The Association Between Subclinical Hypothyroidism And Cognitive Impairment

[Background]Thyroid hormone plays an important role on the occurrence,development and the maintenance of normal function of central nervous system(CNS).While the association between overt hypothyroidism and cognitive impairment is well established,the association between subclinical hypothyroidism(SCH)and cognitive impairment has not been completely elucidated.[Objective]1.To observe the characteristics of cognitive impairment in patients with subclinical hypothyroidism.2.To explore the correlation between serum thyroid stimulating hormone (TSH)and cognitive function.[Methods]Select 50 cases with subclinical hypothyroidism who visited in the Endocrinology outpatient clinic of Fujian Medical University Affiliated Union Hospital from March 2016 to June 2016,24 cases of men and 26 cases of women,the average age 40-73(54.7±10.2)years old,the average education years 0-15(7.5±4.7).50 healthy subjects were randomly selected as the healthy control group at 1:1 ratio.24 cases of men and 26 cases of women,the average age 40-79(55.0±10.5),the average education years 0-16(7.9±4.0).Collecting data of each research object:weight,height,systolic blood pressure(SBP),diastolic blood pressure(DBP),smoking history,body mass index(BMI,BMI=body weight(kg)/height~2(m~2));Some hematological parameters,such as thyroid stimulating hormone(TSH),free thyroid hormones and antibodies,fasting blood glucose(FBG),triglyceride(TG),total cholesterol(TC),high-density lipoprotein cholesterol(HDL-C),low-density lipoprotein cholesterol(LDL-C),oral glucose tolerance test(OGTT-2h),blood uric acid.Cognitive functions were assessed by using Addenbrooke cognitive examination-revised(ACE-R)and activities of daily living(ADL).Statistical analysis was performed using SPSS19.0 statistical software,independent sample t test was used for continuous variables,?~2 test for categorical variables,differences and correlation among the indexes were using linear correlation analysis,partial correlation and multiple regression analysis.Tests were considered significant if P values were less than 0.05.[Result]1.The total scores of ACE-R,attention/orietation,memory between the patients and controls had statistical significance(P<0.05);the semantic verbal fluency,language,visuospatial abilities and total scores of ADL between the two groups had no statistical significance(P>0.05).2.The correlation analysis demonstrated:(1)age and the total scores of ACE-R were negatively correlated;educational status and the total scores of ACE-R were positively correlated(P<0.05);(2)serum TSH level and the total scores of ACE-R,attention/orientation,memory,language were negatively correlated(P<0.05);(3)serum free T4 and the total scores of ACE-R,attention/orientation,memory,semantic verbal fluency,language were positively correlated(P<0.05).3.The multiple linear stepwise regression analysis demonstrated:the influence of educational status on the total scores of ACE-R,attention/directional,memory,semantic verbal fluency,language and visuospatial abilities had statistical significance(P<0.05);the influence of serum free T4 on the total scores of ACE-R,memory had statistical significance(P<0.05);the influence of age,serum TSH level on cognitive function has no statistical significance(P>0.05).[Conclusion]Patients with subclinical hypothyroidism have some cognitive deficits in attention/orientation and memory.Serum free T4 level and ACE-R scores,memory were positively correlated.Cognitive function is influenced by education level.