Genetic Risk Factors For Alzheimer's May Be Detected As Early As Age 18

A new research showed that scoring genetic risks may identify those at higher risk of developing Alzheimer's disease before symptoms appear, quite possibly even in healthy young adults.

Elizabeth C. Mormino, Ph.D., of Massachusetts General Hospital in Charlestown, and her colleagues unravel how they used the genetic scoring of Alzheimer's disease (AD) in healthy adults as young as 18.

According to CNN, there are already tests to determine a genetic risk for those whose family members suffer from Alzheimer's disease. Familial Alzheimer's disease usually develops earlier and is also less common compared to sporadic Alzheimer's disease, both type cause dementia. But, when it comes to determining those at risk for sporadic Alzheimer's, which accounts for about 95 percent of all Alzheimer's cases, scientists say that it's not as simple as it sounds.

Alzheimer's disease is known to be one of the most devastating and difficult diseases at present. It is said to affect more than 5 million adults in the United States, and the number is expected to rise three times in the next 30 years.

The authors of the study observed that the pathophysiologic processes of AD can possibly happen at least a decade before symptoms of the condition will start to show.

"Given that current clinical trials are testing whether therapies can slow memory and thinking decline among people at risk for the disease, it is critical to understand the influence of risk factors before symptoms are present," says Mormino.

For the study, Medical Xpress reported that researchers calculated a polygenic risk score or a numeric score based on the probability of a person having several high-risk gene variants, in 166 people with dementia and 1,026 people without dementia with an average age of 75.

Scientists searched for markers unique to Alzheimer's disease which includes memory and thinking decline, clinical progression of the disease, and the volume of the hippocampus which is the memory center of the brain.

Researchers also examined the connection between the risk score and hippocampus volume in 1,322 healthy, younger participants between the ages of 18 and 35.

Findings show that those older adults without dementia had a higher polygenic risk score which indicated worse memory and a smaller hippocampus at the study's baseline. Medical News Today explained that the risk score accounted for 2.3 percent of the variance in memory, and 2 percent of the variance of the hippocampus volume. The team also found that the polygenic risk score could be directly connected to an overall clinical progression of AD.

With the younger study participants, the researchers revealed that they found that higher polygenic risk score could be related to smaller hippocampal volume; the risk score accounted for around 0.2 percent of hippocampal volume variance.

The team said this indicates that genetic risk for AD is not specific to processes that occur in later life. They believe that these processes usually start in early adulthood.

"Overall, these analyses provide evidence that aggregate genetic risk of AD dementia exerts effects that are detectable before the clinical symptoms of dementia are present, even among young adults," researchers explained.

Authors also clarified that since their study only included a small number of participants, additional studies are needed. However, they still think their results could result to a better identification of people who are at a higher risk for developing AD and other dementias before they show the symptoms.

"The goal of this type of research is to help physicians better identify those at high risk of dementia so that future preventive treatments may be used as early as possible," Mormino said.