Expectations of prognosis

Psychological beliefs, such as optimism and a sense of personal control, are protective of physical and mental health in a number of medical disorders.23 Even an unrealistically optimistic view of the future helps cope with intensely stressful and life-threatening events. As found with other diseases, this finding pertains with expectations of prognosis after a concussion. When 73 patients were evaluated 3 months after mTBI, 25% had ‘postconcussion syndrome’. The beliefs about illness duration and consequences significantly predicted symptomatic outcome, above and beyond depression and post-traumatic symptoms.24 In 126 patients with mTBI who were followed for up to 6 months, predictors of having ‘PCS’ were a negative perception of having mTBI, stress, anxiety, depression and ‘all-or-nothing behaviour’ (a need to either be able to do the maximum or nothing).25 Similarly, in a group of 147 patients with mTBI who were recruited within 3 months of presenting to a concussion clinic or an emergency room, those who held stronger beliefs about the identity of having a TBI and its emotional impact had significantly greater odds of a poor outcome at 3 months.26 Psychological factors begin to impact prognosis even at the time of the injury, and may be one explanation why individuals who have suffered a concussion during sports recover quickly after an injury: they expect to fully recover and ‘get back in the game’.

Effort

A 40 year old man who had an mTBI was administered the Dot Counting Test27 as an ‘effort test.’ In this test, the patient counts dots on a card which are either randomly placed or in groups (as found in dice). The time for counting should be much faster for the grouped dots, as the individual does not need to count each dot separately. This patient counted the group dots separately, so his performance was similar in the two situations. After the test, the grouped dots were presented again, and he could easily and quickly determine the number of dots by appearance, without counting them individually. When asked why he counted the grouped dots separately during the first administration, he replied, ‘I wanted to be sure.’

‘Effort’ tests can provide important information as part of a comprehensive neuropsychological evaluation, and serve as an internal calibration for more difficult tests of attention and memory.28 ,29 These instruments are a common component of the neuropsychological evaluation, and have been described as assessing ‘cognitive exaggeration’, ‘feigning’, ‘suboptimal effort’, ‘response bias’ and malingering. Many of these tests are ‘forced-choice’, and present a series of words or pictures, and afterwards the subject is presented two words at a time, and asked which one was shown earlier. It is important to assess whether the individual is exerting optimal ‘effort’, so that we know that impairment is most likely due to the brain injury, rather than ‘not trying’. For example, if the individual only performs at or below a ‘chance’ level, it is reasonable to assume that the individual is either guessing or trying to be incorrect. However, the ‘cut-off’ for poor effort on these tests varies, and while statistically different from normal controls, it may be as high as 82.5%–90%.30–32

The context of the evaluation influences performance on these effort tests. In a study of claimants who were seeking compensation, those who had mTBI had poorer effort and worse cognitive performance than those with moderate to severe TBI.33 Nelson et al34 assessed 1991 US veterans consisting of a group referred for forensic evaluation (compensation and pension process), a group with ‘non-OEF/OIF’ (Operation Enduring Freedom/Operation Iraqi Freedom) forensic evaluations, a group with OEF/OIF research concussions (recruited to participate in ongoing research projects) and a research group without concussions. Depression and PTSD/anxiety were more common in the forensic groups. ‘Insufficient effort’ (eg, a score of <43 in the Victoria Symptom Validity Test35 or digit span <8) on at least one measure was found in 59.1% of those in the forensic groups, but only 10.7% of those in the research group. Effort accounted for 20.3%–33.5% of the performance variance in the forensic groups compared with 1%–8.4% in the research groups. In another study, individuals with severe TBI, mTBI and non-injured controls were told that test performance might affect driving ability. The group with mTBI and controls improved scores subsequent to this intervention, although controls performed better than mTBI.36

A study designed to ascertain differences in neuropsychological testing in veterans with TBI, PTSD or both highlights the complexity of interpreting reasons for insufficient effort.37 The Word Memory Test31 was administered with a cut-off of 82.5% for appropriate effort to qualify for the study. Of those screened for inclusion in the study, 0/16 of those with PTSD only and 1/26 of those with TBI only demonstrated insufficient effort. However, 15/34 of veterans with both TBI and PTSD failed the effort test and were excluded from the study. The authors did not discuss this finding. It does not make sense to say that a group of veterans were malingering or did it for ‘secondary gain’ or ‘compensation’ with coexisting PTSD and TBI, whereas veterans with either PTSD or TBI would not. We need to explore other potential explanations of increased symptom reporting, possible misattribution of symptoms to the TBI and poor effort. These are not discussed in two comprehensive consensus statements reviewing the use of an interpretation of effort tests.28 ,29

Stress and stereotype threat

Since stress and anxiety impair performance in normal subjects,38 we expect that stress affects performance and symptoms in patients with mTBI. When symptomatic individuals with mTBI were given cognitively challenging tasks, there was an increase in postconcussive symptoms and autonomic changes associated with decreased speed of processing and subtle memory deficits.39 This was correlated with a greater change in skin conductive response. We often observe athletes failing because they are trying too hard (even with an ‘easy’ task such as a short putt in golf). However, during neuropsychological testing, it is assumed that patients fail because they are not trying.

However, stress can result from another factor: stereotype threat, the observation that society's bias of a subgroup affects performance (see Steele 2010 for a comprehensive discussion).40 Stereotype threat increases the pressure to perform well under the ‘threat’ condition, and results in impaired performance (‘choking’). Examples include the effect on performance of African-Americans when given tests to assess ‘intelligence’, women math major when given a test to assess intrinsic math ‘ability’ and Caucasian men when given tests for athletic ability. Because the societal bias is ubiquitous, it may not need to be mentioned when the test is administered; the subject assumes the bias. Performance under stereotype threat is significantly impaired; when the same test is administered under conditions that eliminate the threat, performance is normal. For example, the difference in performance with and without the threat could be four out of 30 items on the Graduate Record Examination (Steele, p. 50).40 Individuals with previous educational difficulties or failure may expect themselves to perform poorly during a cognitive evaluation. The framing of a test as assessing memory rather than to gain a general impression of an individual reduces memory performance of older adults.41

Because of public awareness that brain injury produces cognitive impairment and postconcussion symptoms, stereotype threat could affect performance or the assessment of symptoms in individuals who have sustained a TBI. In this situation, the individual with a TBI will assume the bias that they will have difficulties with a cognitive task or will experience certain symptoms associated with the injury, and thus perform poorly on the task or associate symptoms with the TBI. There have been few studies of a non-clinical population (college students taking a psychology course) to assess ‘diagnosis threat’. A group of normal subjects who completed an affective, somatic and memory deficit checklist are expected to experience symptoms 6 months after an imagined concussion similar to those with the postconcussion syndrome.42 Undergraduates with a history of mTBI performed worse under the threat condition (when they participated in a study of ‘working memory in young adults who have experienced a head injury compared to young adults who have not experienced a head injury’) on attention/working memory, psychomotor speed and memory tasks (but not on effort)43 compared with the ‘non-threat’ condition (a study of ‘working memory and attention in young adults)’. In an earlier study, these investigators found that the threat group rated themselves as putting forth lower effort and had increased anxiety and vigilance. Ozen and Fernandes44 surveyed 87 undergraduates for a number of problems, including whether they ever had an mTBI. They were then asked to participate in one of two studies: either looking at ‘working memory after head injury’ or ‘working memory and attention in college students’. Under the threat, the mTBI subjects had more complaints of everyday attention problems and memory related errors. Controls outperformed subjects on one attention measure.

The theory of ‘ego depletion’ asserts that the capacity to exert self-control is a limited resource, and after a difficult task, the individual no longer has the store of normal resources and performance suffers. The ability to perform executive functions and effortful choice is affected when there are limited resources.45 Performing difficult cognitive tasks (such as the Stroop task) results in poorer performance on a subsequent task. Interestingly, increasing motivation and the provision of snacks that contain glucose can reverse the effects of depletion on performance.45 Job and colleagues found that ego depletion depends on the individual's belief as to whether it is a ‘limited resource’.46 Manipulating beliefs, such as telling a subject that doing a difficult task is energising rather than depleting, improved performance. In a study of treatments of chronic fatigue syndrome, a treatment that reinforced this belief of ego depletion (Adaptive Pacing Therapy) was the least effective treatment.47 In patients with mTBI, this is often observed during testing when patients believe they can no longer perform well on tests after a number of hours. Ego depletion may be sensitive to, or a form of, stereotype threat.

Performance under threat in a normal population (non-TBI) reduces speed and accuracy48 and working memory capacity.49 The ventral anterior cingulate cortex, which is involved in social and emotional processing, is affected during a stereotype threat.50 Patients with mTBI may respond as a ‘normal’ group, while injury to these circuits is more likely to be associated with moderate to severe injury. Hypothetically, groups with varying severity of TBI may respond differentially to stereotype threat. While stereotype threat results in a clinically and statistically significant detriment in performance for many groups of normal subjects (eg, four questions on a 30 question test), it is striking that this has never been discussed in any clinical study of symptoms, effort or cognitive performance in individuals being evaluated for the effects of TBI, or included as a possible reason for poor performance in consensus statements about effort.28 ,29 In the clinical situation, the patient is being evaluated under stereotype threat and either knows or is told that individuals who have experienced a concussion commonly experience many of these symptoms and have cognitive difficulties. Research is needed to assess this effect on patients.

Compensation and litigation

In a study of 97 individuals with mTBI evaluated 6 weeks after injury, those involved in litigation had greater anxiety, social dysfunction and poorer outcome.51 Other studies have not found an effect of litigation.7 ,21 ,22 Although it is possible that the individual ‘wants’ to do poorly to increase the potential for compensation, and some may consciously malingering, other common psychological processes may be involved. Distinct from other medical disorders, individuals who sustain a TBI are often faced with unique obstacles to treatment. Compare the individual who has suffered brain injury from a stroke to the person who has brain injury from an accident. Unlike the patient with a stroke, where treatment is instituted without doubting the veracity of the complaint, there is an independent evaluation and questioning of the occurrence of the injury and the presence of symptoms. Since TBI often occurs in an ‘accident’ setting, there is an adversarial environment between the injured and the people or insurance responsible for payment.

The legal and insurance process increases the cost (anger, revenge, loss aversion). In addition, money has an effect on behaviour for everyone involved. We would expect that those injured during sports, even on a non-professional level, would have fewer of these factors impinging on recovery. Anger, revenge and loss aversion may not be present. Most athletes expect to do well after a concussion and most do. Research in behavioural economics provides important findings that elucidate the cost of these issues. The assumption is made that the monetary cost used in these paradigms translates into symptoms.