Impact of subclinical hypothyroidism on cognitive functions among the elderly.

Abstract

BackgroundThe association of thyroid dysfunction with alterations in mood and cognition has been recognized since some of the earliest descriptions of the disease. Most recent cross-sectional and longitudinal studies have failed to find an association between cognitive dysfunction and subclinical hypothyroidism (SCH). A recent paper from our country however suggested a significant association. ObjectivesThis study was undertaken to determine the prevalence and risk of cognitive impairment among educated, elderly Indian patients (>60 years) with SCH. Materials and MethodsThis study was conducted among educated, elderly patients admitted to Christian Medical College and Hospital, Ludhiana, Punjab, India. Patients with SCH and an equal number of controls were interviewed after taking informed consent. SCH was defined as serum thyroid stimulating hormone (TSH) level more than 4.0 mIU/L with serum free triiodothyronine (FT3) and free thyroxine (FT4) in the normal reference range. Cognitive function was assessed by Hindi mini mental status examination (HMSE) and clock drawing test (CDT). ResultsThe cases (n=100) had a mean age of 68.2 years, there were 59% males, and had a mean body mass index of 25.5kg/m2 compared to controls (n=100) who had a mean age of 69.9 years (p=0.09), there were 64% males (p=0.5), and had a mean BMI of 25.3 kg/m2 (p=0.7) which were all comparable. All other baseline variables including co-morbidities, family history of dementia, head injury, smoking, alcohol use, fruit and vegetable intake, daily newspaper reading, education and exercise regularity were comparable in both groups. The cases and controls had mean HMSE of 26.1 and 25.9 (p=0.68) respectively, and the cases and controls had mean CDT of 2.19 and 2.18 (p=0.95) respectively. ConclusionsThere is no difference in cognitive function in older patients with SCH in comparison with those without SCH