Mental disorders affect almost 30% of individuals across the lifespan . There are already a lot of psychotherapies and pharmacological treatments available for these individuals. However, there remains a large proportion of people who do not benefit fully form standard treatment [2,3]. Therefore, new approaches towards the prevention and treatment of mental health problems are needed. These can be delivered alongside traditional mental health care. But what could these new approaches include?
Lifestyle factors might be an outcome: an emerging body of research has linked both the onset and symptoms of various mental disorders to lifestyle factors. This term refers to health behaviors such as physical exercise, diet, tobacco smoking and sleep . One large study examined the effects of such lifestyle factors, by summarizing all studies that have been done in this field . In this way, they could examine causal relations between key modifiable health behaviors (physical activity, dietary food intake, tobacco smoking, and sleep) and the incidence and outcomes of major mental disorders, including depression, anxiety and stress-related disorders, attention-deficit/hyperactivity disorder (ADHD), bipolar disorder, schizophrenia and related psychotic disorders.
So what did they find? First, they found that exercise interventions may provide effective adjunctive treatment for depression, anxiety and stress-related disorders, psychotic disorders, and ADHD. For the treatment of diagnosed mental illness, supervised exercise interventions are recommended, incorporating moderate-to-vigorous activity, and delivered by trained exercise professionals.
Second, poor sleep has been shown to be a key modifiable lifestyle factor, showing links with various psychiatric disorders and a causal role in bipolar disorder. Sleep problems have also been found to increase the risk of suicidal behavior in people with mental health problems . It also has been found that sleep interventions could reduce symptoms of depression.
Third, there were strong indications for smoking, a causal factor in the onset of major depression, bipolar disorder, and schizophrenia. Smoking was also associated with an increased prospective risk of mental disorders, earlier age of onset, and adverse outcomes in people with mental disorders [7,8]. People with a mental illness who stopped smoking improved on psychological well-being.
Fourth, the causal effects of diet on common and severe mental illnesses were less clear. Several studies have shown that healthy dietary patterns could be associated with a significantly reduced risk of depressive symptoms. There is also preliminary evidence for specific dietary interventions in ADHD (for example an elimination diet). More research in this promising field is needed. The Eat2beNICE consortium includes different studies to gain more knowledge about the relationship between diet and mental health (https://newbrainnutrition.com/for-general-public/clinical-trials/).
But, how can these lifestyle factors have an impact on mental health, how does this work? One potentially shared biological mechanism by which several adverse health behaviors could increase the risk of mental illness is inflammation, which has been linked to a broad range of psychiatric disorders . Previous research has indicated anti-inflammatory effects from exercise, Mediterranean diet, improved sleep, and smoking cessation, so this may partially explain the effects of lifestyle interventions on improving mental health. Another mechanism that could explain the link between lifestyle factors and mental health is the role of the gut microbiome. Since the microbiome appears to be influenced by exercise and diet, this could be considered as another potential pathway through which health behaviors could impact mental health. However, more research on these underlying mechanisms is needed. One of the goals of the Eat2beNICE is to gain more knowledge about these possible underlying mechanisms, such as the gut microbiome.
Finally, if we know more about the underlying mechanisms and what lifestyle factors could benefit people with mental disorders, how could this be applied in clinical settings? Some options include a) using behavior change techniques; b) involving dedicated “physical health” staff, such as professionals in specific aspects of health behavior change; c) training mental health staff in the importance and goals of lifestyle interventions; and d) facilitating peer-support to improve uptake and adherence .
 Kessler RC, Demler O, Frank RG et al. Prevalence and treatment of mental disorders, 1990 to 2003. N Engl J Med 2005;352:2515-23.
 Patel V, Saxena S, Lund C et al. The Lancet Commission on global mental health and sustainable development. Lancet 2018;392:1553-98.
 Correll CU, Rubio JM, Kane JM. What is the risk-benefit ratio of long-term antipsychotic treatment in people with schizophrenia? World Psychiatry 2018;17:49-60.
 Lianov L, Johnson M. Physician competencies for prescribing lifestyle medicine. JAMA 2010;304:202-3.
 Joseph F , Marco S, Wootton RE, et al. A meta‐review of “lifestyle psychiatry”: the role of exercise, smoking, diet and sleep in the prevention and treatment of mental disorders. World Psychiatry 2020;19:360-380.
 Wang X, Cheng S, Xu H. Systematic review and meta-analysis of the relationship between sleep disorders and suicidal behaviour in patients with depression. BMC Psychiatry 2019;19:303.
 Gurillo P, Jauhar S, Murray RM et al. Does tobacco use cause psychosis? Systematic review and meta-analysis. Lancet Psychiatry 2015;2:718-25.
 Sankaranarayanan A, Mancuso S, Wilding H et al. Smoking, suicidality and psychosis: a systematic meta-analysis. PLoS One 2015;10:e0138147.
 Yuan N, Chen Y, Xia Y et al. Inflammation-related biomarkers in major psychiatric disorders: a cross-disorder assessment of reproducibility and specificity in 43 meta-analyses. Transl Psychiatry 2019;9:1-13.