The effect of L-thyroxine treatment on memory quotient in adults with subclinical hypothyroidism: A randomized double blind controlled trial

Introduction: Verbal memory and executive function might be disturbed in subclinical hypothyroidism. The aim of this study was to explore the effect of levothyroxine treatment on the memory quotient of Anti-TPO-Ab positive subjects with subclinical hypothyroidism. Materials and Methods: Sixty Anti-Tpo-Ab positive subjects (51 female, 9 male) with subclinical hypothyroidism with a mean age of 34 were enrolled in this randomized double blind placebo controlled trial. Subjects were randomized into two groups, i.e. the case (26 females- 4 males) and the controls (25 females, 5 males) groups. Using the Weschler memory test, memory quotient was assessed at the beginning and three months after initiation of levothyroxine treatment. Results: The mean age of subjects was 34.22±10.75 y and the mean TSH level was 8.25±3.64 mIU/l. There was no difference between two groups in relation to the memory quotient at the beginning of the study (10.5.70±11.66 vs 105.87±11.49, P=0.83). Following treatment the mean for the memory quotient rose by 9.9±8.01 in the cases and 3.23±7.63 in the controls (P=0.002). Conclusion: In this study we observed an increase in the memory quotient after treatment with levothyroxine in individuals with subclinical hypothyroidism, demonstrating that levothyroxine treatment could be recommended to improve verbal memory and executive function in this group of subjects.