Abstract: This review focuses on assessing the prevalence and risk factors of mental disorders in older people in the modern era, including the COVID-19 pandemic. A systematic review of the literature was conducted in PubMed, Elsevier, and Google using keywords over the past 10 years. Substantial discrepancy of data on the prevalence of psychiatric disorders has been shown in the elderly population. The significant incidence of mental disorders among nursing home residents is highlighted. The relevance of nonpsychotic depressive and anxiety disorders is demonstrated for the elderly, along with the difficulty of diagnosing mental disorders associated with physical pathology and cognitive impairments. The risk factors for mental disorders in older adults are socio-demographic but also economic, psychological, and physical. The problem of mental health of the elderly is characterized for the conditions of the COVID-19 pandemic associated with specific risk factors for psychiatric disorders. The shortage of evidence-based research in the treatment of mental disorders in the elderly 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 optimizing the functioning of healthcare systems.