Subtle Brain Wave Activity Could Predict Alzheimer's Disease More Than Two Years Before Diagnosis

A slight alteration in brain wave activity may forecast Alzheimer's disease more than two years before a diagnosis, a new study suggests.

The signal may offer a sensitive biomarker for cognitive decline.

MEG study of mild cognitive impairment

Neuroscientists from Brown University in the US, Spain's Complutense University of Madrid and the University of La Laguna used a non-invasive imaging method known as magnetoencephalography (MEG) to examine resting brain wave activity in 85 people diagnosed with mild cognitive impairment.

The researchers identified clear differences in the brain wave patterns of participants who later developed Alzheimer's disease. Compared with people who did not progress to Alzheimer's over the same timeframe, this group generated beta waves less frequently, with lower power and for shorter periods.

"We've detected a pattern in electrical signals of brain activity that predicts which patients are most likely to develop the disease within two and a half years," says co-lead author and neuroscientist Stephanie Jones from Brown.

"Being able to noninvasively observe a new early marker of Alzheimer's disease progression in the brain for the first time is a very exciting step."

Beta waves and Alzheimer's disease progression

These patterns match a key change in beta-wave activity that usually happens at about age 60 in healthy people. After that point, such bursts of activity generally diminish, although the decline appears to progress more rapidly in people with Alzheimer's.

Recent MEG imaging research has associated minute changes in brain waves with learning, memory and executive function, backing the technique's use "as a biomarker of cognitive impairment."

Much depends on how MEG readings are, well, interpreted. They are commonly assessed as averages, but the scientists behind the new research argue that this approach can overlook vital detail. Instead, they applied a more closely focused analytical method.

Inhibitory cognitive control

Beta-wave bursts were eventually shorter among participants who later developed Alzheimer's. Some evidence indicates that beta-wave bursts across the brain are a marker of inhibitory control.

The researchers therefore believe that the capacity to adjust beta-wave bursts to suit the cognitive task being performed is required for optimal functioning.

The cognitive decline observed in those who later developed Alzheimer's "may be directly related to lack of inhibitory cognitive control," the researchers write.

This suspicion is consistent with a leading hypothesis proposing that Alzheimer's disease, at its earliest stages, is characterised by hyperexcitable neurons.

"Now that we've uncovered beta event features that predict Alzheimer's disease progression, our next step is to study the mechanisms of generation using computational neural modeling tools," says Jones.

"If we can recreate what's going wrong in the brain to generate that signal, then we can work with our collaborators to test therapeutics that might be able to correct the problem."

The study was published in Imaging Neuroscience.