Isolated, Subtle, Neurological Abnormalities in Mild Cognitive Impairment Types.

Background: Isolated, subtle neurological abnormalities (ISNA) are commonly seen in aging, and have been related to cerebral Small Vessel Disease (SVD) and subcortical atrophy in neurologically and cognitively healthy aging subjects. Objective: To investigate the frequency of ISNA in different MCI types, and to evaluate for each MCI type the cross-sectional relation between ISNA and white matter hyperintensities (WMH), lacunes, caudate atrophy, and ventricular enlargement. Methods: 1,250 subjects with different MCI types were included in the analysis, and underwent brain MRI. WMH were assessed through two visual rating scales. Lacunes were also rated. Atrophy of the caudate nuclei and ventricular enlargement were assessed through the bicaudate ratio (BCr) and the lateral ventricles to brain ratio (LVBr), respectively. Apolipoprotein E (APOE) genotypes were also assessed. The routine neurological examination, and the items of Part-III of the Unified Parkinson's Disease Rating Scale were used to evaluate ISNA that were clustered as central-based signs, mild parkinsonian signs, cerebellar-based signs, and primitive reflexes. Associations of ISNA with imaging findings was determined through logistic regression analysis. Results: The ISNA increase with the age, are present in all MCI types, particularly in those multiple domains, and carrying the APOE ?4 allele, and are associated with WMH, lacunes, BCr, and LVBr. Conclusion: This study demonstrates that cortical and subcortical vascular and atrophic processes contribute to ISNA. Long prospective population-based studies are needed to disentangle the role of ISNA in the conversion from MCI to dementia.