Structural disruption in subjective cognitive decline and mild cognitive impairment

Area of Science:

• Neuroimaging
• Neurology
• Alzheimer's Disease Research

Background:

• Subjective cognitive decline (SCD) represents the earliest stage of the Alzheimer's disease continuum.
• Existing research on brain structural changes in SCD is inconsistent, necessitating further investigation.

Purpose of the Study:

• To investigate and compare structural brain alterations in individuals with SCD, mild cognitive impairment (MCI), and healthy controls (HC).
• To identify specific morphological and microstructural differences associated with cognitive decline.

Main Methods:

• Recruited 37 SCD patients, 28 MCI patients, and 42 HC.
• Analyzed T1- and diffusion-weighted MRI images for morphological and microstructural differences.
• Utilized support vector machines (SVM) for classification analysis based on MRI features.

Main Results:

• Both SCD and MCI groups exhibited reduced left inferior parietal lobe (IPL) volume compared to HC.
• SCD patients showed altered morphology in the right inferior temporal gyrus (ITG), insula, and amygdala compared to MCI.
• Microstructural changes in fiber tracts of the right ITG, lateral occipital cortex (LOC), and insula were observed in SCD relative to MCI.
• Left IPL volume, right LOC volume, right amygdala volume, and right LOC fiber tract diffusivity correlated significantly with cognitive functions.

Conclusions:

• SCD and MCI share common atrophy in the left IPL.
• Distinct morphological and microstructural differences exist in cortical-subcortical areas between SCD and MCI.
• MRI-based classification models achieved high accuracy (>0.7, AUC=0.8) in differentiating these groups.