Converging global evidence highlights the dire consequences of climate change for human mental health and wellbeing. This paper summarises literature across relevant disciplines to provide a comprehensive narrative review of the multiple pathways through which climate change interacts with mental health and wellbeing. Climate change acts as a risk amplifier by disrupting the conditions known to support good mental health, including socioeconomic, cultural and environmental conditions, and living and working conditions. The disruptive influence of rising global temperatures and extreme weather events, such as experiencing a heatwave or water insecurity, compounds existing stressors experienced by individuals and communities. This has deleterious effects on people’s mental health and is particularly acute for those groups already disadvantaged within and across countries. Awareness and experiences of escalating climate threats and climate inaction can generate understandable psychological distress; though strong emotional responses can also motivate climate action. We highlight opportunities to support individuals and communities to cope with and act on climate change. Consideration of the multiple and interconnected pathways of climate impacts and their influence on mental health determinants must inform evidence-based interventions. Appropriate action that centres climate justice can reduce the current and future mental health burden, while simultaneously improving the conditions that nurture wellbeing and equality. The presented evidence adds further weight to the need for decisive climate action by decision makers across all scales.

This systematic review provides a comprehensive synthesis of recent epidemiological evidence that environmental noise negatively impacts human cognition. We update a prior review with recent publications (PROSPERO CRD42019151923). The strength of evidence for associations was assessed using the GRADE (Grading of Recommendations, Assessment, Development and Evaluations) framework. We also conducted random-effects meta-analyses where suitable. 16 studies were identified and reviewed in tandem with 32 studies previously reviewed by Clark & Paunovic (2018). A meta-analysis from 3 studies found that reading comprehension scores in quiet classrooms were 0.80 (95% confidence interval: 0.40; 1.20) points higher than children in noisier classrooms. Meta-analysis of the impact of 1 dB (dB) increase in environmental noise on reading and language abilities gave a pooled beta coefficient of -0.11(95% confidence interval: -0.32; 0.10). A meta-analysis of Odds Ratios (OR) from 3 studies found higher odds of cognitive impairment in people aged 45 + with higher residential noise exposure (OR 1.40, 95% CI: 1.18;1.61). After qualitative synthesis of remaining studies, there was high quality evidence for an association between environmental noise and cognitive impairment in middle-to-older adults, moderate quality evidence for an association between aircraft noise and reading and language in children, and moderate quality evidence against an association between aircraft noise and executive functioning in children. Generally the literature was supportive for other cognitive outcomes, but with low or very low-quality evidence. The evidence so far suggests that noise exposure is associated with cognition, but more good quality research using standardised methodology is required to corroborate these results and to allow for precise risk estimation by larger meta-analyses. There is also a need for more research with older teenagers and young-to-middle aged adults, on the synergistic effects of noise and air pollution, and in Africa, Central and South America, South Asia and Australasia.

Background: Despite a recent increase in engagement with environmental issues among young people, their impact upon adolescent mental health and wellbeing is not yet fully understood. Therefore, this study aimed to explore adolescents' thoughts and feelings about current environmental issues. Methods: Semi‐structured interviews were conducted with a convenience sample of 15 UK‐based adolescents aged 14–18 years (66.7% female). Transcripts were inductively thematically analysed by the interviewing researcher and two adolescent co‐researchers, with priority given to the co‐researchers' impressions to strengthen interpretations of the personal experiences of the interviewees. Results: Six themes were identified: the local environment, efficacy, challenging emotions, information, hindrances and perceptions of the future. The local environment was found to affect adolescents positively and negatively. Factors including greenspace and fresh air had a positive impact, and factors including noise and litter had a negative impact. Most participants reported feeling disempowered to personally influence environmental problems but were engaged with them and felt that trying to make a difference was beneficial for their wellbeing. Adolescents largely reported negative expectations about the environment’s future. Conclusion: The UK adolescents interviewed appeared to be very engaged and emotionally affected by a perceived lack of care towards the environment, locally and globally. It is therefore imperative to amplify young people’s voices and involve them in influencing environmental policy, for the benefit of young people and the planet. Further research should quantify the extent to which environmental issues affect young people's mental health and identify factors that could prevent or alleviate distress.

Although there is increasing evidence that environmental exposures are associated with the risk of neurodegenerative conditions, there is still limited mechanistic evidence evaluating potential mediators in human populations. UK Biobank is a large long-term study of 500,000 adults enrolled from 2006 to 2010 age 40-69 years. ICD-10 classified reports of dementia cases up to 2022 (Alzheimer's disease, vascular dementia, dementia in other classified diseases, and unspecified dementia) were identified from health record linkage. Estimates of residential air pollution, traffic noise, and greenspace exposure have been modelled. Structural brain MRI was conducted from 2014 to 2022, with brain volumes relevant to dementia identified a priori. Associations between environmental exposures, brain volumes, and dementia cases (diagnosed post-MRI) were tested using linear and logistic regression and adjusted for age, sex, household income, ethnicity, education, smoking, and area-level deprivation. Mediation of exposure-outcome associations by plausible brain volumes (those associated with both environmental exposure and dementia outcomes) were modelled using the quasi-Bayesian Monte Carlo method (N = 34,817-39,772). Small but significant mediating effects (2%-8% of relationships mediated) were observed between PM_2.5abs exposure and dementia risk by reduced total brain volume, NOx and Alzheimer's disease risk by reduced peripheral cortical grey matter, PM_2.5abs and vascular dementia risk by reduced peripheral cortical grey matter, PM_2.5abs and other dementia risk by reduced total grey matter, and PM₁₀ and other dementia risk by reduced total grey matter. Greenspace and noise were not associated with dementia outcomes in the subset of the cohort providing brain imaging data. This study adds to existing evidence of associations between environmental exposures and dementia outcomes. Our findings provide novel evidence that differences in brain volume may mediate these relationships. Future research is required to prove this mechanism and establish the other mechanisms through which exposure to air pollution might increase dementia risk.

Background: Adolescents are susceptible to mental illness and have experienced substantial disruption owing to the COVID-19 pandemic. The digital environment is increasingly important in the context of a pandemic when in-person social connection is restricted. Objective: This study aims to estimate whether depression and anxiety had worsened compared with the prepandemic period and examine potential associations with sociodemographic characteristics and behavioral factors, particularly digital behaviors. Methods: We analyzed cross-sectional and longitudinal data from a large, representative Greater London adolescent cohort study: the Study of Cognition, Adolescents and Mobile Phones (SCAMP). Participants completed surveys at T1 between November 2016 and July 2018 (N=4978; aged 13 to 15 years) and at T2 between July 2020 and June 2021 (N=1328; aged 16 to 18 years). Depression and anxiety were measured using the Patient Health Questionnaire and Generalized Anxiety Disorder scale, respectively. Information on the duration of total mobile phone use, social network site use, and video gaming was also collected using questionnaires. Multivariable logistic regression was used to assess the cross-sectional and longitudinal associations of sociodemographic characteristics, digital technology use, and sleep duration with clinically significant depression and anxiety. Results: The proportion of adolescents who had clinical depression and anxiety significantly increased at T2 (depression: 140/421, 33.3%; anxiety: 125/425, 29.4%) compared with the proportion of adolescents at T1 (depression: 57/421, 13.5%; anxiety: 58/425, 13.6%; P for 2-proportion z test <.001 for both depression and anxiety). Depression and anxiety levels were similar between the summer holiday, school opening, and school closures. Female participants had higher odds of new incident depression (odds ratio [OR] 2.5, 95% CI 1.5-4.18) and anxiety (OR 2.11, 95% CI 1.23-3.61) at T2. A high level of total mobile phone use at T1 was associated with developing depression at T2 (OR 1.89, 95% CI 1.02-3.49). Social network site use was associated with depression and anxiety cross-sectionally at T1 and T2 but did not appear to be associated with developing depression or anxiety longitudinally. Insufficient sleep at T1 was associated with developing depression at T2 (OR 2.26, 95% CI 1.31-3.91). Conclusions: The mental health of this large sample of adolescents from London deteriorated during the pandemic without noticeable variations relating to public health measures. The deterioration was exacerbated in girls, those with preexisting high total mobile phone use, and those with preexisting disrupted sleep. Our findings suggest the necessity for allocating resources to address these modifiable factors and target high-risk groups.