Five Years of Long COVID Syndrome: An Updated Review on Cardiometabolic and Psychiatric Aspects

Five years after the outbreak of the coronavirus disease 2019 (COVID-19) pandemic, there is still a significant number of people who have survived COVID-19 but never fully recovered from the disease. They go through an odyssey of doctor visits and a multitude of diagnostic tests, which ultimately do not provide concrete correlations and answers to the question of how exactly long COVID (LC) affects both physical and mental health, and performance. Often, not even highly technical and highly specialized methods, such as cardiac magnetic resonance imaging (MRI), can provide further explanation. Various research efforts continue to investigate the causes, effects and possible treatments of LC, particularly its impact on cognition and mental health. Patients with LC may experience persistent symptoms, but new symptoms also occur. Based on available studies, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) does not only affect the pulmonary system, but nearly every major system and organ, from the brain and heart to the kidneys and immune system. What mechanisms could explain the persistent symptoms of LC and the inadequate recovery? How valuable is an early internal and neurological examination, particularly in the context of psychotherapy? In this review, we examined which factors could contribute to the persistence of LC symptoms and to what extent mitochondrial impairment by LC can explain the symptoms of LC.