Seniors whose brains take longer to process written words may go on to develop Alzheimer's disease.
In fact, the National Institute on Aging estimate that 8 in 10 people with MCI are diagnosed with Alzheimer's disease within 7 years of their MCI diagnosis. But what goes on in the brain between being diagnosed with MCI and being diagnosed with Alzheimer's?
Researchers from the University of Birmingham, the University of Kent — both in the United Kingdom — and the University of California, Davis set out to investigate this in their new study.
Lead study author Dr. Ali Mazaheri, of the University of Birmingham, explains the rationale for the investigation.
He says, "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."
"We wanted to investigate," Dr. Mazaheri continues, "if there were anomalies in brain activity during language processing in MCI patients which could provide insight into their likelihood of developing Alzheimer's."
"We focused on language functioning, since it is a crucial aspect of cognition and particularly impacted during the progressive stages of Alzheimer's," he explains.
Brain response to words may be 'crucial'
Previous studies have shown that it takes the brain of an average person 250 milliseconds to process a written word. The brain activity associated with word processing can be seen on an electroencephalogram (EEG), which is a procedure that measures the electrical activity of one's brain by placing tiny electrodes on the scalp.
For the current research, Dr. Mazaheri and his colleagues used an EEG to study the brain activity of 25 participants while they were shown words on a computer screen.
Participants comprised healthy seniors and elders diagnosed with MCI, as well as MCI patients who had received an Alzheimer's diagnosis within 3 years of being diagnosed with MCI.
Study co-author Dr. Katrien Segaert, also of the University of Birmingham, sums up the findings, saying, "Crucially, [we found] 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."
"Our findings were unexpected," she adds, "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," explains Dr. Segaert.
She also shares some directions for future research, saying, "We hope to now test the validity of this biomarker in [a] large population 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 noninvasive test using EEG as part of a routine medical evaluation when a patient first presents to their GP with concern over memory issues."
Dr. Katrien Segaert