Cognition in ALS and the overlap with frontotemporal dementia (FTD)

Published on June 30, 2016   44 min
0:00
My name is Dr. Thomas Bak and I work at the University of Edinburgh. I would like to speak about cognition in ALS and in particular about the overlap with frontotemporal dementia. Now you might start asking what is cognition in ALS, isn't it referred to as motor neuron disease which per definition should be motor. I hope that by the end of this lecture, I would have convinced you not only that cognition is a very important part for the clinical in vitro of ALS, but that it is an absolutely integral part for our understanding of the disease.
0:37
So to start with the structure of the talk, I will first speak about the history of our discovery of cognitive symptoms in ALS, addressing the question whether this is really a recent discovery or something which in fact can go back much more in time. I will then move to discuss the nature of cognitive deficits, in particular the frontal-executive dysfunction, social cognition behavior, and language. And then I would come to what I think is a central question, why is cognition affected in ALS, and finally, after hopefully convincing you that it's an important part of the disease, I want to speak a little bit about assessment of cognitive symptoms, how can we assess them, how can we really judge whether they're present or not.
1:23
So you might be surprised that the first slide I start with here is from 1893, quite long time ago and incidentally from Japan. This was until recently and arguably little known piece of work published in Journal of the Medical Society of Okayama, which would not be famous even in Japan, but I think this is very interesting. It happens to be the first description of aphasia, namely language disorder associated with brain disease in Japan. But what makes it really interesting is that this first description of aphasia was in context of motor neuron disease. So already in 19th century, physicians have noticed that at least some of the patients with ALS might have something wrong with their cognitive functions. In this case interestingly, there's a description of a disorder of speaking but also of writing and reading, affecting one part of Japanese writing, kana more than kanji, I will come to it much later where I just hope it will become relevant.
2:31
Now the next slide is showing just a brief selection of 12 papers, all of them written before 1935, which write quite a lot about cognitive and behavioral symptoms in ALS. And the one I'd like to stress most is from Braunmuhl 1932. To the best of my knowledge, this is the first paper which not only described cognitive and behavioral problem in ALS patients, but which explicitly made the link between ALS and frontotemporal dementia. At that time, of course, von Braunmuhl referred to it as Pick's disease, but that would have been then term for frontotemporal dementia. So that means the recognition that there might a particular connection between FTD and ALS goes back at least to 1932. Von Braunmuhl is quite explicit it's not Alzheimer's disease picture, it was well known by then already, it is FTD.
3:32
Now there are other remarkable features of those early descriptions of cognitive and behavioral symptoms in ALS. So on one hand we have single case reports of patients with overt dementia, so patients would really were diagnosed with a dementing illness. On the other hand, you have also subtle cognitive changes in non-demented patients, so it was recognized that there is a lot of variety that some patients might be very much impaired enough to be diagnosis with dementia but others might show similar but much milder symptoms.
4:10
Another interesting thing is that it was recognized that those problems might be fairly common and in fact in one of the studies half of 18 pathologically confirmed cases were described as psychologically feeble, and this is a study from Raymond and Cestan from 1905, and Van Bogaert, 1925, described psychic alterations in 13 out of 31 patients. Now please remember we speak between 30% and 50%. I will come to it in a few slides, the number will become relevant.
4:45
Another thing which is remarkable is that the clinical features are very much not what you would describe in a very, very recent labor, in fact, I have just written a chapter on dementia and cognitive changes and we have similar features. So that time course that was described was of dementia usually starting with dementia's cognitive symptoms, followed by the classical ALS. Very often there were prominent bulbar features, dysarthria and dysphasia. And the rate of deterioration in those patients was faster than in ALS patients without dementia. Many of those studies for pathology and when the pathology was available, it showed in fact very typical ALS pathology including for instance changes in the hypoglossal nucleus but also frontal and frontotemporal cortical atrophy and neuronal loss.
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Cognition in ALS and the overlap with frontotemporal dementia (FTD)

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