Neuroanatomical Variations and Their Influence on Cognitive Functions

Background: Neuroanatomical variations are increasingly recognized for their role in influencing cognitive functions, particularly in individuals with subjective cognitive decline (SCD). Structural differences in gray matter (GM) and white matter (WM) volumes, as well as cortical thickness, may underlie the cognitive impairments observed in SCD. Understanding these neuroanatomical changes is crucial for early detection and intervention strategies in cognitive decline. Objective: This study aimed to investigate the neuroanatomical variations between individuals with SCD and healthy controls and to examine the impact of these variations on cognitive functions. Methods: The study was conducted at the Faculty of Rehabilitation Sciences, Lahore University of Biological and Applied Sciences, Pakistan. A total of 42 participants were included, with 21 individuals in the SCD group and 21 in the control group. Participants were recruited through advertisements and referrals, and inclusion criteria for the SCD group included individuals aged 60 and above with self-reported cognitive concerns but no objective impairment on neuropsychological tests. Neuroimaging data were acquired using a 3.0 Tesla MRI scanner, and high-resolution T1-weighted images were analyzed using Statistical Parametric Mapping (SPM) software version 12 and FreeSurfer software. Cognitive function was assessed using the Mini-Mental State Examination (MMSE), Trail Making Test (TMT) Parts A and B, California Verbal Learning Test (CVLT), and Boston Naming Test (BNT). Data analysis was performed using SPSS version 25, with independent t-tests and chi-square tests to compare groups and ANCOVA to adjust for confounders. Effect sizes were calculated using Cohen’s d. Results: Significant differences were observed between the SCD and control groups in several neuroanatomical measures. Individuals with SCD had reduced GM volume in the anterior cingulate cortex (R, p=0.018; L, p=0.025), midcingulate cortex (R, p=0.037), and middle frontal gyrus (L, p=0.030). Significant reductions in WM volume were also found in the inferior frontal gyrus (L, p=0.028) and postcentral gyrus (L, p=0.047). Cortical thickness was significantly reduced in the inferior temporal gyrus (L, p=0.0002; Cohen’s d=1.06), entorhinal cortex (L, p=0.008; Cohen’s d=1.03), and middle temporal gyrus (R, p=0.0004; Cohen’s d=1.02). Cognitive assessments revealed that the SCD group had significantly lower scores on the MMSE (p=0.294, d=0.33), GDS-15 (p=0.001, d=-1.08), and subjective cognitive complaints from patients (p<0.001, d=-2.89). Conclusion: The study found significant neuroanatomical differences between individuals with SCD and healthy controls, particularly in GM and WM volumes and cortical thickness. These structural variations were associated with cognitive impairments observed in the SCD group, underscoring the importance of early detection and targeted interventions. Future research should focus on longitudinal studies and the integration of biomarkers to enhance the understanding of neuroanatomical changes in cognitive decline. Keywords: Neuroanatomical Variations, Subjective Cognitive Decline, Gray Matter Volume, White Matter Volume, Cortical Thickness, Cognitive Functions, MRI, Neuroimaging, Early Detection, Cognitive Decline.