A thinner entorhinal cortex, a structure in the lower middle part of the brain’s outer mantle, may render these youth more susceptible to degenerative changes and mental decline later in life, propose Drs. Philip Shaw, Judith Rapoport, Jay Giedd, and NIMH and McGill University colleagues. They report on how variation in the gene for apoliproprotein (ApoE), which plays a critical role in repair of brain cells, affects development of this learning and memory hub in the June, 2007 Lancet Neurology.
Previous studies had also implicated in Alzheimer’s one of three versions of a gene that produces ApoE. The ApoE4 variant occurs in 10-25 percent of the general population, but in 40 percent of late-onset Alzheimer’s patients. The strongest genetic risk factor for the disease discovered to date, ApoE4 has been linked to altered brain activity in adults and impaired neuronal development.
Shaw and colleagues suspected that youth with ApoE4 would have a thinner entorhinal cortex. To confirm this, they compared the MRI (magnetic resonance imaging) scans of 239 healthy children and teens with their ApoE gene types. Many were re-scanned as they grew up to see if there was any ongoing thinning process traceable to ApoE4.
Each individual inherits two copies of the ApoE gene, one from each parent. Youth with at least one copy of the relatively rare ApoE2 variant – which may confer a protective effect against developing Alzheimer’s – showed the thickest entorhinal cortex. This was the first evidence that the ApoE2 version, which is carried by 5-10 percent of the population, affects brain structure, say the researchers. Youth with two copies of ApoE3, the most common version (65-85% prevalence), had intermediate cortex thickness. Those with one or two copies of ApoE4 had the thinnest entorhinal cortex.
ApoE4 gene type also predicted thinning of two other brain regions (medial temporal and posterior orbitofrontal areas) affected early in Alzheimer’s disease, which, like the entorhinal cortex, are involved in learning and memory. The pattern of changes resembled that seen in early Alzheimer’s, but to a far lesser degree. For example, the entorhinal cortex thinning seen in Alzheimer’s disease is about 10-fold greater than in the youth with ApoE4.
Although they did not test for possible learning and memory deficits, the researchers found no difference in IQ attributable to ApoE gene type. Nor did the E4 variant accelerate loss of cortex tissue. The differences were fixed, and didn't progress. In fact, the researchers noted evidence that ApoE4 may even promote survival in infancy and protect the brain’s thinking capacity against damage from infectious illness.
"In the future we hope to determine whether this thinner cortex is associated with differences in brain activity during tasks of learning and memory in children," said Shaw.
Jules Asher | EurekAlert!
Single-stranded DNA and RNA origami go live
15.12.2017 | Wyss Institute for Biologically Inspired Engineering at Harvard
New antbird species discovered in Peru by LSU ornithologists
15.12.2017 | Louisiana State University
DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.
Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...
MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.
Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...
Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...
Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.
To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
11.12.2017 | Event News
08.12.2017 | Event News
07.12.2017 | Event News
15.12.2017 | Power and Electrical Engineering
15.12.2017 | Materials Sciences
15.12.2017 | Life Sciences