Conclusion : SARS Cov2, a time bomb for neurological and psychiatric disease?
Even though the long term effects of SARS Cov2 infection are highly speculative at the moment, several hints constitute a significant warning for the clinical and scientific community to assess 1. the middle term and late effects of Covid 19 (Serrano-Castro, Estivill-Torrús et al. 2020) and 2. The links between viruses and nervous system function in general.
First, as aforementioned, the acute effects of viral infections demonstrate how devastating viruses may be for the nervous system. Viruses are able to affect motor system, cognitive function, memory, etc, sometimes irreversibly. The effect of viral infections may be direct, but also indirect (cytokine storm (Huang, Wang et al. 2020, Mehta, McAuley et al. 2020), but also low-level inflammation (Bechter 2013)), increasing the complexity of pathophysiological mechanisms. Epidemiological and clinical observations have demonstrated tight links between viral infections and neurological & psychiatric disorders. Viruses are able to establish latent and chronic infections, and undergo recurrent reactivation. While viruses may induce inflammation, many of them may induce little or no such effect, being of overall low pathogenicity for the infected host. This evolutionary advantage for the virus might indeed constitute the basis of complex interactions between the pathogen and the host, leading to potential dormancy of the virus, but accumulating dysfunction over time (Bechter 2013). Indeed, detection of viruses in the central nervous system of patients remains challenging. Which virus to look for ? How much time –sometimes decades- after the infection ? In which brain area ? What biological strategy may the virus have used to escape the immune system ? Do epidemiological associations between viral infection and chronic disease constitute a direct link or indicate a risk factor ?
All these fascinating questions call for interdiscisplinary research, where neuroscience and virology will undoubtedly gain from an increase in interactions to decipher the pathophysiological mechanisms of neurological and psychiatric diseases.
PP