Prevalence of thyroid dysfunction and its impact on cognition in older mexican adults: (SADEM study).

INTRODUCTION: Subclinical thyroid dysfunction is a possible risk factor for cognitive impairment in old age, but results are inconsistent. Aim of the present study was to evaluate the prevalence of thyroid dysfunction among older community-dwelling adults and to see whether thyroid function impacts the cognitive status of the elderly. METHODS: We included 1750 participants from the Study on Aging and Dementia in Mexico (SADEM). All subjects were evaluated clinically via specific interviews. TSH levels were analyzed by chemiluminescent immunometry assay. We classified participants into five thyroid state groups: (1) normal TSH levels (0.40-4.0 IU/L) were considered euthyroid; (2) Overt hyperthyroidism: TSH <0.3 IU/l and FT4 >23 pmol/l; (3) Overt hypothyroidism: TSH >4.8 IU/l, FT4 <13 pmol/l; (4) Subclinical hyperthyroidism: TSH <0.3 IU/l, FT4: 13-23 pmol/l; (5) Subclinical hypothyroidism: TSH >4.8 IU/l, FT4: 13-23 pmol/l. RESULTS: The overall estimated prevalence of thyroid dysfunction in Mexican population was 23.7% (95% CI, 22.66-26.77). Of these, 15.4% older adults were classified as subclinical hypothyroidism, 7.2% overt hypothyroidism, 0.5% subclinical hyperthyroidism, and 0.6% overt hyperthyroidism. The association of thyroid dysfunction with cognitive impairment was most evident in overt hypothyroidism OR = 1.261 (1.185-1.343). CONCLUSIONS: The present study demonstrated a high prevalence of thyroid dysfunction in Mexican elderly people living in the community. A relationship between cognitive impairment and the presence of hypothyroidism was also shown, and to a lesser degree in hyperthyroidism.

Influence of the placebo effect on oxidative stress in healthy older adults of Mexico City.

BACKGROUND: The placebo effect has been widely recognized in the randomized clinical trials; nevertheless, this effect has not been evaluated in terms of antioxidant therapy on oxidative stress (OxS). OBJECTIVE: The objective of this study was to determine the influence of the placebo effect on OxS in healthy older adults of Mexico City. METHODS: We carried out a double-blind controlled clinical assay with the participation of 75 healthy older adults residents for the past 10 years of Mexico City; randomly distributed into three groups of 25 subjects each after previous informed consent; control group not received any treatment, placebo group received a placebo with a pharmaceutical presentation similar to that of the treatment, whereas treatment group were administered 1000 mg of ascorbic acid and 400 IU of alpha-tocopherol. All subjects ingested the treatment daily according to study group for 12 months. We measured before and after 12 months of treatment, lipoperoxides levels (LPO), erythrocyte superoxide dismutase, glutathione peroxidase and total plasma antioxidant status with Randox Laboratories Ltd kits. The concentration of ascorbic acid and alpha-tocopherol were measured using high-performance liquid chromatography. RESULTS: The placebo group subjects showed a statistically significant decrease in LPO concentration, in the same way as the treatment group subjects (P < 0.01), both in comparison with a control group. CONCLUSION: Our findings suggest that the placebo has a significant effect on OxS.

Total antioxidant levels, gender, and age as risk factors for DNA damage in lymphocytes of the elderly.

During past years, the association of oxidative stress with DNA damage and its possible clinical translation into chronic degenerative illnesses, such as atherosclerosis, cancer, diabetes mellitus and Alzheimer's disease, has been demonstrated. In addition, it has been pointed out that age and gender are factors that influence the generation of DNA damage; however, this is still controversial. We have previously reported the results of a study of 88 subjects older than 60 years of age in whom DNA damage is related with serum levels of total antioxidants. The results of this study demonstrate a greater frequency of DNA damage in elderly persons with normal levels of antioxidants, in addition to males, and in the younger group of subjects, i.e., 60-69 years. In this work, we enlarged our study sample to 160 elderly subjects; in this way, we were able to evaluate the consistency of the influence of total antioxidants, age, and gender on the magnitude and grade of DNA damage in lymphocytes of the elderly. The results demonstrated that 45% of the subjects showed DNA damage, measured by an alkaline unicellular electrophoresis technique (comet assay). Similarly, 62% of the subjects presented low levels of total antioxidant levels measured by a colorimetric method (Randox Kit). A greater percentage of DNA damage was observed in subjects with normal levels of antioxidants (48%) compared with subjects with low levels (43%), although the difference was not statistically significant. The group of subjects 70 years of age or older showed a greater percentage of DNA damage (50%) than the group of subjects of 60-69 years of age (41%). However, the difference was again not statistically significant (P>0.05). With respect to gender, 64% of males and 38% of females had DNA damage with an odds ratio (OR) of 2.86 and a 95% confidence interval (CI) of 1.31-6.32 (P<0.05). In the logistic regression analysis, the interaction of the male sex variables with low antioxidants had an OR of 2.5 (CI 95%, 1.33-4.68; P<0.01). We conclude that the interaction of male sex factors-low levels of antioxidants would justify the indication of antioxidant dietetic supplements.

Serum leptin levels and blood pressure in the overweight elderly.

BACKGROUND: Leptin is a protein produced by adipocytes that reduces reflex appetite by blocking the Y neuropeptide, thus causing body weight loss. A large percentage of elderly people are reported to exhibit obesity, which may be caused by low leptin serum levels. However, hypertension is a highly prevalent condition in old age. Obesity under these circumstances is an added risk factor due to the presence and severity of hypertension and thus can be related with leptin serum levels. Our objective was to determine the relationship between leptin serum levels and hypertension in obese elderly persons. METHODS: A comparative transverse study was done in a random sample of 61 elderly persons-36 obese and 25 non-obese. Their blood pressure and their leptin serum levels by RIA were measured. RESULTS: Leptin serum levels showed a statistically significant difference (p <0.05) in elderly obese individuals (12.8 +/- 4.4 microg/L vs. 9.8 +/- 4.2 microg/L). Likewise, 45% of obese elderly individuals and 20% of the non-obese were hypertensive with a predominant elevation of the systolic pressure. CONCLUSIONS: The higher serum leptin levels in obese elderly individuals suggests that aging is associated with resistance to leptin and/or to a decrease of receptors for this hormone. The high incidence of hypertension during the aging process is the result of associated obesity (OR = 3.2, CI 0.88-13.14).

DNA damage in lymphocytes of elderly patients in relation with total antioxidant levels.

DNA damage may occur as a result of an imbalance between the production and removal of free radicals, a process in which age plays an outstanding role. The purpose of this study was to analyze the relationship between total antioxidants and DNA damage in a sample of old age people in Mexico City. The sample included a total of 88 subjects, 15 males and 69 females, with a mean age of 65.5 years old (range between 60 and 79 years old), all of whom had lived in Mexico City during the last 10 years and had been diagnosed as clinically healthy. Results showed that 52% of the subjects presented DNA damage in peripheral blood lymphocytes which was assessed through an alkaline unicellular electrophoresis procedure (Comet Test), regardless of total antioxidant serum levels quantified through a colorimetric method (Randox Kit). Higher non-damage occurrences were observed in subjects with low antioxidant levels, a difference that was statistically significant (P < 0.05). Furthermore, the highest incidence of damaged cells was observed in subjects belonging to the 70-years-old-and-above group (P < 0.05). As to the magnitude and intensity of the damage associated to total antioxidant concentrations, a trend toward greater DNA damage in subjects with low serum levels was observed. It is concluded that low antioxidant levels are not always indicative of oxidative strain and therefore should not be considered as predictors of DNA damage in this population.