The COVID-19 pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in numerous health complications, including cognitive impairment.
Previous studies have highlighted that a significant proportion of COVID-19 survivors experience persistent cognitive issues, such as impaired memory, attention, concentration, executive function, and information processing speed.
However, with the emergence of the Omicron variant, it remains unclear whether individuals infected with this particular variant also face similar cognitive challenges. This article presents findings from a cross-sectional cohort study conducted to investigate cognitive impairment in patients infected with the Omicron variant.
Study Design and Methods
The study enrolled 215 patients infected with the SARS-CoV-2 Omicron BA.2.2.1 variant at Shanghai Fourth People’s Hospital between April 2022 and August 2022. The cohort included 142 asymptomatic individuals and 73 mild cases without pneumonia. The control group consisted of 215 age- and gender-matched healthy individuals who tested negative for COVID-19.
The study excluded participants with a history of cerebral hemorrhage, traumatic brain injury, neurological or psychiatric diseases, speech impairment, severe visual or hearing impairment, malignant tumor, alcoholism, drug abuse, and psychotropic substance abuse. Cognitive function was assessed using the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA). The data were analyzed using statistical tests, and significance was set at p < 0.05.
The total scores of MMSE and MoCA in patients infected with the Omicron variant were comparable to those of the control subjects. However, when stratified by age, patients aged 50 years or older exhibited significantly lower total scores of MMSE and MoCA compared to controls.
The female patients aged over 50 also showed significantly lower scores, while male patients in the same age group did not display significant cognitive impairment. Specifically, patients over 50 infected with the Omicron variant demonstrated lower scores in attention, calculation, forward/backward digit span, serial 7 s-administration, verbal fluency, and abstraction. These findings suggest that the Omicron variant may be associated with cognitive decline, particularly in older individuals.
Discussion and Implications
This cross-sectional cohort study provides preliminary evidence of cognitive impairment in patients aged over 50 infected with the Omicron BA.2.2.1 variant of SARS-CoV-2. While the small sample size limits the generalizability of the findings, this study highlights the importance of addressing cognitive decline induced by COVID-19 infection, especially in the context of an aging society.
The observed cognitive impairment in patients without severe symptoms suggests that peripheral inflammation, endothelial disruption, microglial activation, neurotransmitter depletion, microvascular compromise, leukoencephalopathy, and cortical atrophy may contribute to network dysfunction and cognitive changes.
It is important to note that the screening tools used in this study, MMSE and MoCA, have limitations in assessing cognitive performance comprehensively. Future studies employing functional MRI and PET-CT should be conducted to explore potential alterations in brain function and structure among patients infected with the Omicron variant.
Furthermore, it is crucial to determine whether the cognitive dysfunction observed is specific to SARS-CoV-2 or simply a manifestation of sickness behavior. Although sickness behavior was observed in both asymptomatic and mild cases, cognitive impairment was only evident in patients aged over 50, suggesting a potential influence of the Omicron variant on cognitive performance and neural circuit functions.
In conclusion, this cross-sectional cohort study provides initial insights into the cognitive impairment associated with the Omicron variant of COVID-19. The findings suggest that patients aged over 50 infected with the Omicron BA.2.2.1 variant display cognitive dysfunction, emphasizing the need for increased attention to the cognitive decline induced by COVID-19 infection, particularly in an aging society.
The study highlights the potential role of peripheral inflammation, endothelial disruption, microglial activation, neurotransmitter depletion, microvascular compromise, leukoencephalopathy, and cortical atrophy in mediating cognitive changes.
While the study employed the MMSE and MoCA as screening tools, future research should incorporate more comprehensive assessments such as functional MRI and PET-CT scans to provide a deeper understanding of potential alterations in brain function and structure in patients infected with the Omicron variant. These advanced imaging techniques can offer valuable insights into the underlying mechanisms of cognitive impairment associated with COVID-19.
Moreover, it is important to differentiate whether the observed cognitive dysfunction is specific to SARS-CoV-2 or merely a manifestation of sickness behavior. Although sickness behavior was present in both asymptomatic and mild cases, the cognitive impairment was predominantly observed in patients aged over 50, suggesting a potential direct effect of the Omicron variant on cognitive performance and neural circuit functions.
Long-term monitoring of cognitive function and neural circuitry in individuals infected with the Omicron variant would provide a more comprehensive understanding of the lasting effects of the virus on cognitive health.
The implications of this study extend beyond individual patients to the broader healthcare system and society. As the population continues to age, understanding the cognitive consequences of COVID-19 becomes increasingly crucial. Healthcare providers should be aware of the potential cognitive impact of the Omicron variant, especially in older patients, and consider incorporating cognitive assessments into post-COVID-19 care. Early detection and intervention for cognitive impairment can help improve patient outcomes and quality of life.
Furthermore, these findings emphasize the importance of public health measures to prevent COVID-19 infection and transmission. The transmissibility and ability of the Omicron variant to spread in populations with high levels of immunity highlight the need for ongoing vigilance and adherence to preventive measures such as vaccination, mask-wearing, and physical distancing. By reducing the overall burden of COVID-19 cases, we may also mitigate the potential long-term cognitive consequences of the disease.
In conclusion, this cross-sectional cohort study provides initial evidence that patients aged over 50 infected with the Omicron BA.2.2.1 variant of SARS-CoV-2 may experience cognitive impairment. While further research is needed to confirm and expand upon these findings, they underscore the importance of prioritizing cognitive health in the context of COVID-19, particularly in older individuals. By recognizing and addressing cognitive impairment as a potential consequence of the disease, we can improve the overall well-being and outcomes of individuals affected by COVID-19.
reference link :https://translationalneurodegeneration.biomedcentral.com/articles/10.1186/s40035-023-00357-x