White matter hyperintensities and medial temporal lobe atrophy in clinical subtypes of mild cognitive impairment: the DESCRIPA study

Abstract

Clinical subtypes of mild cognitive impairment (MCI) may represent different underlying aetiologies. In a European, multi-center, memory-clinic based study (DESCRIPA) of non-demented subjects we investigated whether MCI subtypes have different brain correlates on MRI and whether the relation between subtypes and brain pathology is modified by age. Using visual rating scales medial temporal lobe atrophy (MTA) (0-4) and white matter hyperintensities (WMH) (0-30) were assessed. Severity of MTA differed between MCI subtypes (p<0.001), increasing from (mean±standard deviation) 0.8±0.7 in subjective complaints (n=77), to 1.3±0.8 in non-amnestic MCI (n=93), 1.4±0.9 in single-domain amnestic MCI (n=70) and 1.7±0.9 in multiple-domain amnestic MCI (n=89). The association between MCI subtype and MTA was modified by age, and mainly present in subjects >70 years. Severity of WMH didn’t differ between MCI subtypes (p=0.21), However, the combination of MTA and WMH differed between MCI subtypes (p=0.02) We conclude that MCI subtypes may have different brain substrates, especially in older subjects. Isolated MTA was mainly associated with amnestic MCI subtypes, suggesting AD as underlying cause. In non-amnestic MCI the relatively higher prevalence of MTA in combination with WMH may suggest a different pathophysiological origin.