Department of Gerontology and Geriatrics, Leiden University Medical Center, Leiden, The Netherlands.
PLoS One. 2013;8(3):e59199. doi: 10.1371/journal.pone.0059199. Epub 2013 Mar 12.
Subclinical thyroid dysfunction has been implicated as a risk factor for cognitive decline in old age, but results are inconsistent. We investigated the association between subclinical thyroid dysfunction and cognitive decline in the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER).
Prospective longitudinal study of men and women aged 70-82 years with pre-existing vascular disease or more than one risk factor to develop this condition (N = 5,154). Participants taking antithyroid medications, thyroid hormone supplementation and/or amiodarone were excluded. Thyroid function was measured at baseline: subclinical hyper- and hypothyroidism were defined as thyroid stimulating hormones (TSH) <0.45 mU/L or >4.50 mU/L respectively, with normal levels of free thyroxine (FT4). Cognitive performance was tested at baseline and at four subsequent time points during a mean follow-up of 3 years, using five neuropsychological performance tests.
Subclinical hyperthyroidism and hypothyroidism were found in 65 and 161 participants, respectively. We found no consistent association of subclinical hyper- or hypothyroidism with altered cognitive performance compared to euthyroid participants on the individual cognitive tests. Similarly, there was no association with rate of cognitive decline during follow-up.
We found no consistent evidence that subclinical hyper- or hypothyroidism contribute to cognitive impairment or decline in old age. Although our data are not in support of treatment of subclinical thyroid dysfunction to prevent cognitive dysfunction in later life, only large randomized controlled trials can provide definitive evidence.
亚临床甲状腺功能障碍被认为是老年认知能力下降的一个危险因素，但结果并不一致。我们在 PROspective Study of Pravastatin in the Elderly at Risk（PROSPER）中研究了亚临床甲状腺功能障碍与认知能力下降之间的关系。
这是一项对年龄在 70-82 岁、有既往血管疾病或多种发生该疾病风险因素的男性和女性进行的前瞻性纵向研究（n=5154）。排除服用抗甲状腺药物、甲状腺激素补充剂和/或胺碘酮的患者。在基线时测量甲状腺功能：亚临床甲状腺功能亢进症和甲状腺功能减退症分别定义为促甲状腺激素（TSH）<0.45mU/L 或>4.50mU/L，游离甲状腺素（FT4）水平正常。在平均 3 年的随访期间，使用 5 项神经心理学测试，在基线和随后的 4 个时间点测试认知表现。
分别有 65 名和 161 名参与者出现亚临床甲状腺功能亢进症和甲状腺功能减退症。与甲状腺功能正常的参与者相比，我们没有发现亚临床甲状腺功能亢进症或甲状腺功能减退症与单个认知测试中认知表现改变之间存在一致的关联。同样，在随访期间，也没有与认知能力下降的速度有关联。
我们没有发现一致的证据表明亚临床甲状腺功能亢进症或甲状腺功能减退症导致老年认知障碍或下降。虽然我们的数据不支持治疗亚临床甲状腺功能障碍以预防晚年的认知功能障碍，但只有大型随机对照试验才能提供明确的证据。
