On the psychiatric level in particular, the study by Taquet et al. (2021) on a cohort of 236,279 patients diagnosed positive for COVID-19 and compared to two control cohorts of patients with respiratory impairment is in the direction of an increased risk of psychotic disorders in the COVID-19 cohort at 6 months. The authors suggest that these psychiatric sequelae and neurological impairments would last well beyond 6 months (Taquet et al., 2021), and would not be limited to patients who have been hospitalized. Several mechanisms could explain these observations, especially at the neurological level. In this sense, a recent study (Song et al., 2020) shows direct neuronal infection with COVID-19.

Cognitively, post-COVID-19 complications are still poorly understood. In the post-acute phase, between 2 and 3 weeks after COVID-19 infection, Zhou et al. (2020) highlight a sustained attention impairment via the evaluation of 29 patients aged 30 to 64 years, matched to a control group. The TMT, the Codes, the empans and the CPT-II are offered digitally to both groups. In this study, only CPT-II appears sensitive enough to show a significant difference between these groups. In particular, the authors highlight a reduction in the number of correct answers and an increase in the number of errors in the 2^th and 3^th parts of the test, but a shorter response time in the 1^st and 2^th parts of the CPT-II for patients. The increase in TR is also directly related to the degree of the inflammatory response (measured using the concentration of C-reactive protein in the blood) (Zhou et al., 2020). This general inflammatory reaction has also been described in other conditions such as poliomyelitis, influenza, in certain infections (CMV, EBV, neuro-HIV,...) and implicated in the spectrum of chronic fatigue syndrome, etc.

More broadly, executive and attentional difficulties are found in 36% of patients (Helms et al., 2020; Ardila & Lahira, 2020), including after recovery from COVID-19 (Almeria et al., 2020; Song et al., 2020; Woo et al., 2020), in addition to memory alterations. Indeed, the hippocampus, a subcortical structure crucial in memory functioning, also appears to be vulnerable to COVID-19 (Ritchie et al., 2020). Guedj et al., (2021) talk about hypo-metabolism affecting the olfactory bulb, limbic regions, brain stem and cerebellum.

 In the longer term, a recent meta-analysis correlates current clinical manifestations with possible future neurological consequences (Mahalakshmi et al. 2020), thus alerting the medical profession to the potential consequences of COVID-19. Miners et al. (2020) recall in particular this link between the neurological conditions observed in COVID-19, and particularly ischemic and hemorrhagic strokes, and the cognitive consequences that this can entail, particularly because of the vulnerability of white matter networks. Networks of white substances appear to play a crucial role in cognitive functioning, and in particular in the question of the speed of information processing (Miners et al., 2020). Frontal regions in particular would combine a double vulnerability in the case of COVID-19 (Miners et al., 2020) and explain the resurgence of frontal subcortical profiles in this pathology.

The impact of neuro-viral disorders on the speed of treatment via frontal corticosteroid disorder was already known before (Stankoff et al., 2001). Indeed, the slowing of the speed of information processing is one of the characteristic symptoms of subcortical-frontal profiles that are most frequently associated with neuro-viral disorders such as COVID-19 or neuro-HIV. Whether it is related to the cerebral tropism of the virus, the local inflammatory response it elicits or a mixture of both, ideo-motor slowdown is a very common and early symptom during these subcortical-frontal disorders. Through its impact on information processing, it plays a pre-eminent role in the difficulties faced by patients in their daily lives. It is linked to neuropathological involvement and is therefore an excellent marker of subcortical deficits (Suarez et al., 2001). It is also one of the most sensitive symptoms to therapeutic adjustments.

The cognitive effects of COVID must also be understood under the side of more general psychiatric and emotional functioning (depression, anxiety, sleep disorders, post-traumatic stress disorder, etc.).

The consequences of the health crisis can be observed even in people who have not been directly affected by COVID-19. In this sense, Kocevska et al. (2020) warn about the effects of the health crisis on sleep quality by highlighting a cross-effect between pre-COVID and post-COVID-19 sleep quality, the direction of sleep evolution being a function of the quality evaluated of it upstream (Figure 2). Negative affects and worry in particular are the best predictors of deterioration in sleep quality (Kocevska et al., 2020; Kossigan Kokou-Kpolou et al., 2020). Taking sleep into account in assessing the consequences of COVID-19 also appears crucial because of the link between sleep, psychiatric conditions, and the increased risk of new pathologies (Kossigan Kokou-Kpolou et al., 2020). Moreno et al., (2020) complete this idea by recalling that the health crisis related to COVID-19 is causing an increase in anxio-depressive symptoms, particularly through the increase in psychosocial stress.