Correlation between overt hyperthyroid and subclinical hyperthyroid and cognitive impairment in Dr. Sardjito General Hospital, Yogyakarta, Indonesia

Abstract

Hyperthyroidism is a metabolic imbalance resulting from excessive production of thyroid hormones.
Overt or subclinical hyperthyroid prevalence has reached 20%. The differences in thyroid status
induce apoptosis in adult cerebral cortex. Triiodothyroxine (T3) acts directly on the cerebral
cortex mitochondria and induces the release of cytochrome-c which leads to apoptosis. The
increase of hormone levels encountered in hyperthyroidism which is associated with an increase
in necrotic death of neurons and oxidative stress has a negative effect on cognition. Several
studies demonstrated the significant association of hyperthyroidism with cognitive impairment,
despite remaining as controversial results. The study aimed to evaluate the correlation between
overt hyperthyroid and subclinical hyperthyroid and cognitive impairment in hyperthyroidism
patients. This was a cross-sectional study involving 68 patients of hyperthyroidism who were
treated in Endocrine Clinic of Dr. Sardjito General Hospital, Yogyakarta. The inclusion criteria
were hyperthyroidism based on anamnesis, clinical examination and laboratory tests, age of 20-
60 years, symptoms of hyperthyroidism, and minimum education of elementary school. The
relationship of hyperthyroidism and cognitive impairment, and multivariate analysis was analyzed
by Chi-square and logistic regression tests, respectively. The results were considered as statistically
significant if the value of p was <0.05. The results showed that overt hyperthyroidism had
significantly associated with cognitive impairment (p = 0.021). Another variable associated
with cognitive impairment was female gender (p = 0.019). In a multivariate analysis, the variables
of overt hyperthyroidism (p = 0.024) and sex (p = 0.025) had independent association with
cognitive impairment. In conclusion, this study found that overt hyperthyroidism had a significant
association with incidence of cognitive impairment compared to subclinical hyperthyroidism.

Keywords: hyperthyroidism - overt - subclinical - cognitive - mini-mental state examination