Humans normally have 23 pairs of chromosomes in their cell nuclei; one copy (in each pair) from their mother and the other copy from their father. Down’s syndrome is caused by the presence of an extra copy of chromosome 21, and people with this condition are at a greatly increased risk of developing epilepsy. In adulthood the onset of seizures in this population is very often linked to Alzheimer’s disease. In fact it is reported that as many as 50-80% of people with both Down’s syndrome and Alzheimer’s disease have epilepsy, and that the more severe their seizures are the more rapid their cognitive decline is likely to be.
Despite the significant impact of seizures in people with Down’s syndrome and Alzheimer’s disease, the mechanisms underlying them are poorly understood. Dr Frances Wiseman and colleagues, at University College London, have been awarded £29,897 over eight months, for a pilot grant entitled A mouse model of seizures in Down’s syndrome/Alzheimer’s disease, in which they will create an experimental model with which to study these pathways more closely.
The team has already developed a mouse model of Down’s syndrome, and they are using it to find out more about the condition. In the current study, they plan to create a model of Down’s syndrome-Alzheimer’s disease co-existence by breeding Down’s syndrome mice with mice that have a mutant gene associated with Alzheimer’s disease. They will then investigate whether the new model is more susceptible to seizures than the Alzheimer’s disease model – as is the case in humans.
If seizure susceptibility is found to be increased in the new model, it could potentially become an effective tool with which to explore the impact of epilepsy in co-existing Alzheimer’s disease and Down’s syndrome. In the future it could be help to identify new treatment targets and, in the longer term, develop and test novel therapies for this devastating condition.