Affiliations: [a] School of Life Sciences, University of Technology Sydney, NSW, Australia
| [b] Department of Neurophysiology, Liverpool Hospital, NSW, Australia
| [c] A Healthy Step Clinic, NSW, Australia
| [d] Ingham Institute for Applied Medical Research, Liverpool, NSW, Australia
Correspondence:
[*]
Correspondence to: Kaneez Fatima Shad, School of Life Sciences,
University of Technology Sydney, 15 Broadway, Ultimo, NSW 2007,
Australia. Mailing address: PO Box 123, Broadway NSW 2007,
Australia. Tel.: +61432064886; E-mails:
[email protected]; [email protected].
Abstract: Brain stem neural tracts and nuclei may be disturbed prior to observable neuronal atrophy in AD. In this perspective, we discuss the notion of functional deficits presenting prior to structural abnormalities in Alzheimer’s disease (AD). Imaging of inferior colliculi using magnetic resonance spectroscopy (MRS) shows significant decrease in the neuronal markers, N acetyl aspartate/creatine ratio and increase in the glial marker myo-Inositol, in subjects with Mini-Mental State Examination scores greater than 24 and with no signs of atrophy in their MRI of the medial temporal lobe. Abnormalities in components of the auditory event-related potentials (ERPs) are described in cognitive impairment including AD. We observed a significant decrease in amplitude and increase in latency during the first 10 ms of auditory evoked potentials measured on electroencephalography (EEG) indicating slow auditory response of the brainstem. EEG spectral power recorded at the cortex is also associated with neural activity at the level of the inferior colliculi. We postulate that a functional examination of auditory afferent pathways, using non-invasive techniques, such as MRS, brain stem auditory evoked potentials (BAEPs) and ERPs may improve diagnostic accuracy of AD. Functional changes precede structural changes and it is important to further understand the relationship between biochemical and electrophysiological measures such as MRS, BAEPs and EEG.
