Yougui Wu

Developmental and vascular risk factors for Alzheimer's disease

To investigate developmental and vascular risk factors for Alzheimers disease (AD), we examined 90 incident cases of probable AD in a cohort of 1859 individuals followed prospectively for six years. The presence of the APOE-epsilon4 allele was the strongest risk factor, and with increasing survival age, the effect of epsilon4 diminished. Among epsilon4 positives, developmental risk factors such as smaller head circumference (< or =54.4 cm) and having more than four children in the household at age 2-3 were independently associated with incident AD (hazard ratio (HR)=2.6 (95% CI 1.04-6.3) and 3.3 (1.2-9.2), respectively). Among epsilon4 negatives, vascular risk factors were related to AD risk (self-reported diagnoses of transient ischemic attack and diabetes (HR=5.1, 95% CI 1.7-15.5; HR 3.3, 95% CI 1.4-8.1)). These findings indicate that clinical AD is a result of early life as well as later life risk factors, and that genetic predisposition to the disease may modify the constellation of predictors.

Changes in Brain Volume and Cognition in a Randomized Trial of Exercise and Social Interaction in a Community-Based Sample of Non-Demented Chinese Elders

Physical exercise has been shown to increase brain volume and improve cognition in randomized trials of non-demented elderly. Although greater social engagement was found to reduce dementia risk in observational studies, randomized trials of social interventions have not been reported. A representative sample of 120 elderly from Shanghai, China was randomized to four groups (Tai Chi, Walking, Social Interaction, No Intervention) for 40 weeks. Two MRIs were obtained, one before the intervention period, the other after. A neuropsychological battery was administered at baseline, 20 weeks, and 40 weeks. Comparison of changes in brain volumes in intervention groups with the No Intervention group were assessed by t-tests. Time-intervention group interactions for neuropsychological measures were evaluated with repeated-measures mixed models. Compared to the No Intervention group, significant increases in brain volume were seen in the Tai Chi and Social Intervention groups (p < 0.05). Improvements also were observed in several neuropsychological measures in the Tai Chi group, including the Mattis Dementia Rating Scale score (p = 0.004), the Trailmaking Test A (p = 0.002) and B (p = 0.0002), the Auditory Verbal Learning Test (p = 0.009), and verbal fluency for animals (p = 0.01). The Social Interaction group showed improvement on some, but fewer neuropsychological indices. No differences were observed between the Walking and No Intervention groups. The findings differ from previous clinical trials in showing increases in brain volume and improvements in cognition with a largely non-aerobic exercise (Tai Chi). In addition, intellectual stimulation through social interaction was associated with increases in brain volume as well as with some cognitive improvements.

High Blood caffeine levels in MCI linked to lack of progression to dementia.

Although both human epidemiologic and animal model studies have suggested that caffeine/coffee protects against Alzheimers disease, direct human evidence for this premise has been lacking. In the present case-control study, two separate cohorts consisting of 124 total individuals (65-88 years old) were cognitively assessed and a blood sample taken for caffeine/biomarker analysis. Subjects were then monitored for cognitive status over the ensuing 2-4 year period to determine the extent to which initial plasma caffeine/biomarkers levels would be predictive of changes in cognitive status. Plasma caffeine levels at study onset were substantially lower (-51%) in mild cognitive impairment (MCI) subjects who later progressed to dementia (MCI→DEM) compared to levels in stable MCI subjects (MCI→MCI). Moreover, none of the MCI→DEM subjects had initial blood caffeine levels that were above a critical level of 1200 ng/ml, while half of stable MCI→MCI subjects had blood caffeine levels higher than that critical level. Thus, plasma caffeine levels greater than 1200 ng/ml (≈6 μM) in MCI subjects were associated with no conversion to dementia during the ensuing 2-4 year follow-up period. Among the 11 cytokines measured in plasma, three of them (GCSF, IL-10, and IL-6) were decreased in MCI→DEM subjects, but not in stable MCI→MCI subjects with high plasma caffeine levels. Coffee would appear to be the major or perhaps only source of caffeine for such stable MCI patients. This case-control study provides the first direct evidence that caffeine/coffee intake is associated with a reduced risk of dementia or delayed onset, particularly for those who already have MCI.

Pre-MCI and MCI: neuropsychological, clinical, and imaging features and progression rates.

OBJECTIVE To compare clinical, imaging, and neuropsychological characteristics and longitudinal course of subjects with pre-mild cognitive impairment (pre-MCI), who exhibit features of MCI on clinical examination but lack impairment on neuropsychological examination, to subjects with no cognitive impairment (NCI), nonamnestic MCI (naMCI), amnestic MCI (aMCI), and mild dementia. METHODS For 369 subjects, clinical dementia rating sum of boxes (CDR-SB), ApoE genotyping, cardiovascular risk factors, parkinsonism (UPDRS) scores, structural brain MRIs, and neuropsychological testing were obtained at baseline, whereas 275 of these subjects received an annual follow-up for 2-3 years. RESULTS At baseline, pre-MCI subjects showed impairment on tests of executive function and language, higher apathy scores, and lower left hippocampal volumes (HPCV) in comparison to NCI subjects. Pre-MCI subjects showed less impairment on at least one memory measure, CDR-SB and UPDRS scores, in comparison to naMCI, aMCI and mild dementia subjects. Follow-up over 2-3 years showed 28.6% of pre-MCI subjects, but less than 5% of NCI subjects progressed to MCI or dementia. Progression rates to dementia were equivalent between naMCI (22.2%) and aMCI (34.5%) groups, but greater than for the pre-MCI group (2.4%). Progression to dementia was best predicted by the CDR-SB, a list learning and executive function test. CONCLUSION This study demonstrates that clinically defined pre-MCI has cognitive, functional, motor, behavioral and imaging features that are intermediate between NCI and MCI states at baseline. Pre-MCI subjects showed accelerated rates of progression to MCI as compared to NCI subjects, but slower rates of progression to dementia than MCI subjects.

Cycad exposure and risk of dementia, MCI, and PDC in the Chamorro population of Guam

Objective: To study cycad-derived products as possible risk factors for dementia, mild cognitive impairment (MCI), and parkinsonism–dementia complex (PDC) on Guam. Methods: Complete risk factor data from in-person interviews of 166 cases of Guam dementia, 50 cases of amnestic MCI, and 21 cases of PDC were compared with 1,581 controls in the base population regarding exposure to cycad-derived products from a traditional food (fadang), consumption of fruit bats, and use of cycad-derived topical medicine. Results: Adjusted odds ratios (ORs) and 95% CIs for picking, processing, and eating fadang in young adulthood ranged from 1.42 (1.05 to 1.91) to 2.87 (1.48 to 5.56) and were consistently elevated and significant across all three diagnostic outcomes. Associations independent of exposure in young adulthood were for picking (OR 0.78, 95% CI 0.64 to 0.96) and processing (OR 0.77, 95% CI 0.63 to 0.94) fadang in childhood with Guam dementia. Men showed stronger and more consistent relations across exposure groups in young adulthood compared with women. No associations were found for consumption of fruit bats or exposure to cycad used as a topical medicine for any of the outcomes. Estimated adjusted population attributable risks suggest that exposure to eating fadang in young adulthood incurred the highest attributable risk percent. Conclusions: Environmental lifestyle and diet may contribute to the etiology of neurodegenerative diseases in the native population of Guam.

Severity of Medial Temporal Atrophy and Amnestic Mild Cognitive Impairment: Selecting Type and Number of Memory Tests

OBJECTIVE Medial temporal lobe atrophy (MTA) can be used as a biomarker of pathology that affects mechanisms of episodic memory. The authors compared the strength of this biomarker with performance on four memory measures and examined the influence of demographic factors including age, level of education, and primary language (English or Spanish). METHODS The Hopkins Verbal Learning Test-revised, Fuld Object Memory Evaluation (FOME), delayed memory for a story passage, and delayed visual reproduction of the Wechsler Memory Scale-revised tests were administered to 281 subjects who were diagnosed as having no cognitive impairment, mild cognitive impairment (MCI), impaired non-MCI, or dementia. MTA scores were obtained from visual ratings of the hippocampus, entorhinal cortex, and perirhinal cortex on coronal magnetic resonance imaging scans using a magnetization-prepared rapid gradient echo protocol. RESULTS Age was associated with scores on all memory measures and MTA. Level of educational attainment had no influence on FOME performance but had greater associations with scores on other memory measures. In regression models, FOME scores had the strongest relationship with MTA scores, accounting for 31% of the explained variability. Among subjects with MCI, an index representing the total number of memory tests that were impaired was also predictive of the severity of MTA scores. CONCLUSION Among four common tests of memory, the FOME was highly associated with MTA, and it exhibited minimal influences of education. Impairment on more than one memory test was more predictive of MTA than impairment on a single memory test.

Volumetric and visual rating of magnetic resonance imaging scans in the diagnosis of amnestic mild cognitive impairment and Alzheimer's disease

In the diagnosis of Alzheimers disease (AD), structural magnetic resonance imaging (MRI) scans have been used primarily to exclude non‐Alzheimers causes of dementia. However, the pattern and the extent of medial temporal atrophy on structural MRI scans, which correlate strongly with the pathological severity of AD, can be used to support the diagnosis of a degenerative dementia, especially AD, even in its early predementia stage.

Effects of Apolipoprotein E-ε4 and -ε2 in Amnestic Mild Cognitive Impairment and Dementia in Shanghai: SCOBHI-P

Objective: To determine apolipoprotein E (APOE)-ε4 and -ε2 frequencies and risk of mild cognitive impairment (MCI) and dementia in Shanghai, China. Methods: A total of 34 MCI and 34 dementia cases were recruited from an urban Memory Disorders Clinic and 32 controls were recruited from a residential community served by the clinic. Apolipoprotein E was genotyped using standard methods. Results: Among controls, frequencies were ε2, 0.11; ε3, 0.84; and ε4, 0.05; among MCI, 0.05, 0.77, and 0.18; and for dementia, 0.02, 0.84, and 0.15, respectively. In education-adjusted models, the odds ratio (OR) = 5.6 for dementia (95% CI = 1.09-29.3) and 4.7 for MCI (95% CI = 0.90-25.2) associated with any ε4 allele. The ε2 allele was inversely associated with dementia (OR = 0.12, 95% CI = 0.013-0.997) and MCI (OR = 0.38, 95% CI = 0.08-1.61). Conclusions: APOE-ε4 increases and -ε2 decreases the risk of dementia vs normal cognition. Similar trends were observed for amnestic mild cognitive impairment (aMCI).

High normal fasting blood glucose is associated with dementia in Chinese elderly

Diabetes is a risk factor for mild cognitive impairment (MCI) and dementia. However, the association between high normal fasting blood glucose (FBG) and dementia has not been studied.

Changes in Cognition During the Course of Eight Years in Elderly Japanese Americans: A Multistate Transition Model

PURPOSE To analyze cognitive changes in relation to mortality with the use of a multistate transition model. METHODS In a prospective cohort study of Japanese Americans living in King County, WA, study (n = 1985) cognitive states were defined as the errors in the Cognitive Abilities Screening Instrument score. Transition probabilities were modeled by the use of a modified Poisson distribution with the Poisson mean and mortality dependent on the cognitive state and covariates. RESULTS During an 8-year follow-up, 21.5% died (95% confidence interval [95% CI], 19.3-23.7), 26.6% experienced cognitive decline (95% CI, 24.2-29.1), and 51.9% remained stable or improved cognitively (95% CI, 49.2-54.6). In multivariable analyses, improvements were notably more likely to occur among younger, more-educated people and in women. Older age, male sex, and less education were each significantly related to mortality. CONCLUSIONS A multistate transition model can be used to estimate the impact of covariates on the individual probabilities of cognitive improvement, stability, decline, and death. This approach can have advantages for considering how interventions might work on patterns of cognitive change over time, especially if factors associated with the prevention of decline are also associated with risk of death.