Table 1.
Description of Included Studies for the Effect of Subclinical Thyroid Dysfunction on Dementia/Mini-Mental State Examination (MMSE)
| Study, Year of Publication | Population, N | Women, % | Mean Age; sd, y | Followup Time, Months | Age, Min–Max, y | TSH Cutoff Level, mU/L | fT4 Measured | Thyroid Hormone Recipients Excluded? | |
|---|---|---|---|---|---|---|---|---|---|
| SHypo | SHyper | ||||||||
| Rotterdam (31), 2000c | 1843 | 61.9 | 68.8; 7.5 | 25.2 | 55–93 | >4.0 | <0.4 | Yes | Yes |
| Leiden 85-Plus Study (33), 2004 | 558 | 66.0 | 85.0; 0.0 | 44.4 | 85 | >4.8 | <0.3 | Yes | In SA |
| Rotterdam Scan (38), 2006 | 1077 | 51.2 | 72.3a; 7.4 | 66.0 | 60–90 | >4.3 | <0.4 | Yes | Yes |
| Health Ageing (36), 2008 | 1047 | 51.0 | 73.6; 6.2 | 24.0 | 64–94 | >4.8b | <0.3b | Yes | Yes |
| Framingham (34), 2008b | 1864 | 59.0 | 71.0; 7.0 | 152.4 | No | In SA | |||
| HAAS (30), 2009 | 665 | 0.0 | 78.0 | 56.4 | 71–93 | >4.3 | <0.4 | Yes | Yes |
| Japanese Study (35), 2010 | 229 | 65.0 | 80.9; 4.7 | 12.0 | >4.0 | NR | Yes | Yes | |
| Conselice (32), 2012c | 660 | 52.9 | 73.3; 6.0 | 45.6 | 65–91 | >4.5 | <0.45 | Yes | In SA |
| HIMS (29), 2012 | 3401 | 0.0 | 76.8; 3.5 | 70.8a | 70–89 | >4.0 | <0.4 | Yes | Yes |
| PROSPER (20), 2013 | 5154 | 49.4 | 75.0 | 38.4 | 80–82 | >4.5 | <0.45 | Yes | Yes |
| OCTABAIX (37), 2014d | 307 | 54.6 | 85.0; 0.0 | 36.0 | 85 | >5 | <0.25 | Yes | Yes |
Abbreviations: Conselice, Conselice Study of Brain Ageing; Framingham, The Framingham Study; HAAS, Honolulu-Asia Aging Study; Health Ageing, Health Ageing Study; HIMS, The Health in Men Study; Japanese Study, Cognitive function with SHypo in elderly people without dementia: One year follow up; Leiden 85+, Leiden 85-plus Study; MMSE, Mini-Mental State Examination; NR, not reported; OCTABAIX, OCTABAIX Study; PROSPER, The PROSPER Study; Rotterdam Scan, Rotterdam Scan Study; Rotterdam, The Rotterdam Study; SA, sensitivity analysis; SCTD, subclinical thyroid dysfunction.
Median.
The Framingham Study did not use TSH cut-offs for SCTD, but rather tertiles. Tertile 1: 0.1–1.08 mU/L for women, 0.10–0.90 mU/L for men; tertile 2: 1.10–2.03 mU/L for women, 0.99–1.80 mU/L for men; tertile 3: 2.10–9.90 mU/L for women, 1.09–9.90 mU/L for men. Therefore, this study could not be included in the meta-analysis but was added to a SA.
Due to additional unpublished data provided by the authors, the studies could be incorporated in the meta-analysis on SCTD and MMSE; unadjusted data.
Due to additional unpublished data provided by the authors, the study could be incorporated in the meta-analysis on SCTD and dementia.