[Effect of apolipoprotein E genotype on magnetic resonance spectrum in amnestic mild cognitive impairment and Alzheimer's disease patients].

Objective

To explore the relationship between apolipoprotein E (ApoE) gene polymorphism and hydrogen proton magnetic resonance spectroscopy ((1)H-MRS) in patients with Alzheimer's disease (AD) and amnestic mild cognitive impairment(aMCI).

Methods

The cognitive function of 35 AD patients (AD group), 35 aMCI patients (aMCI group) and 36 normal controls (NC group) were evaluated by neuropsychological scales, including Mini-mental State Examination (MMSE) and Cambridge Cognitive Examination-Chinese version (CAMCOG-C). The genotypes of ApoE were analyzed by high-resolution melting assay. Brain regional metabolites were measured via (1)H-MRS technique with the regions of interest (ROIs) located in the left frontal lobe and left hippocampus.

Results

The CAMCOG-C (NC group 94.00 (8.50);aMCI group 86.00(8.00);AD group 61.00(18.0)) and MMSE (NC group 29.00 (2.00);aMCI group 26.00(2.00);AD group 13.00(9.5)) scores in AD and aMCI group were significantly lower in comparison with that in NC group (P<0.05). There was multi-domain cognitive impairment both in AD and aMCI. The CAMCOG-C (ε4 carriers 76.00(28.00);no-ε4 carriers 89.00 (17.00)) and MMSE (ε4 carriers 23.00(16.00);no-ε4 carriers (27.00 (6.00))scores in ε4 carriers were significantly lower than those in no-ε4 carriers (P<0.05). The AD and aMCI groups showed decreased NAA/Cr ratio in the left hippocampus as well as elevated Cho/Cr ratio and MI/Cr in the left frontal lobe compared to the NC group (P<0.05). This change was even more pronounced in AD group when compared to aMCI group. The NAA/Cr ratio and Cho/Cr ratio in the left hippocampus in ε4 carriers were lower, the MI/Cr ratio in left frontal lobe in ε4 carriers was higher (P<0.05).

Conclusions

ApoE gene polymorphism affects the alteration of (1)H-MRS in AD and aMCI patients. The combination of ApoE gene polymorphism and (1)H-MRS may be more useful to differentiate and diagnose AD and aMCI early.