'The onset of dementia is delayed by four to nine years in people who speak more than one language'

–What is it about the brain that has made you dedicate so much of your life to it?

–We humans are our brains. They regulate everything and I have been specialised in that field since 1980, when I started to work with people who had lost their language through some type of brain damage. My interest was always in studying the biological bases of language. It is what makes us humans, what differentiates us from other primates and it is a fascinating and enigmatic subject, although society hardly pays it any attention.

–How can we care for our brain better?

–A stroke is one of the most common causes of aphasia, so we have to control the vascular risk factors (hypertension, diabetes, cholesterol, smoking, obesity, a sedentary lifestyle etc), but there are also other things that a healthy person can do. For example, someone who is bilingual has greater cognitive reserve, more ability in their brain than someone monolingual. In fact, the symptoms of dementia are delayed by between four and nine years in people who speak more than one language, so using another language, reading it and understanding what you are reading is fundamental. The part of the brain that regulates our language has to be kept active, so speaking one or several others is desirable.

–After so many years of study, what has been most revealing?

–Historically, it was believed there was only a remote possibility of recovering language after a total or partial loss as a consequence of brain damage; now, we know that is not so. That has been the major challenge: finding ways for people with aphasia to communicate again in some way and recover their quality of life.

–The announcement that Bruce Willis was retiring after being diagnosed with aphasia has focused the media spotlight on this disorder. What is the probability of a healthy person suffering from it?

–Aphasia has multiple causes: in adults, the most common is a stroke and cardiovascular accidents in general; also neurodegenerative illnesses such as Alzheimer's or primary progressive aphasia, which is probably what Bruce Willis has; but also, it could be tumours or head trauma. The older you are, the higher the risk of suffering from one of these conditions, and therefore the probability of aphasia. It is a symptom of certain neurological conditions and its clinical characteristics and the way they evolve in the long term are different. With a malignant tumour it is going to be worse than in someone who has a stroke. In general, the illnesses that affect the left hemisphere of the brain, which is responsible for language, are susceptible to causing aphasia. The vast majority of right-handed people have lateralised language in the left side of the brain. Those who are left-handed tend to behave similarly to right-handed people, but may have more atypical localisations in both brain hemispheres and, exceptionally, in the right hemisphere. That also occurs with those who are ambidextrous.

–Does that mean the risk of suffering aphasia is related to whether a person is right-handed or left-handed?

–Not necessarily, because we see right-handed people who recover well and left-handed or ambidextrous people who don't. Aphasia is a heterogeneous disorder in which many personal characteristics are involved. If someone who is illiterate is affected by it, it won't be the same as a person with high ability. Their capacity for recovery is very different. An illiterate person has a very limited vocabulary, surprisingly it consists of only 300 to 500 words, while a university graduate can use around 30,000 words. That means their language is wider, richer and more distributed in the brain. The margin for recovery is greater in someone who has more vocabulary, because they have more resources, more possibilities of finding alternatives for those words that they cannot pronounce.

–Can aphasia happen from one day to the next?

–It depends. Bruce Willis had time to prepare press releases announcing his retirement so that makes us think his illness evolved slowly, like neurodegenerative illnesses do. On the other hand if someone has a stroke, they go from being able to speak to not being able to, just like that. It is a sudden change and that indicates what the cause might be.

–And when it happens, how do people manage the helplessness of wanting to express themselves verbally but not being able to?

–It depends on the severity of the aphasia. About 30 per cent of secondary aphasias are serious, although that does not necessarily mean they are not going to improve. However, aphasia is a devastating disorder. In a study carried out in Toronto, Canada, in 2010, they asked 65,000 elderly people in care homes what most affected their quality of life. Aphasia was number one, ahead of cancer and tetraplegia. When someone loses the ability to speak they are going to lose their job, their finances will be affected, their relationships with family and friends are going to be different, they are at greater risk of suffering depression, anxiety and frustration. They will lose autonomy, because sometimes they can't move. Aphasia is the cornerstone, but there are a number of knock-on effects that reduce quality of life. That's why our job is not just to deal with the language problems, but all the associated side-effects.

–What is the darkest side of this disorder?

–The worst case is when there are a lot of side effects. There are many serious and even fatal illnesses which for a long time do not create the same impediments. For example, a patient diagnosed with amyotrophic lateral sclerosis, which is also devastating, can live acceptably for the early years. However, someone with aphasia loses so much from the first day. The only difference from the rest is that they may recover, at least partially.

–Are there unmistakeable signs that something is not right?

–Yes. The first is someone's ability to communicate as they usually do, difficulty in remembering certain words or slow communication. They also start to say words that don't make sense, may not understand what they read, or be able to read aloud, or write. Those all indicate an alteration in language and are a warning sign, especially if they happen suddenly. In neurodegenerative illnesses, the most common symptom is an inability to pronounce words, for example if they want to say 'cup' but can't. They know what they want to say, but can't access the word to speak it.

–And do the authorities provide suitable treatment?

–Stroke units play an essential role in early diagnosis in order to reverse the effects so aphasia does not occur or, if it does, it is less severe. When it comes to chronic care, I think it could be improved. As society doesn't know what aphasia is, the State doesn't pay much attention to it. The resources are good, but could be optimised. Remote care is one of the most-used methods during the pandemic and it is more economical than in-person therapies. I hope it will continue. In fact, we have a project which aims to show that online therapy can work and is cheaper to apply. It reduces the costs and doesn't leave the patients isolated, because one of the reasons aphasia patients give up on their therapies is the problem of transport.

–What role does your unit play?

–It was created in 2004 and since then the team, which is multidisciplinary, has increased in terms of researchers. There are psychologists, speech therapists, linguists, computer engineers (neuro-imaging) and neurologists to treat all aspects of the disorder. We have been pioneers in the treatment of aphasia with medication and we use it together with intensive rehabilitation and non-invasive brain stimulation techniques. Used together, the results are more robust.

–But at the moment your unit still only carries out research.

–It is a research unit with ongoing projects in which people who meet a number of criteria are welcome to participate. But not everyone with aphasia, because we are not a treatment centre. We would be overwhelmed if we tried to do both: in Andalucía alone, 7,000 people a year suffer a stroke. However, as a public institution, we do give free advice and analysis.

–What comes next?

-We now know a great deal about the left hemisphere and how the brain repairs itself, but one of the greatest challenges is identifying predictive factors. We would like to know whether someone is going to be able to recover fully or not, so that we can adapt our treatment strategy with that knowledge to hand and find what will work best for them.