Stephen T. Chen

Constraints on E-commerce in Less Developed Countries: The Case of China

We suggest a revised framework based on Michael Porters Diamond of National Competitive Advantage that can be applied in examining development of e-commerce in less-developed countries. This incorporates cross-industry institutions and networks as key determinants of national competitive advantage. Using this framework we show that China has made significant progress in building the technical infrastructure and regulatory framework for e-commerce. However, it suffers still from poorly developed institutions and social networks. These are crucial in moving into the second phase of development of electronic commerce where the technologies are integrated into existing industries.

Modifiable Risk Factors for Alzheimer Disease and Subjective Memory Impairment across Age Groups

Introduction Previous research has identified modifiable risk factors for Alzheimers disease (AD) in older adults. Research is limited on the potential link between these risk factors and subjective memory impairment (SMI), which may precede AD and other dementias. Examination of these potential relationships may help identify those at risk for AD at a stage when interventions may delay or prevent further memory problems. The objective of this study was to determine whether risk factors for AD are associated with SMI among different age groups. Method Trained interviewers conducted daily telephone surveys (Gallup-Healthways) of a representative community sample of 18,614 U.S. respondents, including 4,425 younger (age 18 to 39 years), 6,365 middle-aged (40 to 59 years), and 7,824 older (60 to 99 years) adults. The surveyors collected data on demographics, lifestyles, and medical information. Less education, smoking, hypertension, diabetes, less exercise, obesity and depression, and interactions among them, were examined for associations with SMI. Weighted logistic regressions and chi-square tests were used to calculate odds ratios and confidence intervals for SMI with each risk factor and pairwise interactions across age groups. Results Depression, less education, less exercise, and hypertension were significantly associated with SMI in all three age groups. Several interactions between risk factors were significant in younger and middle-aged adults and influenced their associations with SMI. Frequency of SMI increased with age and number of risk factors. Odds of having SMI increased significantly with just having one risk factor. Conclusions These results indicate that modifiable risk factors for AD are also associated with SMI, suggesting that these relationships occur in a broad range of ages and may be targeted to mitigate further memory problems. Whether modifying these risk factors reduces SMI and the eventual incidence of AD and other dementias later in life remains to be determined.

Bipolar Disorder in Late Life: A Review

Although there is a broad base of literature on depression among elderly patients and on mania in younger patients, there is a relative paucity of information on bipolar disorder in the elderly population. While the quantities of data reflect the relative prevalences of these illnesses, there is evidence to suggest that classification of mania in the elderly with respect to age of onset, natural course, family history, and pathophysiology may be useful in understanding the heterogeneous etiologies of this syndrome. This paper presents a review of the literature on the incidence and course of illness in late-life bipolar disorder. Further, dilemmas of diagnostic classification in relation to associated risk factors will be discussed.

Healthy behavior and memory self-reports in young, middle-aged, and older adults.

BACKGROUND Previous research has shown that healthy behaviors, such as regular physical exercise, a nutritious diet, and not smoking, are associated with a lower risk for Alzheimers disease and dementia. However, less is known about the potential link between healthy behaviors and mild memory symptoms that may precede dementia in different age groups. METHODS A daily telephone survey (Gallup-Healthways Well-Being Index) of US residents yielded a random sample of 18,552 respondents ranging in age from 18 to 99 years, including 4,423 younger (age 18-39 years), 6,356 middle-aged (40-59 years), and 7,773 older (60-99 years) adults. The questionnaire included demographic information and the Healthy Behavior Index (questions on smoking, eating habits, and frequency of exercise). General linear models and logistic regressions were used in the analysis. RESULTS Older adults were more likely to report healthy behaviors than were middle-aged and younger adults. Reports of memory problems increased with age (14% of younger, 22% of middle-aged, and 26% of older adults) and were inversely related to the Healthy Behavior Index. Reports of healthy eating were associated with better memory self-reports regardless of age, while not smoking was associated with better memory reports in the younger and middle-aged and reported regular exercise with better memory in the middle-aged and older groups. CONCLUSIONS These findings indicate a relationship between reports of healthy behaviors and better self-perceived memory abilities throughout adult life, suggesting that lifestyle behavior habits may protect brain health and possibly delay the onset of memory symptoms as people age.

Memory and Brain Amyloid and Tau Effects of a Bioavailable Form of Curcumin in Non-Demented Adults: A Double-Blind, Placebo-Controlled 18-Month Trial

OBJECTIVE Because curcumins anti-inflammatory properties may protect the brain from neurodegeneration, we studied its effect on memory in non-demented adults and explored its impact on brain amyloid and tau accumulation using 2-(1-{6-[(2-[F-18]fluoroethyl)(methyl)amino]-2-naphthyl}ethylidene)malononitrile positron emission tomography (FDDNP-PET). METHODS Forty subjects (age 51-84 years) were randomized to a bioavailable form of curcumin (Theracurmin® containing 90 mg of curcumin twice daily [N = 21]) or placebo (N = 19) for 18 months. Primary outcomes were verbal (Buschke Selective Reminding Test [SRT]) and visual (Brief Visual Memory Test-Revised [BVMT-R]) memory, and attention (Trail Making A) was a secondary outcome. FDDNP-PET signals (15 curcumin, 15 placebo) were determined in amygdala, hypothalamus, medial and lateral temporal, posterior cingulate, parietal, frontal, and motor (reference) regions. Mixed effects general linear models controlling for age and education, and effect sizes (ES; Cohens d) were estimated. RESULTS SRT Consistent Long-Term Retrieval improved with curcumin (ES = 0.63, p = 0.002) but not with placebo (ES = 0.06, p = 0.8; between-group: ES = 0.68, p = 0.05). Curcumin also improved SRT Total (ES = 0.53, p = 0.002), visual memory (BVMT-R Recall: ES = 0.50, p = 0.01; BVMT-R Delay: ES = 0.51, p = 0.006), and attention (ES = 0.96, p < 0.0001) compared with placebo (ES = 0.28, p = 0.1; between-group: ES = 0.67, p = 0.04). FDDNP binding decreased significantly in the amygdala with curcumin (ES = -0.41, p = 0.04) compared with placebo (ES = 0.08, p = 0.6; between-group: ES = 0.48, p = 0.07). In the hypothalamus, FDDNP binding did not change with curcumin (ES = -0.30, p = 0.2), but increased with placebo (ES = 0.26, p = 0.05; between-group: ES = 0.55, p = 0.02). CONCLUSIONS Daily oral Theracurmin may lead to improved memory and attention in non-demented adults. The FDDNP-PET findings suggest that symptom benefits are associated with decreases in amyloid and tau accumulation in brain regions modulating mood and memory.

FDDNP-PET Tau brain protein binding patterns in military personnel with suspected chronic traumatic encephalopathy

BACKGROUND Our group has shown that in vivo tau brain binding patterns from FDDNP-PET scans in retired professional football players with suspected chronic traumatic encephalopathy differ from those of tau and amyloid aggregate binding observed in Alzheimers disease (AD) patients and cognitively-intact controls. OBJECTIVE To compare these findings with those from military personnel with histories of mild traumatic brain injury(mTBI). METHODS FDDNP-PET brain scans were compared among 7 military personnel and 15 retired players with mTBI histories and cognitive and/or mood symptoms, 24 AD patients, and 28 cognitively-intact controls. Nonparametric ANCOVAs with Tukey-Kramer adjusted post-hoc comparisons were used to test for significant differences in regional FDDNP binding among subject groups. RESULTS FDDNP brain binding was higher in military personnel compared to controls in the amygdala, midbrain, thalamus, pons, frontal and anterior and posterior cingulate regions (p < 0.01-0.0001). Binding patterns in the military personnel were similar to those of the players except for the amygdala and striatum (binding higher in players; p = 0.02-0.003). Compared with the AD group, the military personnel showed higher binding in the midbrain (p = 0.0008) and pons (p = 0.002) and lower binding in the medial temporal, lateral temporal, and parietal regions (all p = 0.02). CONCLUSION This first study of in vivo tau and amyloid brain signals in military personnel with histories of mTBI shows binding patterns similar to those of retired football players and distinct from the binding patterns in AD and normal aging, suggesting the potential value of FDDNP-PET for early detection and treatment monitoring in varied at-risk populations.