Association between dementia and elevated TSH: A community-based study

We report on 194 individuals (96 men and 68 women), aged 65 and over, who had dementia assessments and basal TSH measurements as part of an ongoing epidemiological study of dementing disorders in larger population. Dementia was diagnosed according to DSM-III-R and measured by the Clinical Dementia Rating scale; CDR scores of 0, 0.5, and greater than or equal to 1, represent individuals with no dementia (n = 122), possible dementia (n = 29), and definite dementia (n = 43), respectively. The odds ratio for the association of elevated TSH with definite dementia (CDR greater than or equal to 1) was 3.8 (95% confidence interval = 1.6, 9.2), after adjusting for the effects of age, gender, and level of education. This is the first community-based study to report as association between TSH elevation and dementia. Our findings are consistent with recent evidence that subclinical hypothyroidism is associated with cognitive impairment, and that thyroidal state may influence cerebral metabolism.