Mental illness is one of the most common reasons for years lived with disability and years of life lost. Years of life lost are mainly associated with physical diseases such as cardiovascular diseases, type 2 diabetes, cancer, and chronic obstructive pulmonary disease.
Effects of preventive lifestyle interventions for persons with mental illness are documented in several systematic reviews. The results from the reviews show:
- the documentation lacks direct comparison of the intervention with advice only about healthy lifestyle habits, but such advice may be part of usual treatment.
- the documentation lacks results about effects of interventions on mortality and morbidity.
It is possible, based on low quality evidence, that preventive lifestyle interventions, compared to usual/other/no intervention give
- better quality of life
- improvement of symptoms of mental illness
It is uncertain, based on very low quality documentation, whether the intervention affects medication adherence and psychotic symptoms, compared to usual/other/no intervention.
Mental illnesses such as major depression, anxiety, schizophrenia, and bipolar disorder are among the most common reasons for years lived with disability and years of life lost in Norway. Years of life lost are mainly associated with physical disorders such as cardiovascular diseases, type 2 diabetes, cancer, and chronic obstructive pulmonary disease. Persons with mental illness are less physically active, eat less dietary fibre and fruit and more saturated fat, and smoke more than persons without mental illness. Interventions to promote healthy lifestyle habits may reduce the risk for physical health problems generally, but we don’t know if such interventions can be beneficial for persons with mental illness.
The aim of this overview of systematic reviews was to answer the question “What is the effect of preventive lifestyles interventions such as smoking cessation, increased physical activity, a healthier diet, and reduced alcohol consumption on the physical and mental health and quality of life in persons with mental illness, compared to preventive advice only about lifestyle habits?”
We searched systematically for literature in eight electronic databases. Two persons independently screened publications, selected systematic reviews in full text, and assessed the quality of the included reviews. One author extracted data from the reviews and a second author verified the data extraction. We summarised results relevant to our question in each review. We assessed our confidence in the effect estimates with GRADE (Grading of Recommendations Assessment, Development and Evaluation) and presented the results in text and tables. In the GRADE system, high quality means that we are very confident that the true effect is close to that of the estimate of the effect. Moderate quality means that the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low quality means that the true effect may be substantially different from the estimate of the effect. Very low quality means that the true effect is likely to be substantially different from the estimate of effect.
We found nine systematic reviews of high methodical quality. The reviews included 153 primary studies, the majority being randomised controlled trials. We categorised the populations, according to the authors’ descriptions, as follows: persons with serious mental illness or mental illness, persons with mental illness and type 2 diabetes, or risk of, type 2 diabetes, persons with depression, and persons with schizophrenia or schizoaffective disorder. None of the reviews aimed to directly compare the interventions with advice only about lifestyle habits.
Persons with serious mental illness
Four systematic reviews included persons with serious mental illness. Three of the reviews aimed to evaluate interventions to improve physical activity and dietary habits, and one review targeted physical activity only. One review reported results on quality of life. The standardised mean difference was 0.64 with a 95% confidence interval of 0.35 to 0.92, corresponding to a moderate effect. Two reviews reported results on symptoms of depression, based on different questionnaires with different scales, respectively 0.84 with a 95% confidence interval of 0.49 to 1.18 (large effect), and -0.95 with a 95% confidence interval of -1.90 to -0.0 (large effect). Both results represent improvement of symptoms. One of the reviews reported results on schizophrenia. The standardised mean difference was 1.00 with a 95% confidence interval of 0.37 to 1.64 (large effect, improvement of symptoms). We assessed our confidence in the effect estimate for these outcomes as low. One review evaluated effects of interventions on quality of life and medication adherence but did not report the actual results, and we assessed our confidence in the effect estimate for these outcomes as very low. One review aimed to evaluate effects of intervention on incidence of cardiovascular disease, but none of the included primary studies reported on this outcome.
Persons with mental illness and type 2 diabetes, or risk of type 2 diabetes
Two systematic reviews included persons with mental illness and type 2 diabetes, or risk of, type 2 diabetes. One of the reviews evaluated interventions to improve dietary habits and/or physical activity and reported numbers on symptoms of depression. The standardised mean difference was -0.16 with a 95% confidence interval of -0.27 to -0.06 (small effect, reduction of symptoms). We assessed our confidence in the effect estimate as low. The other review aimed to evaluate effects of interventions to improve self-management on mortality, but did not find primary studies that reported on this outcome.
Persons with mental illness
One systematic review included persons with mental illness and evaluated effects of internet-based interventions on physical activity. The authors reported results from two primary studies where the effect size was 0.07 (small or no effect) and 0.67 (moderate effect, improvement of symptoms), respectively. Confidence intervals were not reported. We assessed our confidence in the effect estimate as low.
Persons with depression
One systematic review included persons with depressive disorders and evaluated effects of interventions for change of lifestyle habits. The authors reported on symptoms of depression, but did not report actual results for all included primary studies. The effect is uncertain.
Persons with schizophrenia of schizoaffective disorders
One systematic review included with schizophrenia or schizoaffective disorders and evaluated effects of interventions to change lifestyle habits such as smoking, diet and physical activity. The authors reported on psychotic symptoms but did not report results. The effect is uncertain.
The included systematic reviews covered several populations of persons with mental illness. Because a uniformly accepted definition of the concept “serious mental illness” is lacking, we chose to use the concepts used by the authors in the included reviews. The interventions targeted one or more lifestyle habits, most often physical activity and diet and were given individually or in groups. The content was based on counseling and support for change, and participation in exercise if the interventions targeted physical activity. Reports of comparisons were often lacking, or generally described as usual, no, or other intervention. Although none of the reviews explicitly aimed to compare interventions with advice about lifestyle habits only, we chose to include reviews with any comparison. This is a deviation from the protocol. We argue, however, that it is helpful to report available evaluations of the interventions. Of the primary outcomes mortality, morbidity, quality of life, and medication adherence, quality of life was the only one documented. Most of the available documentation concerned the secondary outcome mental health.
Overviews of systematic reviews summarize knowledge on broad questions, e.g. effects of an intervention or similar interventions in several populations. The approach is systematic, standardised, and transparent. Downsides may be that information is lost in summarizing primary studies, and that recently published studies have not yet been included in systematic reviews, leading to incomplete documentation.
We didn’t find documentation about effects of the interventions on mortality and morbidity. Randomised controlled trials with large numbers of participants and long follow-up periods are necessary to document effects in these outcomes. Multicentre studies involving large research groups will probably be suited to recruit enough participants and minimize risk of bias.
Preventive interventions for improving lifestyle habits in persons with mental illness may improve quality of life and symptoms of depression compared to usual, other, or no intervention. It is uncertain whether the interventions change medication adherence or psychotic symptoms compared to usual, other, or no intervention. We don’t know if the interventions affect morbidity and mortality. The documentation lacks direct comparison of the interventions with preventive advice on lifestyle habits only.