Cognitive Rehabilitation after Stroke
Overview of the Project
The goal of our project was to develop adaptive, computer-based cognitive training for post-stroke rehabilitation. We focused on prospective memory (PM) as PM failure can interfere with independent living and result in, for example, forgetting to take medication, to switch off the stove or miss doctor’s appointments.
There is recent evidence in literature to show that using visual mnemonics might help improve skills used by prospective memory. Starting from those findings, we developed a comprehensive treatment based on visual imagery, and a Virtual Reality (VR) environment where stroke survivors can improve their prospective memory.
We evaluated our approach with three groups of people: healthy young people, healthy older people, and stroke survivors.
Having several studies provided us with a cross-dimensional view on how PM works in these age ranges and furthermore, if the treatment is a successful strategy for improving PM skills.
The first two studies were short, and focused on the effect of our visual imagery training only on the two groups of healthy participants. The third study involved a longer, more sophisticated visual imagery training, followed by practice in the VR environment.
The first study showed that young healthy people generally do not have problems with prospective memory. When asked to use visual mnemonics, high scorers in the treatment group seemed to do better and increase in recall items than their counterparts in the control group.
Low scorers however, either did not seem to benefit from using visual mnemonics or chose not to use visual mnemonics.
The second study demonstrated beneficial effects of our treatment on older healthy people, showing a significant increase in their ability to recall PM tasks after a short period of training.
In the study, the participants were taught how to use visual imagery by interacting with a computer-based tutorial (10 minutes) and later were evaluated on memorising and performing PM tasks by interacting with pre-recorded videos.
Even though the session was short (2 hours) there was a statistically significant difference in the participants’ ability to recall PM tasks. Using visual mnemonics and making the scenario personal and concrete in their minds significantly improves chances of recall.
The third study involved recruiting stroke survivors. Each participant attended ten sessions, over 10 weeks. We faced a lot of difficulties recruiting participants who met the inclusion/exclusion criteria, and we completed the study in October 2015.
We collected a lot of data.
The most important finding from the study showed that our intervention improved the PM skills significantly and the effect was stable (as measured four weeks after the end of treatment).
What is Prospective Memory?
When thinking about memory we often think about remembering past events: What did I do for my last birthday? What did I have for dinner yesterday? Where did I go for my last holiday?
Remembering things from the past is called retrospective memory. Retrospective memory only covers one aspect of memory. The other is called prospective memory.
Prospective memory is remembering future events. We use prospective memory very often in our daily lives: "I need to remember to go to my doctor next Tuesday" is an example of prospective memory. Anything that involves thinking about future events or planning requires prospective memory.
Prospective memory is essential to live independently and safely. Remembering the steps that we need to take before that deadline at work, or remembering to turn the stove off after a set amount of time requires prospective memory.
Interestingly, for prospective memory to work well, a person must also have relatively good retrospective memory. We must not only remember that we need to do something in the future but we also need to remember what we need to do.
The tasks that require prospective memory are often classified into two (or sometimes three) groups.
Time-based tasks are tasks that need to be done at a certain time. For example, my appointment with my client from work is tomorrow at 2pm. At 6pm, I want to watch the news on TV.
Event-based tasks are tasks that occur when a certain event happens. For example, after dinner I need to take my medication (dinner might occur approximately around a certain time, but the medication needs to be taken after the 'dinner' event).
When I go past the supermarket, I need to pop in and buy some milk. Sometimes, we also talk about another type of task - activity-based tasks. An activity-based task is very similar to an event-based task as the task occurs after an event. However, the events ae very closely related to one activity. However, we often view these as sub-tasks. Going out to play tennis might require a number of sub-tasks that trigger the next task. For example, putting on your tennis shoes might then prompt you to grab your tennis racquet. Each of the tasks required to get you to the tennis court might be classified as activity-based tasks.
People who have suffered from brain injury often also have problems associated with memory. Depending on the type and location of injury, a person might have reduced performance in both retrospective and prospective memory.
Prospective memory is often one of the main cognitive reasons for a loss of independence and even the need for long-term (and full-time) carers. A person's independence and safety often depend on the performance of prospective memory.
Often, this might lead to the person not being able to work. Sometimes, the person requires carers to ensure their safety is not compromised (e.g. the stove gets turned off after cooking, and the correct medication is taken at the right time).
Stroke is one of the leading causes of death and disability in our country. With our aging population (inverted pyramid) and the incidences of a stroke at younger ages, the need to provide cognitive support and rehabilitation is increasing.
The rehabilitation provided needs to be cost-effective and ideally (eventually) be customised to the individual's needs.
Customising it might mean having the training at the best times for the individual (this is particularly important for those who have suffered brain injury) or altering the levels of difficulty and providing additional support, etc.
