Biomedical subjects

Jae H Kang

Publications and source records attributed to Jae H Kang.

7 recordsLinked to original sources

PubMed2006

Midlife plasma insulin-like growth factor I and cognitive function in older men.

CONTEXT: Emerging biological and epidemiological evidence suggests possible benefits of higher IGF-I levels in cognitive aging. OBJECTIVE: The objective of the study was to examine the relation of midlife plasma IGF-I levels to late-life cognition. DESIGN, SETTING, AND PARTICIPANTS: We conducted a secondary analysis from the Physicians' Health Study II, a prospective cohort of U.S. male physicians. Participants provided blood samples from 1982 to 1984 (mean age 57 yr). Using stored samples, we measured free IGF-I in 376 men and total IGF-I and IGF binding protein-3 in 460 men. Starting in 2001, we administered telephone-based tests of general cognition [the Telephone Interview of Cognitive Status (TICS)], verbal memory, and category fluency. We estimated multivariable-adjusted mean differences in cognitive performance across levels of free IGF-I and IGF-I to IGF binding protein-3 molar ratio. MAIN OUTCOME MEASURES: Global score (averaging performance across all individual cognitive tests), the TICS, and a verbal memory score were measured. RESULTS: Each sd increment in free IGF-I was associated with a multivariable-adjusted increase of 0.08 U (P = 0.02) on the global score. This mean difference was equivalent to that observed between men 2 yr apart in age: i.e. each sd increase in free IGF-I appeared cognitively equivalent to staying 2 yr younger. No significant mean differences in TICS scores were observed across free IGF-I levels. For verbal memory, each sd increment in free IGF-I was associated with an adjusted mean difference of 0.08 U (P = 0.03). Results appeared consistent for the molar ratio but were not statistically significant. CONCLUSION: Higher midlife free IGF-I may be associated with better late-life cognition.

Adult↗

PubMed2006

Plasma C-peptide and cognitive performance in older men without diabetes.

BACKGROUND: Emerging evidence suggests that type 2 diabetes may be related to diminished cognition, but little data are available directly regarding the role of insulin levels. OBJECTIVE: The objective of this prospective cohort study was to examine the relation of insulin secretion to cognitive function among men without diabetes. SETTING: The study setting was the Physicians' Health Study-U.S. male physicians. PARTICIPANTS: Three hundred sixty-seven men who provided blood samples in 1982, when they had no lifetime history of diabetes and ranged in age from 47-65 years (mean age: 57 years). MEASUREMENTS: The authors assayed plasma C-peptide, reflecting insulin secretion, in the stored blood samples. Beginning in 2001, an average 18 years after blood collection, the authors administered telephone interviews, including tests of general cognition (Telephone Interview of Cognitive Status [TICS]), verbal memory, and category fluency. The authors used regression models to estimate mean differences in cognitive performance across levels of C-peptide controlling for a wide variety of potential confounding factors. RESULTS: On the TICS, men in the top tertile of C-peptide performed significantly worse than those in the bottom (multivariable-adjusted mean difference: -1.01 points, 95% confidence interval: -1.78 to -0.24); this apparent impact of C-peptide on cognition was equivalent to the cognitive differences the authors observed between men 6 years apart in age. Performance on the global score (combining results from all the individual tests) and verbal memory score (combining results from four tests of verbal memory) appeared lower among men in the highest C-peptide tertile, but results were not statistically significant. CONCLUSION: Higher midlife insulin secretion may be related to decreased later-life cognitive function, even among men without diabetes.

C-Peptide↗

PubMed2005

Fruit and vegetable consumption and cognitive decline in aging women.

We prospectively examined fruit and vegetable intake in relation to cognitive function and decline among aging women. Participants were followed from in 1976 with biennial questionnaires, and food frequency questionnaires were administered in 1984, 1986, and every 4 years thereafter. From 1995 to 2001, we administered, by telephone, six cognitive tests measuring general cognition, verbal memory, category fluency, and working memory. We repeated assessments two years later for 13,388 women (>90% follow-up). We averaged dietary intakes from 1984 through the first cognitive assessment, and used linear regression to obtain multivariable-adjusted mean differences in performance and decline in performance across intake levels. Fruits were not associated with cognition or cognitive decline. However, total vegetable intake was significantly associated with less decline. Specifically, on a global score combining all tests, women in the highest quintile of cruciferous vegetables declined slower (by 0.04 unit; 95% confidence interval, 0.003, 0.07; p trend = 0.1) compared with the lowest quintile. Women consuming the most green leafy vegetables also experienced slower decline than women consuming the least amount (by 0.05 unit; 95% confidence interval, 0.02, 0.09; p trend < 0.001). These mean differences were equivalent to those observed for women about 1 to 2 years apart in age.

Adult↗

PubMed2004

Postmenopausal hormone therapy and risk of cognitive decline in community-dwelling aging women.

BACKGROUND: A randomized trial of postmenopausal women over age 65 reported increased risks of cognitive decline with 4 years of combined estrogen and progestin treatment. However, questions remain, including the effect of longer duration or of hormone therapy initiated at younger ages. METHODS: The Nurses' Health Study is a prospective cohort begun in 1976, comprising 121,700 female nurses who report health information via biennial mailed questionnaires. This substudy includes 13,807 participants age 70 to 81 who completed two telephone cognitive assessments, 2 years apart, between 1995 and 2003. General cognition, verbal memory, category fluency, and attention were tested. Multiple linear regression was used to estimate adjusted mean declines and logistic regression to estimate adjusted risks of substantial decline in cognition (> or =2 SD of baseline performance) across hormone groups. APOE genotype was available in a subset of 3,667 participants. RESULTS: Overall, little difference was found in mean cognitive decline between current hormone users and never users. However, for long-term users of estrogen alone or combined with progestin, increased risk of substantial decline was observed on most cognitive tests (relative risk [RR] = 1.25 to 1.72). Decline was particularly high among women initiating hormones at older ages compared with never users: for example, on our test of general cognition, RR of substantial decline was 1.74 (95% CI 1.08, 2.81) and mean difference in decline was -0.43 (95% CI -0.73, -0.12). No significant interactions between hormone use and APOE epsilon4 allele were observed. CONCLUSION: Postmenopausal hormone therapy provides no appreciable cognitive benefits in older women.

Age Factors↗

PubMed2004

Dietary fat consumption and primary open-angle glaucoma.

BACKGROUND: Prostaglandin F(2alpha) analogues are effective intraocular-pressure-lowering drugs. Dietary fatty acids affect endogenous prostaglandin F(2alpha) concentrations and may thus influence intraocular pressure. OBJECTIVE: We prospectively examined dietary fat consumption in relation to primary open-angle glaucoma (POAG). DESIGN: Women (n = 76 199 in the Nurses' Health Study) and men (n = 40 306 in the Health Professionals Follow-Up Study) free of POAG in 1980 and 1986, respectively, were followed until 1996 if they were > or =40 y old and reported receiving eye exams during follow-up. Potential confounders were assessed on biennial questionnaires, and energy-adjusted cumulative averaged fat intakes were measured by using validated food-frequency questionnaires. We analyzed 474 self-reported POAG cases confirmed by medical chart review. Cohort-specific multivariate rate ratios (RRs) were obtained by using proportional hazards models and were then pooled. RESULTS: Major fats and fat subtypes were not independently associated with POAG risk. Pooled multivariate RRs (95% CI) for POAG comparing the highest with the lowest quintile of fat intake were as follows: 0.90 (0.67, 1.21) for total fat, 1.03 (0.77, 1.38) for saturated fat, 0.76 (0.56, 1.03) for monounsaturated fat, and 0.87 (0.66, 1.16) for polyunsaturated fat, none of which were statistically significant. We found a suggestive positive association between a higher ratio of n-3 to n-6 polyunsaturated fat and risk of POAG [RR = 1.49 (1.11, 2.01); P for trend = 0.10], which was stronger for high-tension POAG [RR = 1.68 (1.18, 2.39); P for trend = 0.009]. CONCLUSION: A high ratio of n-3 to n-6 polyunsaturated fat appears to increase the risk of POAG, particularly high-tension POAG. Further studies are needed.

Adult↗

PubMed2003

Antioxidant intake and primary open-angle glaucoma: a prospective study.

The relation between dietary antioxidant intake and primary open-angle glaucoma risk was examined in participants aged over 40 years in the Nurses' Health Study (n = 76,200) and the Health Professionals Follow-up Study (n = 40,284). They were followed biennially from 1980 and 1986, respectively, to 1996, during periods when they received an eye examination. Dietary intakes were measured repeatedly from 1980 in the Nurses' Health Study and from 1986 in the Health Professionals Follow-up Study using validated food frequency questionnaires. The authors analyzed 474 self-reported glaucoma cases confirmed by medical chart review to have primary open-angle glaucoma with visual field loss. The authors used Cox proportional hazards models for cohort-specific multivariate analyses, and results were pooled using random effects models. The pooled multivariate rate ratios for primary open-angle glaucoma comparing the highest versus lowest quintile of cumulative updated intake were 1.17 (95% confidence interval (CI): 0.87, 1.58) for alpha-carotene, 1.10 (95% CI: 0.82, 1.48) for beta-carotene, 0.95 (95% CI: 0.70, 1.29) for beta-cryptoxanthin, 0.82 (95% CI: 0.60, 1.12) for lycopene, 0.92 (95% CI: 0.69, 1.24) for lutein/zeaxanthin, 1.05 (95% CI: 0.59, 1.89) for vitamin C, 0.97 (95% CI: 0.62, 1.52) for vitamin E, and 1.11 (95% CI: 0.82, 1.51) for vitamin A. In conclusion, the authors did not observe any strong associations between antioxidant consumption and the risk of primary open-angle glaucoma.

Adult↗

PubMed2003

Prospective study of cigarette smoking and the risk of primary open-angle glaucoma.

OBJECTIVE: To examine the association between cigarette smoking and incident primary open-angle glaucoma (POAG). METHODS: Female nurses and male health professionals were prospectively followed up from 1980 and 1986, respectively, to 1996. Participants were at least 40 years old, were free of diagnosed glaucoma at baseline, and reported being examined by an ophthalmologist or optometrist during follow-up. Smoking history and other POAG risk factors were updated with biennial questionnaires. A total of 450 incident cases of POAG were identified. Both cohort-specific proportional hazards analyses and analyses pooled across cohorts were conducted. RESULTS: After controlling for potential risk factors of POAG, including age, hypertension, and African American heritage, neither current smokers (relative risk, 0.85; 95% confidence interval, 0.62-1.18) nor past smokers (relative risk, 0.91; 95% confidence interval, 0.63-1.32) were at greater risk for POAG than those who had never smoked. Heavier smoking did not increase the risk of POAG. A modest inverse association was observed with pack-years of smoking: those with 30 or more pack-years had a 22% reduced risk of POAG (relative risk, 0.78; 95% confidence interval, 0.55-1.11; P for linear trend,.06) than those who had never smoked. CONCLUSION: Cigarette smoking is not an important risk factor for POAG.

Adult↗