RESUMEN
The COVID-19 pandemic caused immediate and far-reaching disruption to society, the economy, and health-care services. We synthesised evidence on the effect of the pandemic on mental health and mental health care in high-income European countries. We included 177 longitudinal and repeated cross-sectional studies comparing prevalence or incidence of mental health problems, mental health symptom severity in people with pre-existing mental health conditions, or mental health service use before versus during the pandemic, or between different timepoints of the pandemic. We found that epidemiological studies reported higher prevalence of some mental health problems during the pandemic compared with before it, but that in most cases this increase reduced over time. Conversely, studies of health records showed reduced incidence of new diagnoses at the start of the pandemic, which further declined during 2020. Mental health service use also declined at the onset of the pandemic but increased later in 2020 and through 2021, although rates of use did not return to pre-pandemic levels for some services. We found mixed patterns of effects of the pandemic on mental health and social outcome for adults already living with mental health conditions.