Comparing the Hippocampal Volume Between Patients with Alzheimer’s Disease and Healthy Controls: An MRI Analysis using the Harmonized Hippocampal Protocol

Objective: To compare the hippocampal volume between individuals with normal cognitive function (CN) and those with Alzheimer’s disease (AD) using the European Alzheimer’s Disease Consortium (EADC)-Alzheimer’s Disease Neuroimaging Initiative (ADNI) Harmonized Hippocampal Protocol (HarP). Methods: This retrospective study included 84 participants (42 individuals each in the AD and CN groups) from April 30th Hospital (Ho Chi Minh City, Vietnam). The AD diagnosis adhered to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. Participants underwent neuropsychological tests and whole brain magnetic resonance scans for cognitive function and hippocampal volume assessments. The AD participants were categorized into four subgroups based on the severity of their cognitive decline, determined using the Mini-Mental State Examination scores (AD1: 5=24, AD2: 20-23, AD3: 14-19, and AD4: 0-13). Qualified radiologists used HarP to measure the whole and sectional hippocampal volumes. Statistical analyses were performed to compare the hippocampal volume differences between the AD and CN groups considering disease severity, sex, and age. A multifactor regression analysis was conducted to explore the predictive factors for hippocampal volume. Results: The neuropsychological test findings (p-value < 0.001), but not demographic data (sex, education, body mass index, medical history), were significantly different among the AD subgroups. The whole (AD: 4.158 ± 0.989 cm3; CN: 5.884 ± 0.517 cm3) and sectional hippocampal volumes were significantly different between the AD and CN groups (p-value < 0.0001). Specifically, the whole and sectional hippocampal volumes were significantly different between the AD2 subgroup and CN group (p-value < 0.05). Besides, multifactor regression analysis showed a minimal impact of the demographic factors on the whole hippocampal volume. Conclusion: Our study highlights the association between AD and reduced hippocampal volume, emphasizing its significance in the disease’s pathology. Our data support the effectiveness of the HarP in measuring hippocampal volume.