Association of Serum Homocysteine and Vitamin B12 with Different Grades of Cognitive Impairment in Alzheimer's Disease Patients

BACKGROUND: Studies have shown a relation between Vitamin B12 (B12) and cognitive impairment in Alzheimer's disease (AD). However, B12 levels do not indicate the severity of the disease. High homocysteine-induced neuroinflammation has been related to the pathogenesis of AD. AIM: This study aimed to determine the correlation of Vitamin B12 and serum homocysteine with the cognitive status of AD patients. MATERIALS AND METHODS: AD patients (n = 25) and healthy controls (n = 25) were recruited for this study. The revised criteria for diagnosis and staging of AD were used for the diagnosis of AD. Clinical history, laboratory investigations (B12, homocysteine, lipid profile, C-reactive protein, and serum creatinine), and Mini-Mental Status Examination (MMSE) were done. Based on MMSE score, AD patients were subdivided into four groups. All statistical analyses were done on IBM SPSSv26. RESULTS: In AD patients, B12 was lower (221.3 ± 54.5 vs. 396.6 ± 88.4 pg/ml, P = 0.00), serum homocysteine was higher (15.2 ± 4.6 vs. 11.7 ± 2.3 µmol/L, P = 0.00), and C-reactive protein was higher (0.95 ± ± 0.39 vs. 0.69 ± 0.12 mg/dl, P = 0.00). Among the four AD groups, we observed a gradual increase in the serum homocysteine levels with a decline in the cognitive status (lower MMSE score) (F = 13.32, P = 0.00). MMSE score had a statistically significant correlation with homocysteine (ρ = -0.85, P = 0.00), unlike B12 (ρ =0.33, P = 0.11). CONCLUSION: Serum homocysteine is a better diagnostic indicator of cognitive impairment than B12. In resource-limited settings, screening with the Mini-Cog test and timely supplementation with B complex vitamins (B6, B12, and folic acid) can slow the progress of dementia in AD patients.