A strong link between the onset of Alzheimer’s and epileptic seizures
In adults with Down syndrome, the risk of developing Alzheimer’s disease is particularly high due to genetic factors. In this study, we focused on analyzing the natural history of epilepsy in this population, observing how the appearance of the first symptoms of Alzheimer’s disease marks a decisive turning point in the development of epileptic seizures.
What was done in this study?
In our research team, we conducted a multicenter observational and longitudinal study analyzing data from seven international cohorts. The study followed adult participants with Down syndrome (with a mean age of 43 years) over a overall observation period ranging between October 24, 2012, and July 28, 2025. We evaluated the onset of epileptic seizures—especially myoclonic and tonic-clonic—and their relationship with the symptomatic onset and progression of Alzheimer’s disease.
The study was led by researchers from our team at the Sant Pau Memory Unit (Dr. Lucía Maure-Blesa and Dr. María Carmona-Iragui) and was carried out in collaboration with seven international cohorts.
Main results
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Progressive increase in seizures: The cumulative incidence of epilepsy increases from 9.5% at the time of Alzheimer’s diagnosis to 56.9% after nine years.
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Most frequent types of seizures: The most common seizures following Alzheimer’s onset are myoclonic (brief muscle jerks) and tonic-clonic (loss of consciousness with stiffness and convulsions).
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Associated risk factors: The risk of epilepsy increases linearly following the clinical manifestation of Alzheimer’s. Furthermore, it is higher in individuals with severe or profound intellectual disability and in carriers of the APOE 4 allele.
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Impact on prognosis: The presence of late-onset myoclonic epilepsy is associated with faster cognitive decline and a 2.10-fold higher risk of mortality.
Why is it relevant?
These findings demonstrate that the onset of epileptic seizures is strongly linked to the clinical debut of Alzheimer’s disease in adults with Down syndrome. The clinical relevance is immediate: healthcare professionals and families must maintain a high level of suspicion and vigilance regarding potential epileptic seizures from the early stages of Alzheimer’s, as some manifestations (such as small morning spasms) can easily go unnoticed. Furthermore, it opens the door to investigating whether seizures exacerbate the neurodegenerative process or serve as a direct marker of a more aggressive disease variant.