Delayed Word Processing May Predict Risk of Alzheimer's

A delayed neurological response to processing the written word could be an indicator that a patient with mild memory problems is at an increased risk of developing Alzheimer’s disease, according to new research.

Using an electroencephalogram (EEG) — a test that detects electrical activity in a person’s brain via electrodes attached to their scalp — researchers at the University of Birmingham, the University of Kent, and the University of California studied the brain activity of a group of 25 patients to establish how quickly they processed words shown to them on a computer screen.

The patients were a mix of healthy elderly people, patients with mild cognitive impairment (MCI), and patients with MCI who had developed Alzheimer’s within three years of being diagnosed with MCI.

MCI, a condition in which someone has minor problems with mental abilities such as memory beyond what would normally be expected for a healthy person of their age, is estimated to be suffered by up to 20 percent of people over 65. It is not a type of dementia, but a person with MCI is more likely to go on to develop dementia, researchers noted.

“A prominent feature of Alzheimer’s is a progressive decline in language, however, the ability to process language in the period between the appearance of initial symptoms of Alzheimer’s to its full development has scarcely previously been investigated,” said Dr. Ali Mazaheri of the University of Birmingham.

“We wanted to investigate if there were anomalies in brain activity during language processing in MCI patients which could provide insight into their likelihood of developing Alzheimer’s.”

He noted the researchers focused on language functioning, since it is a crucial aspect of cognition and is particularly impacted during the progressive stages of Alzheimer’s.

Previous research has found that when a person is shown a written word, it takes 250 milliseconds for the brain to process it, activity that can be picked up on an EEG.

“Crucially, what we found in our study is that this brain response is aberrant in individuals who will go on in the future to develop Alzheimer’s disease, but intact in patients who remained stable,” said Dr. Katrien Segaert of the University of Birmingham.

“Our findings were unexpected as language is usually affected by Alzheimer’s disease in much later stages of the onset of the disease. It is possible that this breakdown of the brain network associated with language comprehension in MCI patients could be a crucial biomarker used to identify patients likely to develop Alzheimer’s disease.”

Researchers hope to test the validity of the biomarker in a large group of patients in the U.K. to see if it’s a specific predictor of Alzheimer’s disease or a general marker for dementia involving the temporal lobe.

“The verification of this biomarker could lead the way to early pharmacological intervention and the development of a new low cost and non-invasive test using EEG as part of a routine medical evaluation when a patient first presents to their GP with concern over memory issues,” Segaert added.

The study was published in Neuroimage Clinical.

Source: The University of Birmingham