How does an ADHD diagnosis impact personal injury and clinical negligence claims?

Attention deficit hyperactivity disorder (ADHD) is a common condition, affecting around 5% of children. However, this is likely to be an underestimate as diagnosis rates are low. It is characterised by periods of inattention, hyperactivity and impulsivity, which are severe enough to interfere with daily functioning. In most patients, the symptoms start before the age of 12, leading to the traditional belief that ADHD is a childhood condition, although nowadays, it is increasingly being recognised that symptoms can persist into adulthood. ADHD can be managed though lifestyle adjustments, changes at school or work to accommodate the patient’s condition, and medication.

In the UK, if certain criteria are met, ADHD can be recognised as a disability under the 2010 Equality Act. Therefore, its presence should not preclude an individual from launching a legal case following personal injury or medical negligence. However, ADHD can complicate the process and there are several issues to be aware of. It can be much more difficult to get consistent evidence from a patient with ADHD, due to lack of attention and memory span. In severe cases, this may lead to the limitation period during which litigation must be commenced to be extended from the usual timeframe of three years. Should a case come to court, ‘necessary adjustments’, including more rest breaks, may have to be made so that the patient can participate as fully as possible in the legal process.   

If a case is successful, the presence of ADHD can significantly affect the level of damages awarded. Where a patient with a pre-existing neurological condition like ADHD subsequently suffers an injury such as a traumatic brain injury, disentangling the effects of the two conditions can be extremely challenging. It is even more difficult in young patients, where the brain is still developing and it is unclear how they would have performed in the future if the injury had not occurred.

In almost all such cases, the defendant will try to claim that the pre-existing ADHD will impact the patient’s future progress more than the injury caused by their negligence. Reports from a number of experts, including neurologists, neuropsychiatrists, neuropsychologists and educational psychologists, may be required to make a reasonable prediction of the patient’s prognosis, both with and without the injury. While ADHD often negatively affects a patient’s educational achievement and ability to work, a brain injury may increase their vulnerability further, leading to a worse outcome. Similar problems are encountered when existing ADHD symptoms are exacerbated by the accident or injury, and robust evidence is required to distinguish between pre-existing and new symptoms. Any rehabilitation requirements that relate specifically to new or exacerbated ADHD symptoms can be added to the claim.

The issue of liability is complicated by the fact that individuals with a diagnosis of ADHD experience higher rates of unintentional and accidental injuries. They also suffer from higher levels of morbidity and mortality following these incidents. This risk is associated with the age of the patient, peaking in children aged 9–12 years and again in adolescents aged 18–25. Although the type of accident or injury also changes with age, this appears to be due to the situational nature of these incidents. Thus, the increase in driving-related incidents in older patients merely reflects the fact that only adults are allowed to drive.

The mechanisms behind the increased risk of accidental injury are not clear. There is some evidence implicating the core ADHD symptoms of inattention, hyperactivity and impulsivity, but other factors, including daytime sleepiness, psychosocial stress and driving while under the influence of drink or drugs may also play a role.  Comorbidities, such as mental disorder, conduct disorder, oppositional defiant disorder, antisocial personality disorder, depression, autism spectrum disorder, reading disability and adolescent substance or alcohol abuse are also risk factors for accident and injury risk.

The persistence of ADHD symptoms into adulthood further increases the risk of accidental injury. In addition, the risk of death is higher in patients diagnosed in adulthood compared to childhood. This suggests that adult ADHD represents a more severe form of the condition. In contrast, ADHD medication has been shown to lower the risk of accidental injury and this effect does not appear to be dependent on age. However, the beneficial effects of medication on injury risk are less prominent in female patients.

ADHD is associated with longer recovery times following accidents and injuries, although this finding is not universal and has been disputed in the scientific literature. Multiple studies have reported that patients with ADHD take longer to recover from concussion than neurologically normal patients. Furthermore, post-concussion testing reveals differences in neurocognitive and psychological parameters in the ADHD population, who are at higher risk of experiencing undetected post-injury symptoms. Thus, understanding the impact of ADHD on specific measures of concussion may assist in interpreting the results of clinical tests and ensuring appropriate care. However, claiming increased recovery times due to the presence of ADHD remains controversial.

ADHD impacts on claims for personal injury or medical negligence in several ways. In particular, the increased likelihood of injury or accident in this population complicates the issue of liability. Increased recovery time and specialised rehabilitation needs may add to the amount claimed. However, none of these factors should preclude a patient with ADHD from making a claim if it is justified.