Effect of Donepezil and Vitamin B12 Supplement on Serum Thyroid Profile in Alzheimer’s Disease

Aims: The aim of this study was to investigate thyroid status in Alzheimer’s Disease (AD) patients and its response to donepezil and vitamin B12 supplement therapy for 6 months.

Design: Case-Control Observational study.

Place and Duration: Department of Biochemistry, GGMC & Sir J. J. Group of Hospitals, Mumbai, India between March 2017 and July 2019.

Methodology: Case-Control study comprised of 71 AD patients and 70 healthy controls above 60 years of age. Blood serum samples were analyzed for thyroid hormones levels by the chemiluminescence method. AD patients were treated with donepezil (5 mg/day) and vitamin B12 supplement (1.5 mg/day) and thyroid profile was observed at intervals of 3 and 6 months. Statistical evaluation was done by using IMB SPSS statistics version 25.

Results: Serum levels of thyroid hormones were low in euthyroid AD patients when compared with controls at the baseline level [T3 (120.64 ± 20.64 vs 127.8 ± 17.29), T4 (7.71 ± 2.34 vs 7.54 ± 1.85), FT3 (1.2 ± 0.13 vs 2.26 ± 0.63) and FT4 (0.79 ± 0.08 vs 1.29 ± 0.27)] except TSH which was increased in AD [TSH (2.71 ± 1.19 vs 2.34 ± 0.65)]. During follow-ups at 3 and 6 months, there was a slight decrease in TSH levels in response to the therapy.

Conclusion: The AD patients were euthyroid with low T3, FT3 and FT4 serum levels and high TSH serum levels. Thyroid hormones might play a role as markers for disease progression. Donepezil and vitamin B12 therapy could not benefit restore the normal thyroid functioning in a period of 6 months. Further longitudinal research with larger cohort might help in elucidating thyroid dysfunction in AD and develop novel therapeutic strategies.