Young people do not display symptoms despite genetic predisposition
A loss of memory capacity is the first symptom of Alzheimer’s disease and usually becomes apparent in sufferers between the ages of 65 and 75. At this point in time, most patients have probably already been suffering from Alzheimer’s disease for around ten to twenty years. However, when exactly the onset of the disease occurs is still unclear. Researchers lead by Prof. Dr. Piotr Lewczuk at the Department of Psychiatry and Psychotherapy (head of department: Prof. Dr. Johannes Kornhuber), FAU, have recently gained new insight in this area. They have discovered that young people – around 30 to 40 years before the typical onset of the disease – do not show any signs of Alzheimer’s disease despite genetic predisposition.
During its early stages, Alzheimer’s disease can only be verified by examining the cerebrospinal fluid. Medical experts inspect the fluid for changes in the concentration of a peptide called amyloid β which accumulates in the brains of patients with Alzheimer’s disease. A low level of amyloid β in the cerebrospinal fluid is considered the earliest indication of Alzheimer’s disease. Patients with suspected Alzheimer’s disease are regularly tested for low amyloid β levels at facilities such as in the laboratory in Erlangen lead by Prof. Lewczuk.
The Erlangen-based researchers wanted to find out whether this initial indicator of Alzheimer’s disease could be found in young adults. They examined blood samples from volunteers aged between 20 and 35. Some of the participants were carriers of a genetic risk factor for Alzheimer’s disease – the apolipoprotein e4 allele – but did not have any memory problems. The results of the investigation showed that their blood samples did not display any differences when compared with test subjects who did not have the same genetic predisposition.
While the FAU researchers’ findings may seem unspectacular at first glance, they help medical experts to better understand the progression of Alzheimer’s disease. ‘The results lead us to conclude that even people who carry genetic risk factors do not yet have the disease at earlier stages in life. It is very likely that the onset of the disease occurs around ten to twenty years before the first symptoms become evident – this is the conclusion drawn from earlier studies carried out in Sweden,’ explains the head of the study Prof. Dr. Piotr Lewczuk.
The apolipoprotein e4 allele is considered a risk factor for Alzheimer’s disease. However, not all carriers of this genetic characteristic actually develop Alzheimer’s disease during their lifetimes. Furthermore, people who are not genetically predisposed can still develop the disease. Diabetes, high blood pressure and advanced age are the main factors which contribute to the disease.
Important findings with regard to when and how the disease develops could be provided by a follow-up study by the FAU researchers. ‘We would like to investigate whether the concentrations of amyloid β peptides in the people who have already been studied remain stable until any initial changes in memory capacity become apparent,’ says Lewczuk. ‘However, the fundamental ethical and logistical issues need to be clarified first before we can start work on this long-term project.’
The researchers recently published the results of their study in the prestigious ‘Journal of Alzheimer’s Disease’.
Zimmermann R., Huber E., Schamber C., Lelental N., Mroczko B., Brandner S., Maler J.M., Oberstein T., Szmitkowski M., Rauh M., Kornhuber J., Lewczuk P. J., Alzheimer’s Dis. 2014 Feb 20.
Prof. Dr. Piotr Lewczuk
Phone: +49 9131 8534324