New research reveals that the gene variant strongly associated with an increased chance of getting Alzheimer’s disease later in life could affect cognitive health in childhood. The study conducted by a collaborative team of scientists from UC Riverside and the University of Colorado, Boulder found that those carrying the gene scored slightly lower on IQ tests in childhood, thus implying that cognitive decline is apparent at a younger age than ever previously realized.
The gene variant is called APOE4 and it is thought to be present in around 15% of the population. If a person carries one copy of an APOE4 gene they are three times more likely to develop Alzheimer’s compared to those without the gene. Exactly why this is so is still uncertain and has therefore been the source of much research these days.
The prevailing view among researchers now is that the gene codes for a protein that somehow heightens the ability for other toxic proteins to accumulate in the brain. This accumulation of toxic proteins is what ultimately results in the neurodegeneration associated with Alzheimer’s.
There came to be a recent hypothesis that the APOE4 gene variant may be associated with structural brain differences that can be detected in early infancy. If this were true, that person would have a lower cognitive performance in childhood. Then, further on in life, it would continue to lower the person’s cognitive reserve, which is something known to mitigate the impact of Alzheimer’s pathology in one’s senior years.
To investigate this hypothesis, the Colorado scientists compared IQ test scores from children with different APOE genotypes. Data from over 1,300 subjects between the ages of six and 18 was analyzed.
Overall, they found the IQ scores to be two points lower for every copy of the APOE4 gene a person carried with the effects being more prominent in females than males. The higher prominence in females links to the fact that women suffer from Alzheimer’s at higher rates than men.
These results suggest that that the effects of the APOE4 gene variant on cognition may come into play at a much earlier age, and so have an influence on fundamental brain structure and general intelligence – which ultimately adds to a person’s susceptibility to cognitive decline later in life. In other words, the gene doesn’t only play a role in the progression of cognitive decline in adulthood, it also affects the brain during development in childhood. The study was published in the journal Neurobiology of Aging.
Chandra Reynolds, corresponding author on the new study, concluded:
Our results suggest that cognitive differences associated with APOE may emerge early and become magnified later in the life course, and if so, childhood represents a key period of intervention to invest in and boost reserves.
Next, the researchers plan to expand the scope of the study, looking at IQ and cognitive ability data from subjects spanning 28 to 46 years of age. The data collected from this next phase of their study will bridge the gap between the research from younger years and older years. Ultimately, their aim is to understand whether cognitive development in younger years can be enhanced to grow a person’s cognitive reserve and help protect from more dramatic declines in old age.
The study also hopes to lead to the development of the earliest biomarker for later vulnerability to Alzheimer’s disease. It could also lead to gene therapies to decrease the risk of Alzheimer’s and possibly increase cognitive ability throughout life.
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