2022, Vol. 5, Issue 2, Part A

Background and Objectives: Alzheimer's dementia (AD) and late-life depression (LLD) are prevalent neuropsychiatric illnesses linked to cognitive deficits and emotional disturbances. Both disorders have been associated with structural brain changes, especially with the loss of gray matter (GM). Nonetheless, differentiating disease-specific from overlapping patterns of GM atrophy continues to pose a problem. This study sought to examine and evaluate alterations in gray matter volume across patients with Alzheimer's disease and depression by voxel-based morphometry (VBM), while also investigating their correlations with cognitive and clinical assessments.

Materials and Methods: There were 50 volunteers in all, and they were split into three groups: 20 patients with Alzheimer's disease (average age: 70.8 ± 6.3 years), 20 patients with severe depressive disorder (average age: 68.9 ± 7.1 years), and 10 healthy controls who were the same age and sex as the patients (average age: 69.4 ± 6.8 years). The Madha Medical College in Kovur, Chennai, India, was the site of this study from January 2021 to December 2021. All subjects had high-resolution T1-weighted MRI scans on a 3.0 Tesla scanner. Using voxel-based morphometry and Statistical Parametric Mapping software (SPM12), we processed and evaluated structural images.

Results: Patients with Alzheimer's disease exhibited substantial gray matter reductions in the bilateral hippocampus, parahippocampal gyrus, posterior cingulate cortex, and precuneus compared to healthy controls (p < 0.001, FWE-corrected). In depressive patients, glutamate depletion was most pronounced in the left dorsolateral prefrontal cortex, anterior cingulate cortex, and insula (p < 0.005, uncorrected). By juxtaposing the two groups, we saw that individuals with Alzheimer's Disease demonstrated more pronounced atrophy in the parietal and hippocampal regions, whereas those with depression revealed more significant thinning of the prefrontal cortex. The hippocampal gray matter volume exhibited a positive correlation with MMSE scores (r = 0.64, p = 0.002) and a negative correlation with HAM-D scores (r = ?0.58, p = 0.004).

Conclusion: The study indicates that Alzheimer's disease and depression lead to reductions in gray matter volume, which are distinct yet partially intersecting. Depression is characterized by changes in the structure of the fronto-limbic cortex, while Alzheimer's disease is characterized by extensive atrophy of the medial temporal and parietal lobes. These findings support the notion that neurodegeneration and affective dysregulation have a common neurological foundation, while also indicating a method to differentiate between the two disorders based on the extent of gray matter involvement in each.