Each year, over 1 million people attend emergency departments in England and Wales with a recent head injury, otherwise known as a traumatic brain injury (NICE, 2023). Traumatic Brain Injury (TBI) is defined as ‘any change in brain function resulting from an external force, such as a blow or injury to the head, accelerating/decelerating movement, and forces generated from blast events’ (Ogonah et al., 2025). Statistics presented in the NICE guidelines (2023) show that TBIs are a major cause of death and disability in people aged 1 to 40 in the UK; making this topic a crucial one to research and further understand.

The health outcomes of TBI can be severe and long-lasting. Research into the quality of life following a TBI (Polinder et al., 2015), disability, physical and mental health consequences of TBI (Jourdan et al., 2018; Howlett, Nelson & Stein, 2022) capture some of the impacts of this condition. For example, Jourdan et al.’s (2018) survey demonstrates that the TBI population have higher rates of cardiovascular, respiratory, musculoskeletal, digestive, urological, neurological, and psychiatric conditions than the general population. Howlett, Nelson & Stein (2022) outline how moderate and severe TBI can cause personality changes, whilst mild TBI is associated with suicidality, post-traumatic stress disorder and major depressive disorder.

Multiple studies call TBI a chronic health condition with lifelong and dynamic effects on health and wellbeing (Corrigan & Hammond, 2013; Wilson et al., 2017; Corrigan & Hammond, 2013). Mental Elf bogs by Holloway (2018), Mantell (2019) and Kennedy (2016) also discuss the “bio-psycho-social” conditions that affect every aspect of lives and daily living activities (Holloway, 2018).

All this evidence demonstrates why Ogonah et al.’s review is so important. The authors state that previous studies on this topic focus on single, acute conditions or diseases immediately following TBI, whilst they examine long-term health outcomes in different severities of TBI—mild, moderate and severe—an overview that is missing from the literature.

In their recent study, Ogonah and colleagues (2025) use an umbrella review methodology to evaluate the wide range of physical and mental health outcomes that occur in people following a traumatic brain injury (TBI). The authors examine the risks of having these outcomes across subpopulations (children/adolescents, sports-injured, military or veterans, older adults). This paper presents a synthesis of existing review evidence from more than 31 million participants, aiming “to help quantify the overall disability burden from TBI in order to inform targets for clinical and policy interventions”.

Methods

The authors respond to the question: What is the current evidence for the association between traumatic brain injury and adverse health outcomes? They proceed with a database and manual search of existing systematic reviews, evaluating the condition or domain of adverse health outcomes (physical and mental health) and mortality.

This umbrella review follows a JBI methodology which is an evidence-based tool for evaluating scoping reviews (Aromataris et al., 2020: 364-410). This methodology allowed the authors to assess evidence-based healthcare by considering the feasibility, value and effectiveness of healthcare practices in the systematic reviews they examine.

The search strategy collates and evaluates information from existing systematic reviews and meta-analyses of studies on health outcomes following TBI. A keyword search was conducted on electronic databases for papers, including grey literature. The inclusion criteria were systematic reviews and meta-analyses; the population was individuals who have experienced TBI plus control groups or pre-TBI measurements, including adverse health outcomes after a TBI.

Following data extraction, the methodological quality of each systematic review and meta-analysis was appraised with AMSTAR 2 (A Measurement Tool to Assess Systematic Reviews). Data was converted to risk rations, giving risk estimates of the 24 health outcomes for mild, moderate and severe TBI (and all TBI). A narrative synthesis of findings in each of the 24 papers, assessing TBI and health outcomes across severity and vulnerable subpopulations. The research design, protocol and supplementary information are published alongside the main paper.

Results

The search identified 8,028 articles, and 325 studies were selected and screened as full text papers. In total, 24 systematic reviews and meta-analyses were eligible, including 24 mental and physical health outcomes of TBI, drawn from a total of 31,397,958 participants.

The umbrella review engages with a large quantity of data to assess many consequences of a TBI. These include physical health outcomes such as epilepsy, stroke and amyotrophic lateral sclerosis (a nervous system disease that affects nerve cells in the brain and spinal cord); and mental health outcomes, such as psychosis, attention-deficit/hyperactivity disorder, suicide, post-traumatic stress disorder and depression.

The authors’ findings of relative risk by subpopulation demonstrate that particular groups of people are more likely to be affected by certain health conditions following TBI, when compared to people who do not have TBI. The authors posit the level of risk for getting different illnesses after a TBI, depending on the severity of the TBI. This evidence is compelling. For example, children/adolescents with severe TBI have an increased risk of ADHD and there is an increased risk in the same population, who have a TBI of any severity, of having psychosis. In older adults, there is a significant link between TBI and Parkinson disease. In veteran populations, mild TBI is associated with a higher prevalence of chronic pain (compared with non-TBI veterans). Children are more likely to have PTSD and gait impairment following TBI, compared with control groups without TBI. The authors note that there is a lack of review evidence on adverse outcomes in survivors of intimate partner violence.

Population attributable fractions (PAF) for TBI are estimated, as measures of how many cases of a health outcome could be prevented if TBI were eliminated. PAFs are used to identify risk factors for disease and to inform public health decisions. The study uses PAFs to show how much a TBI contributes as a modifiable risk factor to developing conditions such as dementia (7.3%), epilepsy (27.5) or stroke (11.3%). This risk is different according to subpopulations and TBI severity (see table S4).

The methodological quality of each review giving these outcomes is also assessed using AMSTAR, showing varying levels of rigour. In particular, three health outcomes for people with TBI —dementia, violence perpetration, and amyotrophic lateral sclerosis—have meta-analytical evidence of moderate to high quality. This makes these specific results more reliable. But AMSTAR crucially reveals that of the 24 reviews here considered, 2 (8.3%) were moderate, 3 (12.5%) were low, and 19 (79.1%) were critically low in terms of quality. None were rated as high quality. Where does this level of quality leave the conclusions of this review?

Conclusions

This umbrella review concludes that TBI increases the risk of adverse health outcomes. The authors emphasise the range of quality in research about TBI and health outcomes, informing readers to consider the findings with a pinch of salt. However, it is important to note that this study leans on the higher quality of evidence in the reviewed papers, demonstrating an increased risk of dementia, violence and amyotrophic lateral sclerosis following TBI. The review demonstrates the need for further awareness about the long-term consequences of TBI, beyond the initial impact and intensive, hospital care. The authors conclude:

TBI should not only be regarded as an acute condition but can be a chronic disease associated with long-term health outcomes, negatively impacting quality of life. Public health and policy awareness of the extent, range, and severity of the consequences caused by TBI can inform service development. Furthermore, health-care services should review their approaches to prevent these longer-term consequences.

Strengths and limitations

The strength and innovation of this review is its umbrella methodology. This is not a single study, but an overview of many studies, assessing and evaluating multiple health outcomes from TBI. Several other studies also examine the long-term effects of TBI (Andelic et al., 2016; Stocchetti & Zanier, 2016; Masel & DeWitt, 2014), although they do not use the umbrella methodology. One example, Haarbauer-Kruper et al. (2021)’s ‘Epidemiology of Chronic Effects of Traumatic Brain Injury’, analyses the long-term outcomes of different severities of TBI, concluding (similarly to Ogonah et al.) that there is little research into multiple long-term consequences and much existing research is methodologically flawed.

The umbrella review engages with participants who have sustained specifically traumatic brain injury, rather than acquired brain injury (ABI). ABI is a more general term to TBI, including non-traumatic brain injuries such as stroke, tumour or infectious disease REF. It would be interesting to expand the study and consider systematic reviews or meta-analyses that include studies of participants who have sustained a non-traumatic brain injury.

This review addresses a clearly focused question and, as an ambitious study, it examines a large body of work about TBI and health outcomes. The assessment of quality reveals weaknesses in the field of research about TBI outcomes, which threatens to challenge the strength of the study’s conclusions, raising doubts about the precision of the results in the papers here examined. But revealing this vulnerability and the needs of the field is an important finding and should prompt further, stronger research. There is limited rigorous research in TBI, calling for the work being done in this paper. Everyone agrees—new approaches are needed.

The authors state that their methodology of assessing quality and limitations in the reviews poses its own limitations. We find meta-limitations (limitations in assessing limitations). The quality assessment (AMSTAR) tool, used to evaluate systematic reviews of randomised trials, is less accurate when used to assess reviews of observational studies. The authors responded to this by including other measures of bias, to expand and back up their evaluation of quality.

Before we get tangled up in technical problems at the heart of biomedical research, in a field where so much is unknown, it is important to grasp the strengths of this study. It sources multiple health outcomes from TBIs of varying severities, in a number of different subpopulations. We learn about the likelihood of developing certain diseases or conditions changes, according to the severity of TBI, differing for young people, war veterans, elderly, etc. Even if the methods used by the papers which present this evidence are to some extent flawed, Ogonah et al. bring together a wealth of valid data and information about what happens in the long-term, after a brain injury. This study shows us how substantial the burden of disease is, following TBI, which will support more long-standing treatment interventions in the future.

Implications for practice

The review states that it opens new directions for clinical practice, by suggesting that longer term treatment is important after a TBI, to prevent adverse outcomes. This important point needs to be taken into account clinically and in social care, although the review does not give specific ideas about how or where to instigate these changes.

It is a difficult task to support “the complex paths and wide range of outcome domains following head injury” (Ogonah et al., 2025), as so much is still unknown. I had a TBI when I was 18 years old. Twenty-five years later, the consequences of this injury still affect me. My experience of TBI is “a chronic disease process”, an ongoing “lifelong process” (Masel & DeWitt, 2010). I was given medication and therapy and other forms of treatment, but the only thing I was ever really told would fix this process was rest. The doctors said to me, “Go to sleep”. In the meantime, my identity had eroded in total amnesia, with dire consequences. This complex situation had no solution in medicine.

But the review states that:

Precision medicine approaches to TBI management can assist in better outcome prognosis and appropriate targeting of treatments and other health-care resources.

Precision medicine works with individual variability in genes, environment and lifestyle, laying biomarkers for treatment in therapeutic decision-making, multimodal neuromonitoring, and genomics (Cruz Navarro, Ponce Mejia & Robertson, 2022; Sinclair, 2024). Precision medicine currently seems an expensive, not immediately accessible solution for supporting people to have better health outcomes after TBI. Engaging with creative health methods (for instance, art, nature, community assets) has proven to have positive effects for people who have TBI of any severity (e.g. Wolf & Rattigan, 2024; Di Vita et al., 2020). The project I lead, A Creative Transformation, works for and with survivors of brain injury to support a notion of recovery that means living well with what we already have, namely our damaged brains.

Ogonah et al.’s review goes some way to lay a bridge over the vast hole of not-knowing about the consequences of TBI. It gives us more information about long-term adverse health effects and demonstrates that even more work still needs to be done to support people with them. People who have experienced TBI, including myself, need wider opportunities to experiment further with creative methods and connect with other survivors. We also need stronger and more robust science to build new healthcare services and change outcomes.

Statement of interests

Lorna has lived experience of mental health difficulties and a traumatic brain injury. No conflicts of interest to declare concerning the study.

Links

Primary paper

Ogonah, M.G.T., S. Botchway, R. Yu et al. (2025) ‘An umbrella review of health outcomes following traumatic brain injury’ in Nat. Mental Health 3 83–91. https://doi.org/10.1038/s44220-024-00356-5

Other references

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