Prevalence of hypothyroidism in older adults and its association with cognition: a cross-sectional study from a South Indian ageing urban cohort.

The study conducted on a South Indian urban cohort aimed to emphasize the prevalence and patterns of hypothyroidism and its association with cognition among individuals aged 45 years and above. A cross-sectional design was adopted, utilizing data from the Tata Longitudinal Study of Aging cohort, comprising 1201 non-demented participants in Bangalore, South India. The study contains detailed clinical assessments, including medical history, physical examination and cognitive tests such as the COGNITO battery, Hindi Mental State Examination and Addenbrooke's Cognition Examination III. Biochemical tests were utilized to quantify plasma levels of thyroid-stimulating hormone, triiodothyronine and thyroxine. Participants were categorized based on medication history and thyroid hormone levels. The study findings showed a 17.69% prevalence of hypothyroidism, with 6.22% being classified as overt hypothyroidism and 93.78% as subclinical hypothyroidism. The prevalence was significantly higher in females compared with males ( = 0.043). Individuals with hypothyroidism are more frequently diagnosed with mild cognitive impairment than people with euthyroid ( = 0.008). Furthermore, on the classification based on thyroid medication history, the ineffective treatment group performed poorer in Addenbrooke's Cognition Examination III fluency ( = 0.006), auditory attention ( = 0.001) and form matching ( = 0.024) tasks compared with the adequately treated group. The partially treated group performed poorer in visual attention ( = 0.005) and vocabulary ( = 0.043) compared with the effectively treated group. The study identified a notable prevalence of hypothyroidism in the cohort, with females exhibiting a higher prevalence. Our study suggests that the timely management of thyroid disorders with medications is crucial not only to prevent hormonal imbalances but also to improve cognitive functioning.