It has been suggested that people with mental disorders have an elevated risk to acquire severe acute respiratory syndrome coronavirus 2 and to be disproportionally affected by coronavirus disease 19 (COVID-19) once infected. We aimed to analyse the COVID-19 infection rate, course and outcome, including mortality and long COVID, in people with anxiety, depressive, neurodevelopmental, schizophrenia spectrum and substance use disorders relative to control subjects without these disorders.

This study constitutes a preregistered systematic review and random-effects frequentist and Bayesian meta-analyses. Major databases were searched up until 27 June 2023.

Eighty-one original articles were included reporting 304 cross-sectional and prospective effect size estimates (median n per effect-size = 114837) regarding associations of interest. Infection risk was not significantly increased for any mental disorder that we investigated relative to samples of people without these disorders. The course of COVID-19, however, is relatively severe, and long COVID and COVID-19-related hospitalization are more likely in all patient samples that we investigated. The odds of dying from COVID-19 were high in people with most types of mental disorders, except for those with anxiety and neurodevelopmental disorders relative to non-patient samples (pooled ORs range, 1.26–2.57). Bayesian analyses confirmed the findings from the frequentist approach and complemented them with estimates of the strength of evidence.

Once infected, people with pre-existing mental disorders are at an elevated risk for a severe COVID-19 course and outcome, including long COVID and mortality, relative to people without pre-existing mental disorders, despite an infection risk not significantly increased.

People with neurodegenerative disease and mild cognitive impairment (MCI) may have an elevated risk of acquiring severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and may be disproportionally affected by coronavirus disease 2019 (COVID-19) once infected.

To review all eligible studies and quantify the strength of associations between various pre-existing neurodegenerative disorders and both SARS-CoV-2 susceptibility and COVID-19 illness course and outcome.

Pre-registered systematic review with frequentist and Bayesian meta-analyses. Systematic searches were executed in PubMed, Web of Science and preprint servers. The final search date was 9 January 2023. Odds ratios (ORs) were used as measures of effect.

In total, 136 primary studies (total sample size n = 97 643 494), reporting on 268 effect-size estimates, met the inclusion criteria. The odds for a positive SARS-CoV-2 test result were increased for people with pre-existing dementia (OR = 1.83, 95% CI 1.16–2.87), Alzheimer's disease (OR = 2.86, 95% CI 1.44–5.66) and Parkinson's disease (OR = 1.65, 95% CI 1.34–2.04). People with pre-existing dementia were more likely to experience a relatively severe COVID-19 course, once infected (OR = 1.43, 95% CI 1.00–2.03). People with pre-existing dementia or Alzheimer's disease were at increased risk for COVID-19-related hospital admission (pooled OR range: 1.60–3.72). Intensive care unit admission rates were relatively low for people with dementia (OR = 0.54, 95% CI 0.40–0.74). All neurodegenerative disorders, including MCI, were at higher risk for COVID-19-related mortality (pooled OR range: 1.56–2.27).

Our findings confirm that, in general, people with neurodegenerative disease and MCI are at a disproportionally high risk of contracting COVID-19 and have a poor outcome once infected.

The number of forced migrants is increasing worldwide. Some governments detain refugees and migrants in immigration detention centres, which is associated with adverse mental health outcomes.

To estimate prevalence rates of depression, anxiety and post-traumatic stress disorder (PTSD) in child and adult refugees and migrants in immigration detention.

Pre-registered systematic review with meta-analysis (Prospero ID: CRD42020196078).

Systematic searches in Medline, Embase and Web of Science (final search date 1 October 2020) yielded nine eligible studies on the mental health of detained refugees and migrants (total n = 630 refugees and migrants, 522 of them in detention, among which 26 were children). For adults, prevalence rates for depression were 68% (95% CI 0.53–0.83%), for anxiety 54% (95% CI 0.36–0.72%) and for PTSD 42% (95% CI 0.22–0.63%). Theoretical comparisons with data from other meta-analyses revealed that prevalence rates and symptom severity were higher in detained, relative to non-detained samples.

Our data show a huge burden of mental health problems in detained refugees and migrants of all ages, also relative to non-detained samples. This suggests that immigration detention independently and adversely affects the mental health of refugees and migrants. This insight should encourage countries to minimise the use of immigration detention and implement alternative measures instead.

The number of refugees is at its highest since the Second World War and on the rise. Many refugees suffer from anxiety, depression and post-traumatic stress disorder (PTSD), but exact and up-to-date prevalence estimates are not available.

To report the pooled prevalence of anxiety and mood disorders and PTSD in general refugee populations residing in high-income countries and to detect sources of heterogeneity therein.

Systematic review with meta-analyses and meta-regression.

Systematic searches (final search date 3 August 2019) yielded 66 eligible publications that reported 150 prevalence estimates (total sample N = 14 882). Prevalence rates were 13 and 42% (95% CI 8–52%) for diagnosed and self-reported anxiety, 30 and 40% (95% CI 23–48%) for diagnosed and self-reported depression, and 29 and 37% (95% CI 22–45%) for diagnosed and self-reported PTSD. These estimates are substantially higher relative to those reported in non-refugee populations over the globe and to populations living in conflict or war settings, both for child/adolescent and adult refugees. Estimates were similar over different home and resettlement areas and independent of length of residence.

Our data indicate a challenging and persisting disease burden in refugees due to anxiety, mood disorders and PTSD. Knowing this is relevant for the development of public health policies of host countries. Scalable interventions, tailored for refugees, should become more readily available.

Magnesium (Mg2+) has received considerable attention with regards to its potential role in the pathophysiology of the mood disorders, but the available evidence seems inconclusive.

To review and quantitatively summarise the human literature on Mg2+ intake and Mg2+ blood levels in the mood disorders and the effects of Mg2+ supplements on mood.

Systematic review and meta-analyses.

Adherence to a Mg2+-rich diet was negatively associated with depression in cross-sectional (odds ratio = 0.66) but not in prospective studies. Mg2+ levels in bodily fluids were on average higher in patients with a mood disorder (Hedge's g = 0.19), but only in patients treated with antidepressants and/or mood stabilisers. There was no evident association between Mg2+ levels and symptom severity. Mg2+ supplementation was associated with a decline in depressive symptoms in uncontrolled (g = −1.60) but not in placebo-controlled trials (g = −0.21).

Our results provide little evidence for the involvement of Mg2+ in the mood disorders.

None.