This review focuses on assessing the prevalence and risk factors of mental disorders in older adults in the current era, including the COVID-19 pandemic. A systematic review of the literature in PubMed, Elsevier, Google, using keywords over the past 10 years was conducted. It is shown that data on the prevalence of psychiatric disorders in the elderly population, including in comparison with young adults, diverge significantly. The significant incidence of mental disorders among nursing home residents is highlighted. The relevance of non-psychotic disorders of the depressive and anxiety spectrum in older adults is demonstrated. The difficulty of diagnosing mental disorders associated with somatic pathology as well as cognitive disorders in elderly patients is demonstrated. Risk factors for mental disorders in older adults are socio-demographic as well as economic, psychological and somatic factors. The problem of mental health of the elderly under the COVID-19 pandemic associated with specific risk factors for mental disorders is characterized. The shortage of evidence-based research in the treatment of mental disorders in old age and the urgency to improve the organization of psychiatric care for such patients are noted. Understanding the structure and prevalence of mental disorders among the elderly will allow to optimize the work of the healthcare system.