Neuropsychological testing

As a neuropsychologist, I’m someone who has a particular interest in seeing how any type of brain damage or brain disease can affect our behaviour. And particularly, our ability to think, to remember, to communicate, and to perceive. And so for different forms of dementia, we try to use tests– sometimes spoken tests, sometimes paper and pencil, sometimes on a computer– to ask people questions or give people tasks to do which tap into those particular skills. So for example, with someone with Posterior Cortical Atrophy two of the early tests I’d like to run in order to support that notion is to test are there aspects of their perception which are not what I would expect for someone of that age and background?

So for example, if I show them the outlines of objects. So it’s a can you see what it is task. But it’s made harder by the fact I don’t give them all the internal detail. Can they perceive what those are? Or can they do things like counting out dots? Can they perceive where the dots are and count the right number? Are there too many or too few? And I want to contrast that with what I think should be the case for someone with PCA is that their episodic memory, their ability to lay down new information and then retrieve it is relatively preserved for someone of their age. So I might give them something like a word retrieval task.

Where I give them a series of words. And then I say, did I just say to you x or y. And see if they can recognise that one of those words is more familiar because I’ve just said it out loud. But of course, you have to be careful to tailor the tests for each person to make sure that you’re not tripping them up for another reason. So for example, there are lots of memory tests which are visual in nature. Like I show you a bunch of faces and then say, which of these people have you seen before?

That’s a hopeless task, obviously, for someone with PCA because it’s not measuring their memory, it’s measuring their ability to perceive the face in the first place. And so you have to have a sense of the whole cognitive profile, the whole way in which the disease you suspect may be operating has affected all of these different skills. So that the choice of tasks you have is optimised for them. The reason we do these sorts of thinking tasks is because we know different parts of the brain are specialised for different skills.

But also that someone of a particular age and educational background and social background, for example, there are certain bits of information which we all are likely to have acquired during our life. Which might be general things, like the meaning of words, or more fluid capacities, like the ability to solve problems. For example, to see that two things are similar or that one something is the odd one out and doesn’t fit within a group. And so what we’re trying to do is to observe people’s abilities, both what level they’re at as in are they so-called normal or average for someone of that background? And also is their profile even?

So are there distinct areas where they’re much, much better at one thing than another. Indicating that perhaps one or more skills has been impaired. And because we know which parts of the brain are specialised for different skills, we can make interpretations, or guesses, as to which parts of their brain– the front, the sides, the back– might be compromised in some way, either by physical damage, by a progressive process. We, of course, have to be aware that there are lots of things which can affect our cognition. So even everyday things like having a cold or the flu will slow down your thinking speed and make you more sluggish. We know that education, of course, has a huge impact.

And also, one’s mental health. People who are anxious, for example, often report memory difficulties because they’re so distracted from what they’re trying to remember from the conversation they’re in, or they’re not very present in that moment, that they find it, then, difficult to recall afterwards. And so we have to try and tease out these things. And it’s particularly, when someone first presents to their doctor saying, I’m worried about my memory, or my language, or whatever, that it’s often most difficult to discriminate the exact nature of this difficulty and whether this is something which is abnormal, which is accountable for by something else in their life, and also whether it’s changing.

So in a dementia clinic, you are asking the question, not what they’ve got, but are they losing it? Is there change over time?