This blog for our special series on #LifeAfterStroke is for anyone interested in cognitive rehabilitation after stroke. Neuropsychologist Marta Bienkiewicz, takes a look at what we know about its effectiveness.
Page last updated 5 July 2021
I remember, as a child, being confused as to why my neighbour, who was a neurosurgeon, had to not only stop working, but could not longer even hold a conversation. I knew something had happened; I just was not sure what. Now as a neuropsychologist I understand it well.
Every two seconds someone in the world has a stroke (Feigin et al., 2010). These harsh statistics should concern everyone. Stroke strikes both mental and physical health with a similar gravity. Overnight, a person affected has to face new limitations in mobility and cognition, and adapt to them. This blog is about how stroke may impact cognitive brain function and what the scientific evidence to date says about the available treatment options.
The complexity of the brain
We live in an era of rapid scientific developments, including neuroscience, yet the functional architecture of the brain is still a puzzle. Scientists usually describe cognitive functions of the brain globally for example as the ability to think and steer behaviour. Those functions encompass: speech, being able to switch between tasks, organising behaviour (executive functions), memory, attention and the ability to use symbols and tools.
What is known for sure is that when a stroke strikes – due to blocked blood supply or haemorrhage – part of the brain is irreversibly damaged. What is more of a gamble is what happens afterwards. The loss of function caused by neuronal death in one area can be remedied by another site if it will accept remapping of the neurons from its neighbours. Then the lost function can be partially restored, or alternatively, compensated for by effortful strategies.
The extent to which post-stroke recovery happens spontaneously, or can be aided with one-to-one rehabilitation, remains unclear and seems to vary from person to person. Let’s look into the evidence provided by Cochrane Reviews on this topic.
Speech therapy: what does the evidence say?
Loss of ability to speak and understand speech (dysarthria and/or aphasia) is one of the most striking and frequent consequences of stroke, which on average occurs in one in three survivors. Lack of ability to communicate is extremely debilitating, and even when speech problems after stroke are less profound than other effects, they may matter just as much, or more, to the person affected. Caroline Carus makes this very clear in her blog for this series about her own experience of life after stroke, as does Annette in this earlier blog, where she writes about her life with dysarthria.
Imagine that you wake up in a world where all of a sudden you cannot comprehend or use your mother tongue (aphasia) or articulate and deliver speech (dysarthria). Although treatment of aphasia varies across countries, it is usually delivered by a trained speech therapist, not an occupational therapist or neuropsychologist. In a Cochrane Review (Brady et al., 2016) of aphasia treatment, authors found that speech and language therapy (SLT) may improve functional communication significantly in people with aphasia, in comparison to no intervention or a non-structured one (such as exposure to social setting). Authors highlighted the finding that the most efficient treatment was delivered at high intensity, high dose, or over a long duration. Interestingly enough, in a Cochrane Review (Elsner et al., 2015) looking at SLT in combination with transcranial direct current stimulation (tDCS) – hype of the last decade – authors did not find evidence that adding tDCS was any more effective that SLT alone. [Editor’s note: this review was updated in May 2019 and the review authors say that “there is limited evidence that tDCS may improve naming performance in naming nouns (moderate quality of evidence), but not verbs (very low quality of evidence) at the end of the intervention period and possibly also at follow‐up.”]
In another Cochrane Review, Mitchell et al. (2017) found no adequately powered interventions to provide evidence to support efficacy of dysarthria rehabilitation.
The mental planner and its sibling, attention
Cognition is the very core of our mental ability to plan, solve and monitor our behaviour in a purposeful way and respond in an adequate way to new situations. Those functions are referred to as executive functions and they emerge from a wide brain network. Often in case of a stroke, even if resulting brain damage is not that extensive, those functions are in effect compromised.
During neuropsychological therapy for restoring some of those functions, people are guided to divide tasks they could do before, without thinking, into portions of information they can handle. For example, toothbrushing requires first wetting the toothbrush before adding toothpaste. This can be rehearsed at home with verbal cues. But how efficient are those interventions? The Cochrane Review conducted by Chung et al. (2013) demonstrated that there is still insufficient high quality evidence to support the use of such training of executive functions over no training, placebo or sensorimotor training (training involving motor and sensory tasks with the affected side of the body).
Sometimes, it is hard to pinpoint whether the difficulties are indeed related to executive dysfunction or related to an inability to sustain attention. The two are hard to disentangle. For example, a person might forget to put water in the kettle when making a cup of tea, but it is not necessarily related to a lack of knowledge as to how to organise the action, but rather could be due to distraction. We have all done it, but this may become a much more common problem after a stroke.
It is estimated that attentional deficits affect one in two to four patients at the time of discharge from the hospital (Hydmann, 2008). A Cochrane Review of the cognitive rehabilitation of attention deficits (Loetscher et al., 2019) also reported no evidence for the efficacy of cognitive rehabilitation in treatment of attention dysfunction [the review was updated in 2019 with no changes]. This includes disruption in ability and readiness to respond and focus on specific stimuli, maintain attention after period of time and attend to all sides of the space.
The same review found that training may improve performance in tests of divided attention, but is not transferable to improvement in daily functioning or long term test performance. Similar results were reported by another Cochrane Review (Longley et al., 2021), which targeted a major symptom in post-stroke survivors – spatial neglect. Spatial neglect stands for a difficulty in attending to one side of space (visual, auditory or tactile) despite full sensory capacity. Authors also found that the evidence is very uncertain about the effects of cognitive rehabilitation.
A walk down memory lane
The Cochrane Review (das Nair et al., 2016) of cognitive rehabilitation for memory deficits after stroke looked at the interventions aiming to boost memory functions. No long term objective memory improvement was found. However, there was some evidence for immediate enhancement in subjective memory assessment post-intervention in one large study. So people felt they are doing better in daily life. Does that matter? In terms of personal happiness – yes. In terms of putting resources put into maintaining such treatments – this perhaps, is a subject of debate.
It is very common after stroke for people to find that they have difficulty using everyday tools, such as cutlery. Although to date there is no Cochrane Review addressing this particular deficit, it affects daily life as much as the other deficits discussed. Apraxia and Action Disorganisation Syndrome describes the inability to use tools in a purposeful manner and carry out complex multi-step activities, such as making a sandwich or cup of tea. It affects half of all first-time stroke survivors, and can become chronic in a quarter (Bickerton et al., 2012). In a Cochrane Review by Bowen et al. (2013), evidence from three studies is presented, which shows an immediate post-intervention effect of cognitive rehabilitation, but this did not transfer to daily life functioning or long term improvement. Similarly, Worthington (2016) concluded that while strategy training may be promising for training task-specific tasks, the future might lie in the intelligent assistive devices that create prompts for people at home during daily tasks (two such attempts were the Cogwatch project and the COACH project).
Where does this leave us?
Almost 41% of people after stroke in UK felt they did not receive the help they needed (McKevitt C et al., 2011). The evidence for efficacy of cognitive rehabilitation in post-stroke care is scarce, apart from aphasia treatment with SLT. Does this mean cognitive rehabilitation does not work in stroke at all? Are the studies to blame? Do people just improve on their own?
Some of the data that is generalised to stroke populations comes from the traumatic brain injury datasets (Chung et al., 2013), or is limited to people who have had a right-hemisphere stroke (Bowen et al., 2013). It is true that stroke research is particularly challenging, due to high variability of patients and ways in which stroke has affected them, difficulty of access to hospital groups and drop out rates. Finally, it is virtually impossible to fool people when it comes to cognitive rehabilitation (that is, to run a placebo trial).
There is an alarming necessity for good science in stroke cognitive rehabilitation (matching the level of attention and funding resources devoted to motor rehabilitation). That means studies based on randomised controlled trials with large sample sizes, well described and well designed measurement of functional outcomes (patient-centred and relevant for independence in daily life) and easily followed up. That way, results can be compared to each other. This calls for collaborative, multi-site research, with replicable designs and cross-validated methodology of testing. Good science across many labs. One such initiative is the RELEASE initiative for aphasia treatment.
Finally, let’s address the elephant in the room. There is substantial evidence from motor rehabilitation studies to suggest that the window for brain reorganisation post-stroke is very short and is probably closing somewhere between the first couple of weeks to 3 months after the event (Ward et al., 2017). Research supports rehabilitation starting as soon as possible within the first month after the accident, which currently does not take place as standard practice (Krakauer et al., 2012, Wahl et al., 2015). Perhaps the same interventions could have worked better if applied earlier.
Some of the studies included in Cochrane Reviews cited herein reached out to patients from days to months and years after stroke onset. As pointed out by Brady et al. 2016, in their Cochrane Review of aphasia rehabilitation (which included subjects up to 29 years post stroke) the timing of an intervention following stroke may be an important factor in therapy effectiveness and tolerance to specific paradigms. For example, the authors found that high intensity training was only more beneficial for patients who were already in a rehabilitation programme within 3 months post stroke. Sometimes, however, people find they do improve long after the presumed recovery window.
In the meantime, while we wait for more convincing science to direct us down the best path, we should put maximum effort into helping people to get better as soon as possible after stroke. For patients, it is worth putting up a fight to regain part of the old selves – both in terms of abilities and personality, even if some deficits persist (such as ability to write or read or speak fluently). For all of us, a happy life sometimes means compromises and adjustments. But those of us working in stroke research, or in clinical practice with stroke survivors, need to keep looking for answers to the question: how can we make this process easier for stroke patients and assist them in their journey?
Join in the conversation on Twitter with @CochraneUK #LifeAfterStroke or leave a comment on the blog.
Dr. Bienkiewicz has nothing to disclose.