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Neurological delays during word processing may predict Alzheimer’s disease

Delayed neurological response to word processing may indicate increased risk for Alzheimer’s disease among individuals with mild cognitive impairment.

“We wanted to investigate if there were anomalies in brain activity during language processing in [mild cognitive impairment] patients which could provide insight into their likelihood of developing Alzheimer’s,” Ali Mazaheri, PhD, of the University of Birmingham, England, said in a press release. “We focused on language functioning, since it is a crucial aspect of cognition and particularly impacted during the progressive stages of Alzheimer’s.”

To assess associations between subtle anomalies in EEG activity among patients with mild cognitive impairment (MCI) and conversion to Alzheimer’s disease, researchers evaluated 25 individuals with amnestic MCI, a subset of individuals who developed Alzheimer’s disease within 3 years and 11 elderly controls. Study participants completed a word comprehension task while researchers monitored EEG activity. The tasks consisted of auditory category descriptions, such as “type of wood” followed by a single visual target word that corresponded to the category, such as “oak,” or did not.

Participants who converted from MCI to Alzheimer’s disease exhibited decreased early posterior-parietal theta activity during first presentation of the target word, compared with participants with MCI who did not convert to Alzheimer’s disease and controls.

Further, participants with MCI who converted to Alzheimer’s disease exhibited different oscillatory signatures for processing corresponding words that were different from non-converters and controls.

All participants with MCI exhibited inconsistent oscillatory signatures for verbal learning/memory of repeated words.

“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,” study researcher Katrien Segaert, PhD, of the University of Birmingham, said in the release. “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 validity of this biomarker in a large population study of patients in the United Kingdom to determine if it is a specific predictor of Alzheimer’s disease or a general marker of dementia. – by Amanda Oldt

Disclosures: The authors report no relevant financial disclosures.