Tag Archives: Alzheimer’s disease

Infants, Down syndrome and the Alzheimer disease: A multidisciplinary approach

This post was contributed by Aline Lorandi, a visiting postdoctoral researcher under the supervision of Prof Annette Karmiloff-Smith, investigating the precursors of phonological awareness in Down Syndrome. She also is a collaborator in the infant stream of the London Down Syndrome Consortium (LonDownS), which investigates the links between Down syndrome and the Alzheimer disease

One of the premises of developmental neuroscience is based on the fact that, in order to understand certain phenotypes, it is crucial that we investigate their origins, that is, that we track the developmental trajectory that leads us to different sorts of behaviour, cognitive profiles, disorders, and diseases.

DNA StrandsWe must also acknowledge that the advances made by the field of developmental neuroscience allow us to take the debate between the contribution of genes and environment to another level: It is a fact that it is only possible to understand such contribution in a bilateral way, in which one modifies the other all the time.

With all that in mind, we can understand the curious title that Dr Esha Massand gave to her talk: ‘What can infants possibly tell us about Dementia?’ It seems a bit odd to think how studying babies can provide us any kind of relevant information about a condition typically related to ageing. Nevertheless, from the study of Down Syndrome arose the inspiration to establish the link between child development and Alzheimer’s disease.

The research described by Dr Massand is part of the LonDowS Research Consortium, involving different universities, which works in five sites: Genetics, mouse models, cells, adults, and infants.

The aim of the infant stream, according to Dr Massand, is to understand individual differences in infancy that may point to early signs of Alzheimer’s Disease. It is known that individuals with Down Syndrome have an extra copy of chromosome 21, and there is a gene in this chromosome, called APP gene, that produces a protein that, because of this extra chromosome, will be overexpressed in all individuals from the womb throughout development.

This APP gene produces plaques that are found in the brains of individuals with Alzheimer’s Disease. As the APP gene is overexpressed in Down Syndrome, it is very important to investigate its relationship with Alzheimer disease. One of the interesting facts is that, although all individuals with Down Syndrome will present, by the age of 30 onwards, the plaques in their brains, not all of them will develop signs of Alzheimer’s Disease.

Using a varied range of methodologies (eye tracking, sleep pattern measuring, EEG/ERP, behavioural tasks), Dr Massand and colleagues aim to understand how behaviour and neural responses may shed some light on whether it is possible to track some early biomarkers that can point to the onset of the disease in a developmental way. Among the cognitive and neural underpinnings, they are looking at several abilities, such as memory, attention, language, sleep fragmentation, mother/father/infant interactions, and many others. All those methodologies are very child-friendly.

Although preliminary, many interesting results already point to important individual differences, like the relationship between language and the gap-overlap/disengaging effect (the ability to disengage from one stimulus to look at another one, concomitantly or not).

Dr Massand’s team found that the fewer words a child understands and produces, the longer he or she takes to disengage from the stimulus presented in the task. Additionally, the disengaging effect was positively correlated to aggressive behaviour. That means that the higher the score that the child reached in the behaviour questionnaire (related, among other measures, to aggressive behaviour), the longer he or she took to disengage from the stimuli.

They also found a positive correlation between the ability to pay attention to novelties and detect them, to more sleep. Analysing several trials during a test to find the location of the objects, they also discovered that children with Down Syndrome may take longer to habituate to the objects and may take longer in the tasks: While typically developing children can detect a change of location of the objects in a first trial, observable by the duration of them looking at the screen in the eye tracking, children with Down syndrome do better – or more ‘typically’ – in a second trial, presenting more variability in the first trial than typically developing children. All these findings are related to individual differences that may be correlated to those who will be at risk of developing Alzheimer disease.

Exciting trends and lots more to do for Dr Esha Massand’s team! There are more data to collect, especially from controls, findings from EEG/ERP to analyse, which may point to underlying neural differences related to Alzheimer’s Disease, and the exciting combination with the data from the other streams (cells, mouse models, genetics, and adults) to explore.

As the questions from the audience show, this is the kind of research that makes us excited and curious about! Should the participants be followed longitudinally? How long do children take to get familiarised to the cap in the EEG tests? These and other questions about the relationships between the different cognitive abilities were answered by Dr. Massand, who also highlighted that the hope is to find those individual differences in adults as well, in order to seek a better understanding of the factors that might indicate early clinical signs of the Alzheimer’s Disease.

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