MR signal abnormalities in memory disorder and dementia

Area of Science:

• Neurology
• Radiology
• Gerontology

Background:

• White-matter hyperintensities on MRI are observed in aging and dementia.
• Differentiating between Alzheimer disease and vascular dementia is clinically important.

Purpose of the Study:

• To investigate the correlation between white-matter lesions on MRI and cognitive status.
• To determine if lesion location and type can differentiate between Alzheimer disease and multi-infarct dementia.

Main Methods:

• Brain MRI was performed on 86 normal subjects and 113 patients with memory disorders.
• Lesions were categorized by size and location (periventricular, subcortical, cortical).
• Patients were classified using Hachinski ischemic scores for probable/possible Alzheimer disease, mixed, or multi-infarct dementia.

Main Results:

• Significant positive correlations were found between age and periventricular/subcortical lesions in normal subjects.
• Hachinski ischemic scores correlated with periventricular, subcortical, and cortical lesions in patients with memory disorders.
• Periventricular lesions were highly prevalent in both Alzheimer disease and multi-infarct dementia.
• Subcortical lesions were more prevalent in multi-infarct dementia (100%) compared to Alzheimer disease (approx. 50%).

Conclusions:

• White-matter abnormalities on MRI are associated with age and cognitive decline.
• Subcortical lesion scores are more effective than periventricular lesion scores in distinguishing vascular dementia from Alzheimer disease.
• Prominent subcortical white-matter abnormalities on MRI suggest a higher likelihood of vascular dementia.