Common mental disorders (CMD), such as anxiety and depression, are a leading cause of the global disease burden, and their prevalence increased during the pandemic in some populations. Mental disorders are more common in people with physical illnesses, and their treatment is complicated by adverse effects, pharmacological interactions, and contraindications of antidepressant drugs. Mental disorders are also associated with risk factors for medical illnesses, such as poor cardiovascular health and sarcopenia. Frailty, a major geriatric syndrome, is characterized by increased vulnerability to stressors. Minor insults can result in disproportionate health changes. It develops from the accumulation of molecular and cellular damage throughout life and is associated with adverse outcomes in older adults. Two main frailty models exist: the physical phenotype (at least three of: unintentional weight loss, exhaustion, low energy expenditure, slowness, and weakness) and the Frailty Index (accumulation of age-related health deficits). The relationship between frailty and psychiatric comorbidities, such as depression, has been extensively studied. Frail individuals have higher odds of prevalent and incident depression, and depressed individuals have higher odds of prevalent and incident frailty. Despite shared symptomatology and sociodemographic predictors, studies show frailty and depression are distinct but highly correlated constructs. However, the relationship between frailty and other mental disorders beyond depression is less explored. Cross-sectional studies have shown associations of anxiety symptoms with pre-frail status and frailty in older adults. The stressful COVID-19 pandemic environment may put frail individuals at higher risk of CMD, potentially worsening outcomes. This study aimed to investigate the association of frailty status before the pandemic with prevalent and incident CMD in older adults in São Paulo, Brazil, during the pandemic's peak.

The literature review extensively covers the prevalence and impact of common mental disorders (CMDs) like anxiety and depression, particularly their exacerbation during the COVID-19 pandemic. It highlights the established link between CMDs and physical illnesses, emphasizing the complexities in treating mental health conditions in individuals with comorbidities. The review delves into the existing research on frailty, its various definitions (physical phenotype and Frailty Index), and its established association with adverse health outcomes in older adults. A significant portion is dedicated to the well-documented correlation between frailty and depression, including longitudinal studies showing the increased likelihood of new depressive symptoms in frail individuals. However, the review also points out the limited research on the connection between frailty and other CMDs beyond depression, noting some existing cross-sectional studies that explored the relationship between frailty and anxiety symptoms. Finally, the introduction contextualizes the study's focus on the potential increased vulnerability of frail older adults to CMDs during the pandemic due to the increased stress and societal disruption.

This study used data from the ELSA-Brasil study, a prospective longitudinal cohort of Brazilian civil servants. The study included 706 participants aged 60 and older who completed both the on-site wave (2017-2019) and the first online COVID-19 assessment wave (May-July 2020). Common mental disorders (CMDs) were assessed using the Brazilian version of the Clinical Interview Schedule-Revised (CIS-R), a structured interview administered in person in 2017-2019 and via a validated electronic self-report version in 2020. A CIS-R score ≥12 defined CMD. Persistent CMD was defined as a score ≥12 in both assessments, while incident CMD was defined as a score <12 in 2017-2019 and ≥12 in 2020. Frailty was assessed using two definitions: the Frailty Index (FI), calculated from 36 health deficits measured across study waves, with FI ≥ 0.25 indicating frailty; and the physical frailty phenotype, defined as the presence of at least three of five criteria (unintentional weight loss, self-reported exhaustion, low energy expenditure, slow gait speed, and weak grip strength). Sociodemographic characteristics (age, sex, education, race) were also collected. Statistical analysis involved descriptive statistics, comparisons of characteristics across frailty groups using appropriate tests (t-tests, Wilcoxon rank-sum test, chi-square test, Fisher's exact test, ANOVA, Kruskal-Wallis test), and logistic regression models to investigate the association between frailty (both FI and phenotype) and persistent/incident CMD, adjusted for sociodemographic factors. Sensitivity analyses excluded exhaustion from frailty definitions to address potential overlap with psychiatric symptoms. Effect modification by age, sex, and education was also tested.

The study included 706 participants (mean age 69.2 ± 5.4 years; 54.7% female). 42 participants (6.0%) had persistent CMD, and 48 (6.8%) had incident CMD. 75 participants (10.6%) were frail according to the Frailty Index, and 31 (4.4%) were frail according to the physical phenotype. Adjusted logistic regression analysis revealed significant associations between frailty (both definitions) and persistent CMD. Frail participants had significantly higher odds of persistent CMD compared to robust individuals (Frailty Index: OR = 8.61, 95% CI = 4.08-18.18; physical phenotype: OR = 23.67, 95% CI = 7.08-79.15). Pre-frail individuals according to the physical phenotype also had significantly higher odds of persistent CMD (OR = 3.54, 95% CI = 1.50-8.38). Frailty was also associated with incident CMD, regardless of the definition used (Frailty Index: OR = 2.79, 95% CI = 1.15-6.78; physical phenotype: OR = 4.37, 95% CI = 1.31-14.58). However, pre-frailty was not significantly associated with incident CMD. Analysis of the Frailty Index as a continuous variable showed that each 0.01 increment was associated with a 12% higher odds of persistent CMD (OR = 1.12, 95% CI = 1.08-1.17) and a 4% higher odds of incident CMD (OR = 1.04, 95% CI = 1.00-1.08). Sensitivity analyses excluding exhaustion from the frailty definitions did not change the association between frailty and persistent CMD but rendered the associations between frailty and incident CMD insignificant. Age, sex, and education were not effect modifiers.

This study demonstrated a strong association between pre-pandemic frailty and both persistent and incident common mental disorders (CMDs) during the first wave of the COVID-19 pandemic in older adults. This association held true for both commonly used frailty definitions (Frailty Index and physical phenotype), strengthening the findings' robustness. The results align with pre-pandemic studies linking frailty to depression and, to a lesser extent, anxiety. The study's strength lies in using a validated assessment tool (CIS-R) for CMDs consistently across both pre-pandemic and pandemic assessments, employing multiple frailty definitions, and showing robust results even after excluding exhaustion, a symptom overlapping with psychiatric conditions. The findings highlight the vulnerability of frail older adults to the mental health impacts of the pandemic and underscore the need for proactive identification and support strategies for this population, which experienced more severe consequences from social restrictions compared to robust individuals. While findings align with several previous studies, contrasting results exist. This could be attributed to factors like different psychiatric assessment scales used in other studies. The results also highlight a substantial mental health toll on older adults during the initial phase of strict social distancing measures. The study's strength lies in its rigorous methodology and robust findings that demonstrate a clear association between frailty and increased odds of mental health challenges during a pandemic.

This study demonstrates a strong association between pre-existing frailty and increased odds of both persistent and incident common mental disorders (CMDs) in older adults during the initial wave of the COVID-19 pandemic. This highlights the vulnerability of this population to the mental health consequences of the pandemic. The findings emphasize the importance of identifying frail older adults as a high-risk group and implementing targeted interventions to mitigate mental health burdens and support their well-being during and after pandemics.

The study's limitations include a relatively long interval (1-3 years) between psychiatric assessments, which might have missed some fluctuations in CMD symptoms. The use of an online self-report version of the CIS-R during the pandemic, although validated, might differ from the in-person administration, potentially introducing bias. The sample size limited the investigation of specific psychiatric diagnoses. While 36 health deficits were included in the FI, some variables relied on older data (2008-2010), which may have led to some misclassification. The lack of data on social isolation and SARS-CoV-2 infection timing in relation to CMD assessment is another limitation. Finally, a substantial portion of the São Paulo sample did not participate in the online COVID-19 assessment.