Featured Research

from universities, journals, and other organizations

No evidence of Alzheimer's disease-associated changes in adolescents carrying genetic risk factors

Date:
April 7, 2014
Source:
IOS Press BV
Summary:
Two studies indicate that some of the pathologic changes associated with Alzheimer's disease in older individuals are not apparent in young people who carry the apolipoprotein (APOE) genetic risk factor for developing the disease. In the first study, no differences were found in hippocampal volume or asymmetry between cognitively normal adolescent carriers and non-carriers of the ApoE ɛ4 or ɛ2 allelles. The second study reports no differences in plasma concentrations of amyloid-β peptides among young adult ɛ4, ɛ3 or ɛ2 carriers.

Two studies published in the Journal of Alzheimer's Disease indicate that some of the pathologic changes associated with Alzheimer's disease in older individuals are not apparent in young people who carry the apolipoprotein (APOE) genetic risk factor for developing the disease. In the first study, no differences were found in hippocampal volume or asymmetry between cognitively normal adolescent carriers and non-carriers of the ApoE ɛ4 or ɛ2 allelles. The second study reports no differences in plasma concentrations of amyloid-β peptides among young adult ɛ4, ɛ3 or ɛ2 carriers.

Carriers of the apolipoprotein (ApoE) ɛ4 allele are at greater risk for developing late-onset Alzheimer's disease (AD), develop AD at an earlier age, and experience a more severe cognitive decline and shorter survival times. The ɛ4 allele has also been linked to the severity of hippocampal atrophy and pathological alterations in the neocortex. The ɛ2 allele is thought to exert protection against the disease.

"Atrophy of the hippocampus, a region of the brain crucial for memory, is a common feature of AD, although it may also be detected in asymptomatic individuals as well as healthy adult carriers of the ApoE ɛ4 allele," explained Andy Simmons, PhD, of the Department of Neuroimaging of the Institute of Psychiatry of King's College London. "Whether young people genetically at risk for AD manifest early changes is an important question for those interested in interventions or treatments designed to slow or stop the progression of the disease."

To address the question, 1412 adolescents underwent MRI imaging and had blood samples tested for DNA analysis in order to determine their ApoE status. "Contrary to some recent studies, no hippocampal volume differences were observed between carriers and non-carriers of the ApoE ɛ4 allelle," said Dr. Simmons. The investigators also looked for other potential changes, such as hippocampal asymmetry or gene dose-dependent effects on volume, but could find no associations with genetic status.

In addition to structural changes in the brain, patients with AD typically show an increase in the brain load of amyloid-β (Aβ) peptides and a decrease in cerebrospinal fluid (CSF) concentration of Aβ peptides. Similar changes are found in almost all persons with mild cognitive impairment at risk of conversion to AD. "These changes represent the earliest diagnostic tools in AD," explains Professor Dr. med. Piotr Lewczuk, head of the Lab for Clinical Neurochemistry and Neurochemical Dementia Diagnostics, at the Department of Psychiatry and Psychotherapy, Universitätsklinikum Erlangen and Friedrich-Alexander-Universität Erlangen-Nürnberg. Since to some extent alterations of the concentrations of Aβ peptides are also observed in the blood, his research group explored differences in plasma levels of Aβ peptides among young adult ε4, ε3 or ε2 carriers.

To see whether these changes associated with AD are present at an early age, before clinical symptoms are apparent, investigators measured Aβ peptide concentrations in the plasma of 175 cognitively normal young adults. 40 individuals (22.9%) had at least one ε4 allele and were considered "at risk" for AD, 111 (63.4%) had the ε3/ε3 genotype and were considered "neutral," and 24 (13.7%) in the "protective: group had at least one ε2 allele.

The investigators measured four Aβ peptides and found that no significant differences in plasma levels of any of the Aβ peptides were found among the three genetic groups.

"The lack of differences of the Aβ concentrations reported in this study between the groups with and without increased genetic risk of AD does not mean that ongoing pre-clinical neurodegeneration can be fully excluded in all young subjects," says Dr. Lewczuk. He also notes that around 40% of AD patients are not carriers of the ε4 allele. However, he believes that both Dr. Simmons' findings concerning hippocampal volume and his study on plasma Aβ concentrations suggest that the AD-suggestive alterations begin perhaps 20-30 years before the onset of clinical symptoms, but most probably not earlier.


Story Source:

The above story is based on materials provided by IOS Press BV. Note: Materials may be edited for content and length.


Journal References:

  1. Andrew Simmons et al. No Differences in Hippocampal Volume between Carriers and Non-Carriers of the ApoE ε4 and ε2 Alleles in Young Healthy Adolescents. Journal of Alzheimer’s Disease, March 2014 DOI: 10.3233/JAD-131841
  2. Ruediger Zimmermann, Ellen Huber, Christine Schamber, Natalia Lelental, Barbara Mroczko, Sebastian Brandner, Juan Manuel Maler, Timo Oberstein, Maciej Szmitkowski, Manfred Rauh, Johannes Kornhuber and Piotr Lewczuk. Plasma Concentrations of the Amyloid-β Peptides in Young Volunteers: The Influence of the APOE Genotype. Journal of Alzheimer’s Disease, May 2014 DOI: 10.3233/JAD-132687

Cite This Page:

IOS Press BV. "No evidence of Alzheimer's disease-associated changes in adolescents carrying genetic risk factors." ScienceDaily. ScienceDaily, 7 April 2014. <www.sciencedaily.com/releases/2014/04/140407090359.htm>.
IOS Press BV. (2014, April 7). No evidence of Alzheimer's disease-associated changes in adolescents carrying genetic risk factors. ScienceDaily. Retrieved July 23, 2014 from www.sciencedaily.com/releases/2014/04/140407090359.htm
IOS Press BV. "No evidence of Alzheimer's disease-associated changes in adolescents carrying genetic risk factors." ScienceDaily. www.sciencedaily.com/releases/2014/04/140407090359.htm (accessed July 23, 2014).

Share This




More Mind & Brain News

Wednesday, July 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Why Do People Believe We Only Use 10 Percent Of Our Brains?

Why Do People Believe We Only Use 10 Percent Of Our Brains?

Newsy (July 22, 2014) — The new sci-fi thriller "Lucy" is making people question whether we really use all our brainpower. But, as scientists have insisted for years, we do. Video provided by Newsy
Powered by NewsLook.com
Do Obese Women Have 'Food Learning Impairment'?

Do Obese Women Have 'Food Learning Impairment'?

Newsy (July 18, 2014) — Yale researchers tested 135 men and women, and it was only obese women who were deemed to have "impaired associative learning." Video provided by Newsy
Powered by NewsLook.com
Does Mixing Alcohol and Energy Drinks Boost Urge To Drink?

Does Mixing Alcohol and Energy Drinks Boost Urge To Drink?

Newsy (July 18, 2014) — A new study suggests that mixing alcohol with energy drinks makes you want to keep the party going. Video provided by Newsy
Powered by NewsLook.com
Pot Cooking Class Teaches Responsible Eating

Pot Cooking Class Teaches Responsible Eating

AP (July 18, 2014) — Following the nationwide trend of eased restrictions on marijuana use, pot edibles are growing in popularity. One Boston-area cooking class is teaching people how to eat pot responsibly. (July 18) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins