New Research Shows Mild Traumatic Brain Injury Symptoms Can Persist for Years

For many years, patients who sustained a mild traumatic brain injury, often referred to simply as a concussion, were told that their symptoms should resolve within a few weeks or months. A new longitudinal study published in Brain Injury, however, reinforces what many survivors and clinicians already know: for a substantial number of people, these symptoms do not simply fade away. They linger—often for years.

The study followed 142 adults who were hospitalized after a mild TBI and assessed them repeatedly over a four-year period. At every checkpoint—four, eight, twelve, twenty-four, thirty-six, and forty-eight months after injury—at least forty-five percent of participants continued to report three or more clinically significant symptoms. This is a striking finding because it directly contradicts the commonly quoted expectation that concussion symptoms should dissipate within the first three months. The most persistent and prevalent symptoms were fatigue, insomnia, and cognitive complaints, each of which affected more than half of participants throughout the study. Other symptoms such as anxiety, depression, headaches, and dizziness often emerged in combination with these core difficulties.

The presence of multiple symptoms had a profound effect on daily life. Individuals who reported three or more symptoms consistently scored in the “poor” range on validated quality-of-life measures. Their ability to participate in social roles and everyday community activities declined in parallel with their symptom burden. The impact on work was particularly significant. Four years after injury, participants who had no ongoing symptoms had returned to work at rates exceeding ninety percent. In stark contrast, those with five to seven symptoms had return-to-work rates hovering around twenty-eight percent. These numbers powerfully illustrate how persistent post-concussive symptoms can derail careers, independence, relationships, and overall well-being long after the initial trauma.

Perhaps even more concerning is the pattern of diminishing healthcare access over time. Early after injury, most individuals with a high number of symptoms were receiving specialized care. By thirty-six to forty-eight months post-injury, however, only about half of those with the most severe symptom burden continued to receive treatment. This decline may reflect cost, insurance limitations, limited access to specialty care, or simply the mistaken belief that nothing more can be done.

The findings of this study highlight a crucial shift in how mild TBI should be understood. Symptoms that persist beyond the first few months are not rare outliers; they are a common reality. Recognizing the significance of ongoing symptoms is essential, not only for clinicians but also for families, employers, and legal professionals. A threshold of three or more symptoms was consistently associated with diminished quality of life, reduced social participation, and lower return-to-work rates. This makes it a meaningful indicator of when individuals may require comprehensive, interdisciplinary support.

Ultimately, this research underscores the importance of long-term care for concussion survivors. A “mild” brain injury can carry severe, life-altering consequences. Many patients continue to struggle years after their injury, often without appropriate treatment. Understanding the long-term nature of these symptoms is critical in ensuring that individuals receive the care, recognition, and support they need. For survivors who continue to experience persistent symptoms, it is essential to know that recovery timelines vary widely and that the persistence of symptoms does not reflect personal failure. It reflects the reality of an injury whose effects can be far more enduring than commonly understood.

This article incorporates findings from Cairns et al., “Symptom burden in the first four years following hospitalization after mild traumatic brain injury,” Brain Injury (2025).