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

Background: Clinical subtypes of mild cognitive impairment (MCI)
may represent different underlying aetiologies. Methods: This
European, multicentre, memory clinic based study (DESCRIPA) of
non-demented subjects 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. Results:
Severity of MTA differed between MCI subtypes (p,0.001), increasing
from a mean of 0.8 (SD 0.7) in subjective complaints (n=77) to 1.3
(0.8) in nonamnestic MCI (n=93), and from 1.4 (0.9) in single
domain amnestic MCI (n=70) to 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 of age.
Severity of WMH did not differ between MCI subtypes (p=0.21).
However, the combination of MTA and WMH differed between MCI
subtypes (p=0.02) Conclusion: 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 the underlying cause. In nonamnestic MCI, the
relatively higher prevalence of MTA in combination with WMH may
suggest a different pathophysiological origin.