Delay in word processing may indicate a higher risk of developing Alzheimer's

London: People with mild memory problems who show a delayed brain response to processing the written word may be at an increased risk of Alzheimer's disease, a study has found.

Using an electroencephalogram (EEG) - a test that detects electrical activity in a person's brain via electrodes attached to their scalp - researchers 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 who took part 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 diagnosis of 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 per cent of people aged over 65, research led by the University of Birmingham in the UK has discovered.

"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 Ali Mazaheri from the University of Birmingham in the UK.

"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," said Mazaheri.

"We focused on language functioning, since it is a crucial aspect of cognition and particularly impacted during the progressive stages of Alzheimer's," he said.

Previous research has found that when a person is shown a written word, it takes 250 milliseconds for the brain to process it - activity which 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 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," said Segaert.

"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.