Atrophy of the auditory cortex in Alzheimer's disease

To characterize the auditory cortex (AC) in patients with Alzheimer's Disease (AD) and to assess the effect of ageing using Magnetic Resonance Imaging.

Multicenter, cross-sectional study. Data from the Alzheimer's Disease Neuroimaging Initiative (ADNI) were analyzed, including 200 patients with AD, 200 elderly controls, and 200 individuals with Mild Cognitive Impairment (MCI). Volumes of the Heschl's gyrus, Planum Temporale and Planum Polare-corresponding to the primary, secondary and association AC, respectively- were obtained using Freesurfer. Regional volumes were normalized to intracranial volume and compared between groups, considering age and sex.

Patients with AD showed significantly lower AC volumes compared with individuals with MCI and elderly controls. In addition, AC volumes declined with increasing age, though this reduction was less pronounced in the left Planum Temporale and left Heschl's gyrus of AD patients. In multivariate analysis, both age and AD diagnosis were independent negative predictors, with the effect of AD being more pronounced, even after adjusting for age.

The AC is significantly affected in AD. Furthermore, AC volumes decline with ageing across all regions, although the reduction is less evident in the secondary AC and left primary AC of AD patients. Patients with MCI showed relative preservation of the primary AC and left secondary AC compared with AD patients.