 3 or higher out of 5 indicated poorer emotional functioning. Participants self-reported dietary intake via three 24-h dietary recalls; fruit, vegetable and soft drink consumption were the dietary variables of interest. Participants’ self-reported daily time spent in moderate to vigorous physical activity, and watching TV or playing video games were used to assess physical activity and sedentary behaviour.

In fully adjusted models, females were at a greater risk of experiencing impaired emotional functioning compared to males (OR 1.76, 95%CI 1.44, 2.15, p < 0.01). Overweight/obesity compared to normal body weight (OR 1.52, 95%CI 1.31, 1.77, p < 0.01) was associated with poorer emotional functioning. Three hours or more of daily average physical activity compared to less than one hour (OR 0.59, 95%CI 0.40, 0.86, p < 0.01) was associated with improved emotional functioning. Consuming soft drinks compared to non-consumption (OR 1.24, 95%CI 1.02, 1.51) was associated with poorer emotional functioning; this became non-significant after corrections for multiple comparisons were made. Clustering of municipalities was accounted for in all models.

Whilst findings were cross-sectional and causality cannot be inferred, this study highlights the interdependence of emotional and physical functioning in schoolchildren. This points to the potential for targeting shared risk factors for both physical chronic diseases and emotional and mental health conditions among children. Further longitudinal evidence will identify the potential for such shared intervention targets. Adopting a comprehensive, integrated approach to children’s emotional, mental, and physical health is warranted.