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Memory issues, mental fatigue, difficulty concentrating: long Covid often leaves lasting marks on the brain. Between cognitive rehabilitation, brain stimulation and emerging biological insights, science is now untangling promising leads, limitations and what we know for sure.

Since the emergence of Covid-19, a growing number of patients have reported symptoms that persist long after the acute infection has passed. Neurological after-effects are among the most worrying: memory loss, difficulty finding words, brain fog, persistent fatigue. According to data published by Santé Publique France, nearly 30% of people affected by long Covid report at least one cognitive or neurological symptom several months after the initial infection.

But where do these symptoms come from? Research is progressing rapidly, and studies increasingly agree on one point: these symptoms are neither imaginary nor merely psychological. Several recent findings, including those from the Institut Pasteur, show that the virus can alter neuronal activity, particularly in the brainstem. In some cases, traces of the virus or its effects linger in the nervous system, which may explain why symptoms persist. Other studies, published in the scientific journal Brain, show that some patients exhibit markers of brain inflammation or disruptions in neuronal metabolism similar to what is observed in certain neurodegenerative diseases.

These discoveries underscore the need for targeted treatments and appropriate care. Since 2023, new approaches have been tested in France, Europe and the United States to repair or improve cognitive function after long Covid. Among them, intensive cognitive training has generated significant interest. Inspired by post-stroke motor rehabilitation, this method involves regular, personalized exercises designed to stimulate memory, attention and executive functioning. A pilot study published in 2025 in the Journal of Neurorehabilitation showed that some patients experienced significant improvement in concentration and mental processing speed after six weeks of tailored training.

Targeted Stimulations

Other teams are going further by exploring non-invasive brain stimulation. This involves using mild electrical impulses or low-intensity ultrasound to activate specific regions of the brain. One study on patients suffering from brain fog identified a particular deficit in the right insula, a region involved in perception and self-awareness. By applying targeted stimulation to this area, researchers observed improvements in perceptual and cognitive abilities in some patients. These findings, published on the arXiv platform in 2025, open new possibilities: in the future, it may be possible to offer treatments tailored to each patient’s specific brain profile.

More experimental approaches are also being tested, including stimulation using vibration or gamma-range sound waves. A pilot trial published in Frontiers in Cognition reported improvements in fatigue and memory, though the sample size remains very small. Meanwhile, traditional rehabilitation, combining psychological support, stress management, physical activity and gradual re-engagement in intellectual tasks, remains an essential foundation.

Nonetheless, caution is still needed. A major American trial, the RECOVER-NEURO program, compared three different approaches in more than 300 patients: online cognitive training, structured rehabilitation, and non-invasive brain stimulation. After ten weeks, none of these methods showed clear benefits compared to standard supportive care. Researchers emphasize that many studies remain small, short-term, or lack control groups. Long Covid also manifests very differently from one patient to another, making a universal treatment difficult to identify.

Despite these limitations, research is moving forward. The approaches tested today will help pinpoint the exact causes of cognitive symptoms and refine future treatments. Already, the concept of comprehensive brain rehabilitation combining exercises, targeted stimulation, psychological support and long-term follow-up, is emerging as a priority in long Covid care. For many specialists, the key lies in a multidisciplinary approach that brings together neurology, psychology, physical medicine and the active involvement of patients.

Nothing is guaranteed yet, but each step forward brings patients a little closer to reclaiming a normal life. For many, the goal is less about “repairing” the brain than about giving it new strategies to compensate for, work around or ease the damage left by the virus.