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The Differentiation of Amnestic Type MCI from the Non-Amnestic Types by Structural MRI
Gábor Csukly1, Enikő Sirály1, Zsuzsanna Fodor1
1Department of Psychiatry and Psychotherapy, Semmelweis University Budapest, Hungary.
Introduction:
While amnestic mild cognitive impairment (aMCI) and non-amnestic mild cognitive impairment (naMCI) are theoretically different entities, only a few investigations studied the structural brain differences between these subtypes of mild cognitive impairment. The aim of the study was to find the structural differences between aMCI and naMCI, and to replicate previous findings on the differentiation between aMCI and healthy controls.
Methods:
Altogether 62 aMCI, naMCI, and healthy control subjects were included into the study based on the Petersen criteria. All patients underwent a routine brain MR examination, and a detailed neuropsychological examination.
Results:
The sizes of the hippocampus, the entorhinal cortex and the amygdala were decreased in aMCI relative to naMCI and to controls. Furthermore the cortical thickness of the entorhinal cortex, the fusiform gyrus, the precuneus and the isthmus of the cingulate gyrus were significantly decreased in aMCI relative to naMCI and healthy controls. The largest differences relative to controls were detected for the volume of the hippocampus (18% decrease vs. controls) and the cortical thickness (20% decrease vs. controls) of the entorhinal cortex: 1.6 and 1.4 in terms of Cohen's d. Only the volume of the precuneus were decreased in the naMCI group (5% decrease) compared to the control subjects: 0.9 in terms of Cohen's d. Significant between group differences were also found in the neuropsychological test results: a decreased anterograde, retrograde memory, and category fluency performance was detected in the aMCI group relative to controls and naMCI subjects. Subjects with naMCI showed decreased letter fluency relative to controls, while both MCI groups showed decreased executive functioning relative to controls as measured by the Trail Making test part B. Memory performance in the aMCI group and in the entire sample correlated with the thickness of the entorhinal cortex and with the volume of the amygdala.
Conclusion:
The amnestic mild cognitive impairment/non-amnestic mild cognitive impairment separation is not only theoretical but backed by structural imaging methods and neuropsychological tests. A better knowledge of the MCI subtypes can help to predict the direction of progression and create targeted prevention.
Insights
Structural brain differences distinguish amnestic mild cognitive impairment (aMCI) from non-amnestic mild cognitive impairment (naMCI). These findings, supported by neuroimaging and neuropsychological tests, aid in predicting disease progression and developing targeted prevention strategies for mild cognitive impairment subtypes.
Area of Science:
- Neuroimaging
- Neurology
- Cognitive Science
Background:
- Mild cognitive impairment (MCI) is categorized into amnestic (aMCI) and non-amnestic (naMCI) subtypes, though their distinct structural brain differences require further investigation.
- Previous research has explored structural brain differences between aMCI and healthy controls, but fewer studies have directly compared aMCI and naMCI.
Purpose of the Study:
- To investigate the structural brain differences between aMCI and naMCI subtypes.
- To validate and replicate previous findings on structural differences between aMCI and healthy controls.
Main Methods:
- Inclusion of 62 subjects diagnosed with aMCI, naMCI, or healthy controls based on Petersen criteria.
- Comprehensive assessment including routine brain Magnetic Resonance (MR) imaging and detailed neuropsychological examinations.
Main Results:
- aMCI patients exhibited reduced hippocampal, entorhinal cortex, and amygdala volumes compared to naMCI and controls.
- Cortical thinning in the entorhinal cortex, fusiform gyrus, precuneus, and cingulate gyrus was significant in aMCI versus naMCI and controls.
- naMCI group showed a 5% decrease in precuneus volume compared to controls, while aMCI patients had significant memory and fluency deficits and reduced executive functioning.
Conclusions:
- The distinction between aMCI and naMCI is supported by structural neuroimaging and neuropsychological data.
- Understanding MCI subtypes through advanced methods can improve prediction of disease progression.
- This research paves the way for developing targeted prevention strategies for different MCI subtypes.
