Impaired preconscious auditory processing and cognitive functions in Alzheimerʹs disease

Objective: To study whether preconscious auditory processing is deteriorated in patients with Alzheimerʹs disease (AD) having mild to moderate cognitive symptoms. To investigate whether auditory processing correlates with the impairment of the higher cortical functions. Methods: P50m and N100m responses elicited by a sequence of repetitive tones were recorded with a whole-head magnetometer from 22 patients with probable AD and from 18 healthy age-matched controls. In addition, an extensive neuropsychological test battery assessing main cognitive domains was administered to all subjects. Results: The patients with AD had significantly delayed N100m responses in the left hemisphere that correlated with the impairment of the language functions. Conclusions: N100m auditory responses measured with magnetoencephalography may be useful in evaluating the severity and progression of the cortical dysfunction in dementia.