Description of the condition

The annual incidence rates of traumatic brain injury (TBI) are rising worldwide (Roozenbeek 2013), ranging from 91 per 100,000 population, Thurman 1999, to 146 per 100,000 population (Feigin 2013). A previous review indicated that 70% to 90% of TBI cases are diagnosed as mild (Cassidy 2004). Mild traumatic brain injury (mTBI) is often determined by duration of loss of consciousness (less than 30 minutes), duration of post‐traumatic amnesia (less than 24 hours), and/or Glasgow Coma Scale score of 13 to 15 (Carroll 2004). Following mTBI, people may experience temporary physical, cognitive, and psychological symptoms (Hall 2005).

These symptoms are widely expected to resolve within three months with little or no intervention. However, early studies reported symptoms persisting for more than three months following mTBI in approximately 15% to 20% of cases (Alexander 1995). These findings have been widely cited (Alexander 1992; Brown 1994; Wylie 2015), and there is ongoing debate surrounding the prevalence, nature, and underlying causes of persisting symptoms (Bigler 2008; Iverson 2005; Larrabee 2013; Rohling 2011). Controversies aside, it is evident that a proportion of people with mTBI experience persisting symptoms that are disproportionate to their injury, and these often have a significant impact on their quality of life (Emanuelson 2003). Furthermore, long‐term symptoms (persisting for over 18 months) have been linked with high levels of postinjury unemployment, anxiety, depression, and lower quality of life (King 2011).

Current diagnostic manuals acknowledge persisting symptoms following mild to moderate TBI, although they differ in the diagnostic labels used. The International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD‐10) refers to "postconcussional syndrome", which includes headaches, dizziness, fatigue, irritability, and difficulties with concentration and memory (World Health Organization 1992). The Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM‐IV) included "postconcussional disorder" (American Psychiatric Association 2000), which was similar to postconcussional syndrome in the ICD‐10 with the additional requirement of evidence from cognitive testing. However, the DSM‐V no longer refers to these difficulties as a distinct disorder and instead describes "neurocognitive disorder due to traumatic brain injury", which does not consistently refer to the severity of injury (American Psychiatric Association 2013). The DSM‐V also acknowledges that some people who have sustained a TBI may experience persisting symptoms, which include emotional symptoms (irritability, frustration, tension, anxiety, and emotional liability), personality changes (disinhibition, apathy, suspiciousness, and aggression), and physical disturbances (headache, fatigue, insomnia, and dizziness).

The usefulness of diagnostic labels for these symptoms has been questioned (Arciniegas 2001; Boake 2004; Boake 2005). Furthermore, the variation in diagnostic criteria for persisting symptoms is also reflected in the research literature, where studies often describe and characterise persistent symptoms following TBI in different ways (Iverson 2010). Some researchers and clinicians working in the field of brain injury have been reluctant to use diagnostic labels and have described persisting symptoms that are considered disproportionate to the organic injury as "persisting post‐concussion symptoms", rather than a disorder or a syndrome (Marshall 2012).

For the purposes of this review, we will refer to symptoms commonly associated with postconcussional syndrome (ICD‐10) and persisting symptoms of neurocognitive disorder due to mTBI (DSM‐V) as persisting postconcussion symptoms (PPCS).

Assessment of PPCS following mTBI may be further complicated by the variation in assessment tools used by researchers and clinicians. Although there is no consensus about a standard assessment procedure, the Rivermead Postconcussion Symptoms Questionnaire, King 1995, and the Neurobehavioural Symptom Inventory, Cicerone 1995, appear to be used most frequently in the literature.

Given the persistent nature of these difficulties, the potential impact on family and carers should also be considered. Research indicates that family and carers of individuals who have sustained a TBI experience significant amounts of stress, depression, and emotional distress (Chan 2009). Feelings of loss, isolation, and anxiety are reported by partners of individuals who have sustained TBIs of varying severity (Liss 1990). The specific impact of PPCS following mTBI on family and carers remains unclear.

There is mounting evidence that symptoms similar or identical to PPCS often occur in the absence of TBI, including in people experiencing chronic pain (Iverson 2005; Smith‐Seemiller 2003), psychological difficulties (Ruff 2011), and in healthy individuals (Chan 2001; Donnell 2012; Iverson 2003; Waljas 2015). This may reflect the existence of general psychological mechanisms contributing to the development and maintenance of PPCS. Hence, it has been hypothesised that psychological interventions may be able to prevent the development or maintenance of PPCS following mTBI, or to treat postconcussion symptoms that have already become persistent.

Description of the intervention

The available evidence consists of studies evaluating a number of different psychological interventions for the cluster of symptoms that people may experience as PPCS. These studies can be divided into two groups: those that aim to prevent the development and maintenance of PPCS immediately following mTBI, and those that aim to treat postconcussion symptoms that have become persistent. The aim of the current review is to evaluate the evidence for the latter group of studies.

Interventions for persising postconcussion symptoms have mainly involved psychoeducation, psychotherapy, cognitive strategies, and counselling.

• Psychoeducation provides individuals with information about their condition and any associated difficulties they may experience.

• Psychotherapy interventions support individuals to manage their psychological difficulties and modify behaviours. Examples of psychotherapies include cognitive behaviour therapy, mindfulness‐based therapies, compassion‐focused therapy, and acceptance and commitment therapy.

• Cognitive strategy interventions engage individuals in exercises that aim to improve cognitive functioning. They may also include compensatory strategies intended to reduce the impact of cognitive deficits, such as the use of external memory aids.

• Counselling interventions allow individuals to talk about their problems and feelings in a confidential and dependable environment.

How the intervention might work

The overarching objective of psychological interventions for PPCS is to reduce psychological distress and to promote psychological and cognitive strategies that will improve the individual's level of function and reduce symptoms.

• Psychoeducation interventions improve knowledge and understanding of the target condition. This may empower individuals, giving them a greater sense of control over their condition and defusing negative stereotypes.

• Psychotherapies employ psychological methods to support individuals to overcome difficulties in a desired way. The aim of psychotherapy is to increase psychological well‐being and modify unhelpful behaviours, thoughts, and beliefs.

• Cognitive strategies are generally divided into two different categories: restorative interventions, which aim to improve cognitive functioning through repetition and gradually increasing demands; and compensatory strategies, which aim to reduce the negative impacts of cognitive difficulties through reducing reliance on areas of cognitive deficit.

• Counselling allows individuals space to reflect and discuss their experience in order to reach their own understanding of what is happening. This may also empower individuals with a greater sense of control over their experiences.

Why it is important to do this review

People experiencing PPCS may present to a variety of services including primary care, community brain injury, and mental health services. The complex and clinically challenging nature of this presentation can place a significant burden on family and friends, healthcare providers, and insurers (Wood 2004). There are also economic implications: return‐to‐work rates are poor (King 2011), and there are often issues around litigation (Tsanadis 2008). Despite this complexity, research exploring the effectiveness of interventions specifically for PPCS has been limited, and there is no consensus about appropriate and effective interventions for this phenomenon. This may be due in part to the confusion around the aetiology and maintaining factors of PPCS being translated into a vague and uncertain picture of care.

There are currently no clinical measurements that are known to predict which individuals will experience poor outcomes following mTBI (Arciniegas 2005), and current National Institute for Health and Clinical Excellence guidelines for brain injury make no reference to PPCS, with little mention of mTBI (NICE 2014). This may be due in part to limited evidence on what interventions are most effective.

Two previous reviews investigated the effectiveness of rehabilitation interventions following mTBI (Ponsford 2005; Snell 2009). Both reviews found little available evidence for the management of mTBI, which was generally of poor methodological quality, and concluded that there was a need for more research into the management of symptoms following mTBI. Sayegh 2010 reviewed the evidence for psychological interventions specifically aimed at PPCS and drew similar conclusions. Sayegh 2010 found few high‐quality studies investigating interventions for PPCS and included studies that had significant methodological weaknesses, and concluded that cognitive behavioural interventions appeared to show some consistent benefits, while psychoeducation approaches showed mixed results.

A systematic review of the recent literature may identify which interventions are most effective, or show most promise, in reducing PPCS. This information would be useful for guideline producers, policymakers involved in developing services for people experiencing PPCS, and people interested in identifying promising research directions.

The purposes of this review are (a) to clarify the evidence base to enable commissioners, clinicians, and patients to make appropriate clinical decisions, and (b) to inform the development of further randomised controlled trials investigating psychological interventions for PPCS.