Apolipoprotein E polymorphism and brain morphology in mild cognitive impairment.

Area of Science:

• Neuroimaging
• Genetics
• Neurology

Background:

• Apolipoprotein E (ApoE) genotype is a primary genetic risk factor for late-onset Alzheimer's disease (AD).
• The relationship between ApoE genotype and brain morphology in mild cognitive impairment (MCI), a precursor to AD, is not fully understood.

Purpose of the Study:

• To investigate the association between ApoE genotype and brain structural changes in individuals with MCI.
• To determine if specific ApoE epsilon4 allele dosages correlate with distinct patterns of gray and white matter atrophy in MCI.

Main Methods:

• Utilized optimized voxel-based morphometry (VBM) on 83 subjects diagnosed with MCI.
• Compared gray and white matter densities across three ApoE genotype groups: epsilon4 noncarriers (n=42), one epsilon4 allele carriers (n=27), and two epsilon4 allele carriers (n=14).

Main Results:

• Individuals with two epsilon4 alleles showed significant gray matter density decline in the medial temporal lobe.
• Subjects with one epsilon4 allele exhibited gray matter atrophy in the right inferior frontal gyrus.
• White matter atrophy was observed only in homozygous epsilon4 carriers, localized to the right superior and middle temporal gyrus.

Conclusions:

• Findings support the link between ApoE genotype and structural brain changes in MCI.
• The observed structural alterations in MCI patients with specific ApoE genotypes mirror early AD-related changes.