Thyroid disorders not tied to Cognitive impairment or dementia: JAMA

Dr. Nicolien and colleagues have found in a new study that subclinical hypothyroidism and hyperthyroidism were not associated with cognitive function, cognitive decline, or incident dementia. These findings do not support the need for screening for subclinical thyroid dysfunction for prevention of cognitive decline or dementia. These findings were published in JAMA Journal of Internal Medicine on 07 September, 2021.

Overt and subclinical thyroid disorders are recognized as causative and therapeutic factors for cognitive impairment in clinical recommendations.

In this individual participant data study included over 74 000 people. The researchers focused this study to investigate the cross-sectional and longitudinal relationships between baseline thyroid dysfunction and cognitive function and dementia.

Between 1989 and 2017, this multicohort individual participant data study examined 114 267 person-years of follow-up for cognitive function and 525 222 person-years for dementia. The cognitive function analyses included 21 cohorts with a total of 38 144 individuals. The dementia analyses included eight cohorts with a total of 2033 dementia cases and 44 573 controls. From December 2016 to January 2021, overall data was analysed.

The study findings included:

Subclinical thyroid dysfunction was not linked with global cognitive performance at baseline or yearly decrease in this individual participant data study. These data do not support the necessity for subclinical thyroid dysfunction monitoring to avoid cognitive decline or dementia.

Previous study-level meta-analyses found no link between subclinical hypothyroidism and cognitive function, cognitive decline, or dementia, they were restricted by variability in thyroid dysfunction diagnoses and covariate selections in statistical models.

Younger individuals and women may be more vulnerable to cognitive dysregulation associated with thyroid disease.

The chance of overtreatment is considerable, which increases the risk of atrial fibrillation, atherosclerosis, and cerebral infarction and thereby might increase the risk of cognitive decline.

Subclinical hypothyroidism and hyperthyroidism were not related with cognitive function, Cognitive decline, or incident dementia.

"There is insufficient evidence to draw firm conclusions on the impact of overt thyroid dysfunction in dementia risk. These data do not support the practice of screening for subclinical thyroid disease in older individuals in the setting of cognitive loss, as advised by current guidelines," said the Author in conclusion.

Reference:

van Vliet NA, van Heemst D, Almeida OP, et al. Association of Thyroid Dysfunction With Cognitive Function: An Individual Participant Data Analysis. JAMA Intern Med. Published online September 07, 2021. doi:10.1001/jamainternmed.2021.5078