A study conducted by Joan Machamer et al. found that over two-thirds of concussion patients report persistent symptoms a year post-injury. At the 12 month evaluation, 50 percent of participants reported at least three symptoms, and 71 percent of participants reported that at least one symptom was new or worse than pre-injury.

A study by Dr. Michael Robinson et al., published in American Journal of Physical Medicine & Rehabilitation, used a decision tree to identify patients at higher risk of developing prolonged concussion symptoms. The researchers found that feelings of fogginess and sadness at initial assessment were predictive of prolonged symptoms “lasting 28 days or more postconcussion.”

An abstract presented at the Radiological Society of North America (RSNA) 2021 Annual Meeting demonstrated that “multiple concussions [three to five] seem to disrupt the brain’s default mode network (DMN), which could increase the risk of long-term cognitive disruption,” according to an article in Medscape.

A large-scale research project to study biomarkers that may predict delayed recovery in children and adolescents aged 11-18 was awarded $10 million by the National Institutes of Health. According to a UCLA press release, the research project (entitled CARE4Kids) will observe over thirteen hundred children and teens nationwide.