E-27 cognitive deficits
In 2005, Peter Halligan and I published The Effectiveness of Rehabilitation for Cognitive Deficits, a book reviewing all aspects of the topic. I referred to the biopsychosocial model as the WHO ICF framework at that time. In my chapter, Applying the WHO ICF framework to the rehabilitation of patients with cognitive deficits, I argued one should focus on improving function, not improving the impairment. I still believe this must be the focus of rehabilitation. Nonetheless, to be competent, one must learn how to recognise when a cognitive loss is contributing to a functional limitation and how it is vital to recognise some of the rare defects that may be misinterpreted as psychiatric disorders, such as confabulation or Anton’s syndrome. Some people assume that cognitive impairment, especially amnesia, makes rehabilitation fruitless. This is untrue; one can still adapt and learn using environmental cues and adaptations, learning through repetition, and learning procedures.
Table of Contents
Cognitive deficits: the competency
The rehabilitation expert should “be able to assess general cognitive functioning, including different domains, and able to set out a strategy for further investigation and management.” The behaviours that indicate competence in managing patients with cognitive deficits and some references are shown in a downloadable document.
Introduction
“Cogito ergo sum”, I think therefore I am, must be one of the most famous philosophical arguments. It should thus be no surprise that most people value their cognition highly and fear losing it; as evidenced in people with severe dementia, the loss of coherent thinking is associated with the loss of personal identity. I have discussed personal identity in a blog post on personal factors in rehabilitation.
Cognition is “the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses”, according to the Oxford English Dictionary [OED]. Still, most clinicians refer to individual cognitive functions. The classification and separation of these functions are arbitrary because the brain works as a whole, not with a group of individual functions. While similar groups of function are recognised widely, there are also many differences. Philip Harvey has published one categorisation of domains of cognition, which is reasonably representative. Aayush Dhakal and Bradford Bobrin have published a brief overview of cognitive deficits.
The classifications used, and the localisation of some deficits to some localised areas in the brain give many professionals and most patients the impression that a deficit is limited to one specific function. This is rarely true. Dramatic examples of striking deficits such as prosopagnosia (the inability to recognise different faces) or severe left-sided visuospatial neglect foster this impression.
Reality is much more mundane. Cognitive deficits are rarely, if ever, seen in isolation and are often combined with impaired motor control and emotional disturbances. Emotional disturbance can affect cognitive function directly, and both can influence the accurate assessment of cognitive abilities.
Cognitive deficits: evidence.
There is extensive evidence showing the occurrence of cognitive dysfunction in many neurological conditions; I will not give any here. However, cognitive dysfunction can be seen in disorders less likely to cause it. For example, cognitive dysfunction is seen in some people with motor neurone disease, including people with primarily lower motor neurone losses (i.e. progressive muscular atrophy). There is an overlap between motor neurone disease and frontotemporal dementia, with some people in the middle of the spectrum.
Purely muscular disorders are also associated with cognitive deficits. For example, Duchenne muscular dystrophy is associated with cognitive impairment. The explanation is that the genetic abnormality also affects proteins in the brain. Cognitive deficits are also frequent in people with facioscapulohumeral dystrophy, and the severity correlates with the generic molecular defect.
Keith Cicerone and colleagues have published several systematic reviews, concluding that it is effective for:
- Attention deficits
- Visual scanning as a technique to overcome visuospatial neglect
- Mild memory deficits (compensatory techniques)
- Language loss after stroke
- Social-communication deficits after traumatic brain injury
- Metacognitive strategy training when executive functions are disturbed.
However, Caroline van Heugten and colleagues reviewed 95 trials published between 1980 and 2010, and very few studies gave any information about the content of the intervention studied, which makes it challenging to offer treatment based on evidence. (Competing interest: I was one of the authors.)
The optimistic conclusion by Cicerone et al. contrasts starkly with the findings of Cochrane systematic reviews. For example, in 2019, Tobias Loetscher et al. concluded, “The effectiveness of cognitive rehabilitation for attention deficits following stroke remains unconfirmed. The results suggest there may be an immediate effect after treatment on attentional abilities, but future studies need to assess what helps this effect persist and generalise to attentional skills in daily life. Trials also need to have higher methodological quality and better reporting.”
Another Cochrane systematic review of cognitive rehabilitation for people with traumatic brain injury in 2017 by Suresh Kumar et al. concluded, “There is insufficient good‐quality evidence to support the role of cognitive rehabilitation when compared to no intervention or conventional rehabilitation in improving return to work, independence in ADL, community integration or quality of life in adults with TBI.”
The last example (among others) is the review by Roshan das Nair et al. in 2016, which investigated cognitive rehabilitation for memory deficits after stroke. They concluded, “Participants who received cognitive rehabilitation for memory problems following a stroke reported benefits from the intervention on subjective measures of memory in the short term (i.e. the first assessment point after the intervention, which was a minimum of four weeks). This effect was not, however, observed in the longer term (i.e. the second assessment point after the intervention, which was a minimum of three months). There was, therefore, limited evidence to support or refute the effectiveness of memory rehabilitation.”
The most recent scoping review in February 2023 into Cognitive Rehabilitation After Moderate to Severe Traumatic Brain Injury by Adeline Julien and colleagues found 46 new trials since the 2015 review by Cicerone. Still, only seven of these were of high quality.
One cannot conclude that cognitive rehabilitation is effective in ameliorating cognitive impairment because:
- There is limited or no record of the interventions given, so one cannot replicate the intervention;
- Although immediate effects have been found, long-term effects are either not studied or, when studied, are not found;
- The methodology (design, execution, reporting, measures used) of many studies is not of sufficient quality
Interventions are better aimed at improving function rather than performance on measures of cognitive function. Environmental changes, such as using whiteboards and smartphones, are more likely to help than using practice at cognitive tasks.
Assessing cognition
There are innumerable tools that screen for cognitive impairment. The Mini-Mental State Examination is the best known, though the Montreal Cognitive Assessment is superior as a routine screening tool. A systematic review supports this conclusion.
The primary skill needed in rehabilitation is always to consider whether cognitive impairment is present and, if so, whether it affects function. Put more practically, if a person develops a problem undertaking an activity and no apparent other cause is identified, one must consider cognitive impairment. Cognitive impairment usually affects more complex tasks first, but one must realise that routine daily tasks, such as dressing and cooking, require significant cognitive input.
A detailed assessment of all cognitive functions can take many hours. This time is rarely available, and most patients cannot tolerate such intense assessment. Self-reporting cognitive function is one approach, and an item bank of questions showed a close correlation with abilities.
Proxy reporting (i.e. information from a family member or friend) is another avenue. Angélique Gruters and colleagues found that proxy reporting correlated well with testing, but in a population of people with dementia, self-reported cognitive decline was also correlated with depression. Robert Spencer and colleagues also found an association between emotional impairments and self-reported cognitive deficits in a population of people after mild head injury; there was no correlation with measured cognitive ability.
In everyday practice, detailed assessment should be reserved for people where knowing the details will alter decisions. Usually, the clinical psychologist’s time would be better spent considering and implementing policies to improve function or safety.
Assessment of a person’s mental capacity to make decisions may require formal assessment occasionally. However, no formal assessments can determine a person’s mental capacity to make a decision, not least because the judgement is issue-specific. I have reviewed the evaluation of mental capacity, and the article will give more information and guidance.
Interventions
The General Theory of Rehabilitation defines the most effective interventions as catalytic rehabilitation actions. They involve a complete analysis and formulation that identifies that cognitive deficits are causing or exacerbating a clinical problem. The primary solution is often to explain this to the person and their family and to give advice on ways to manage it. For example, one may advise using diaries and other memory aids if someone is forgetful or that communication is slower if the person has a reduced speed of information processing.
One may suggest practising strategies or structuring the activity in other ways for complex behaviours to reduce the cognitive demand. A clinical psychologist or other expert (e.g., occupational therapist) will usually help in each case.
Conclusion
The safety and quality of activities undertaken by a patient with neuromuscular disease are commonly affected by cognitive impairments. The single vital skill of a rehabilitation expert is to consider whether cognitive dysfunction affects a person’s social or physical functions. This requires vigilance based on an awareness of how cognitive dysfunction might affect the performance of a task. Familiarity with basic screening tests will help, but the results should be interpreted cautiously. Abnormality may not indicate cognitive impairment but may be due to depression or be expected for that person.
Conversely, normality does not exclude a considerable reduction in cognition for the individual. The evidence on the effectiveness of interventions must be reviewed critically, and most efforts should focus on helping the person and their family adapt and function despite the impairment rather than expecting to reverse it. Last, impairment in one domain usually implies some impairment in other domains.
