A systematic review and meta-analysis published in JAMA Network Open is examining how mental health symptoms changed from the period before the COVID-19 pandemic to the months and years during it, with a central focus on differences associated with sex and gender. The study addresses a question that became increasingly important as the pandemic disrupted health care, education, employment, family life and social networks worldwide: did psychological distress rise in the same way for everyone, or were some groups affected more severely than others?
The research brings together evidence from multiple studies rather than relying on a single population or location. In a systematic review, investigators use predefined methods to identify, evaluate and synthesize relevant scientific literature. A meta-analysis then applies statistical techniques to combine compatible results, producing an overall estimate of change while also examining how much findings vary between studies. This approach can reveal broad patterns that may be difficult to detect in individual investigations, although the strength of its conclusions depends on the quality, consistency and comparability of the underlying research.
The study’s primary comparison is between mental health symptoms measured before the emergence of COVID-19 and symptoms assessed during the pandemic. Such symptoms can include indicators of depression, anxiety and other forms of psychological distress, although the specific measures and outcomes are detailed in the full article. Comparing pre-pandemic and pandemic data is technically challenging because studies may use different questionnaires, thresholds, sampling strategies and follow-up periods. Researchers must therefore account for methodological differences when estimating whether observed changes represent a consistent population-level pattern.
Sex and gender are treated as important analytic dimensions in the review. Sex generally refers to biological characteristics, while gender encompasses social roles, identities, relationships and structural experiences. These concepts are not interchangeable, and the way they are defined or recorded can influence the interpretation of mental health data. A study that separates participants only into binary sex categories may capture a different set of effects than research that examines gender identity, gender expression or the social conditions associated with gender.
The pandemic created several pathways through which mental health could be affected. Fear of infection, bereavement, isolation, financial insecurity and interruption of routine care all generated psychological pressure. Lockdowns and school closures altered the distribution of paid and unpaid work, while health care workers and caregivers faced additional responsibilities and occupational risks. At the same time, access to mental health services changed rapidly, with many consultations moving online. These factors did not affect all populations equally, making subgroup analysis essential for understanding the pandemic’s consequences.
A meta-analysis focused on sex and gender can also help identify whether apparent differences are robust across countries and study designs or whether they depend on particular settings. Statistical heterogeneity—the degree to which study results differ beyond what would be expected from sampling variation—is especially important in pandemic research. High heterogeneity may indicate that effects varied according to age, geography, socioeconomic conditions, timing, exposure to infection or the policies in place. Investigators may use subgroup analyses, sensitivity tests and statistical models to explore these sources of variation.
The review is led by corresponding author Brett D. Thombs, PhD, of the Lady Davis Institute for Medical Research at Jewish General Hospital in Montreal, Canada. It appears in JAMA Network Open and is associated with the DOI 10.1001/jamanetworkopen.2026.27595. The journal’s description identifies the work as a systematic review and meta-analysis of changes in mental health symptoms before and during COVID-19, analyzed by sex and gender. The material supplied for this report does not include the study’s numerical results, the number of studies and participants analyzed, or the authors’ final estimates of symptom change.
Those details will determine how the findings should be interpreted by clinicians, public health authorities and researchers. If the analysis identifies consistent differences between groups, the evidence could support more precisely targeted mental health monitoring and services during future infectious-disease emergencies. If results vary substantially, that variation may be equally important, signaling that broad labels such as “women,” “men” or “gender-diverse people” can conceal differences created by age, income, race, occupation, family responsibilities, disability or access to care. The study therefore contributes to a larger scientific effort to understand mental health as an outcome shaped by both biological and social conditions.
The publication also underscores the importance of collecting better data during health crises. Future studies can improve comparisons by using repeated measurements from the same participants, clearly distinguishing sex from gender, reporting gender-diverse populations separately when sample sizes permit, and applying consistent symptom instruments. Linking mental health assessments with information about infection, vaccination, restrictions, employment and health care access may further clarify causal pathways. As the scientific community continues to evaluate the pandemic’s long-term effects, analyses that examine not only whether symptoms changed but also for whom, when and under what conditions will be critical to designing equitable responses.
Subject of Research: Changes in mental health symptoms before and during the COVID-19 pandemic, analyzed by sex and gender.
Web References: https://doi.org/10.1001/jamanetworkopen.2026.27595
Keywords: Mental health, COVID-19, sex differences, gender, systematic review, meta-analysis, psychological symptoms, pandemic health, mental health disparities, viral science news
