Association of interleukin-1 gene polymorphisms with dementia in a community-based sample: The Honolulu-Asia Aging Study

The interleukin-1 (IL-1) pro-inflammatory cytokine family participates in inflammatory processes and vessel damage involved in neurodegeneration. Recent studies suggest that Alzheimer's disease (AD) and vascular dementia (VaD) may share genetic risk factors. In this study, the frequency of polymorphisms in the genes coding for interleukin (IL)-1alpha, IL-1beta and the IL-1 receptor antagonist (RN) and their genotype associations with late-onset AD and VaD were determined in a Japanese-American cohort of men (n=931) participating in the Honolulu-Asia Aging Study (HAAS). A significant association was found between the IL-1beta (-511) and IL-1RN (+2018) polymorphisms and AD, suggesting that these variants confer an increased risk. Possessing the IL-1beta (-511) T/T genotype was also associated with VaD. There was no difference in the IL-1beta (+3953) frequency among the groups. Our results support the hypothesis that certain genetic variations contained within the IL-1 gene family contribute to the pathogenesis of dementia.

Analysis and validation of automated skull stripping tools: a validation study based on 296 MR images from the Honolulu Asia aging study

As population-based epidemiologic studies may acquire images from thousands of subjects, automated image post-processing is needed. However, error in these methods may be biased and related to subject characteristics relevant to the research question. Here, we compare two automated methods of brain extraction against manually segmented images and evaluate whether method accuracy is associated with subject demographic and health characteristics. MRI data (n = 296) are from the Honolulu Asia Aging Study, a population-based study of elderly Japanese-American men. The intracranial space was manually outlined on the axial proton density sequence by a single operator. The brain was extracted automatically using BET (Brain Extraction Tool) and BSE (Brain Surface Extractor) on axial proton density images. Total intracranial volume was calculated for the manually segmented images (ticvM), the BET segmented images (ticvBET) and the BSE segmented images (ticvBSE). Mean ticvBSE was closer to that of ticvM, but ticvBET was more highly correlated with ticvM than ticvBSE. BSE had significant over (positive error) and underestimated (negative error) ticv, but net error was relatively low. BET had large positive and very low negative error. Method accuracy, measured in percent positive and negative error, varied slightly with age, head circumference, presence of the apolipoprotein eepsilon4 polymorphism, subcortical and cortical infracts and enlarged ventricles. This epidemiologic approach to the assessment of potential bias in image post-processing tasks shows both skull-stripping programs performed well in this large image dataset when compared to manually segmented images. Although method accuracy was statistically associated with some subject characteristics, the extent of the misclassification (in terms of percent of brain volume) was small.

Midlife Pulse Pressure and Incidence of Dementia

Background and Purpose— Previous studies have shown that midlife systolic blood pressure (SBP) predicts late-life cognitive decline and incident dementia. This study explores whether this association is attributable to the pulsatile, ie, pulse pressure (PP), or the nonpulsatile component of blood pressure (BP).

Methods— Data are from the Honolulu-Asia Aging Study, a community-based study of Japanese American men. Midlife BP was measured in 1971 to 1974 and dementia assessment was conducted in late-life. The 2505 men who were dementia free in 1991 and had complete follow-up data were re-examined for incident dementia in 1994 to 1996 and 1997 to 1999. Their age ranged from 71 to 93 years. Survival analysis with age as the time scale was performed to estimate the risk (hazard ratio [HR] and 95% CI) for incident dementia associated with mid- and late-life tertiles of PP and mean arterial BP, as well as SBP and diastolic BP categories.

Results— Over a mean of 5.1 years of follow-up, 189 cases (7.5%) of incident Alzheimer disease or vascular dementia were identified. After adjustment for cerebrovascular risk factors, dementia was significantly associated with SBP (HR 1.77; 95% CI, 1.10 to 2.84, for SBP ≥140 mm Hg compared with SBP <120 mm Hg), but not with PP tertiles. Limiting the analysis to those never treated with antihypertensives, high levels of all 4 BP components were significantly associated with dementia. In models with 2 BP components, only SBP remained significant in both the total sample and the never-treated subgroup (HR 2.29; 95% CI, 1.23 to 4.25, for SBP ≥140 mm Hg in total sample), whereas PP was not significantly associated with the risk for dementia.

Conclusions— Midlife PP is not independently associated with dementia incidence. Midlife SBP is the strongest BP component predicting incident dementia.

Excessive daytime sleepiness and subsequent development of Parkinson disease

OBJECTIVE

To determine if excessive daytime sleepiness (EDS) can predate future Parkinson disease (PD).

METHODS

EDS was assessed in 3,078 men aged 71 to 93 years in the Honolulu-Asia Aging Study from 1991 to 1993. All were free of prevalent PD and dementia. Follow-up for incident PD was based on three repeat neurologic assessments from 1994 to 2001.

RESULTS

During the course of follow-up, 43 men developed PD (19.9/10,000 person-years). After age adjustment, there was more than a threefold excess in the risk of PD in men with EDS vs men without EDS (55.3 vs 17.0/10,000 person-years; odds ratio [OR] = 3.3; 95% CI = 1.4 to 7.0; p = 0.004). Additional adjustment for insomnia, cognitive function, depressed mood, midlife cigarette smoking and coffee drinking, and other factors failed to alter the association between EDS and PD (OR = 2.8; 95% CI = 1.1 to 6.4; p = 0.014). Other sleep related features such as insomnia, daytime napping, early morning grogginess, and frequent nocturnal awakening showed little relation with the risk of PD.

CONCLUSIONS

Excessive daytime sleepiness may be associated with an increased risk of developing Parkinson disease.

Memory complaints in nondemented men predict future pathologic diagnosis of Alzheimer disease

The validity of memory complaints as a predictor of Alzheimer disease (AD) was assessed in 237 Japanese-American men autopsied at ages 74 to 97 years. These men were free of dementia at the time memory complaints were assessed 1 to 11 years earlier. Memory complaints were found to predict the neuropathologic diagnosis of AD after adjusting for age, time to death, education, depression, and cognitive functioning.

Associations of cortical astrogliosis with cognitive performance and dementia status

We examined 204 decedents of the autopsy component of the Honolulu-Asia Aging Study, a longitudinal cohort study, who had been clinically assessed for dementia. A sensitive ELISA technique was used to quantify glial fibrillary acidic protein (GFAP), a marker for astrogliosis, in four specific cortical brain regions and assess associations between GFAP and 1) a measure of cognitive function, 2) several clinical dementia conditions, and 3) neuritic plaque (NP) and neurofibrillary tangle (NFT) formation. Cognitive function was inversely associated with GFAP in the occipital, parietal and temporal lobes, but not in the frontal lobe. This relationship remained significant when the contribution of NP and NFT counts was removed. Further, compared to brain samples from non-demented individuals, significantly greater GFAP levels were found in samples from individuals diagnosed with Alzheimer's disease, mixed dementia, and vascular mediated dementia. Because elevated levels of GFAP reflect astroglial responses to even subtle forms of neural damage, our data indicate that increments in GFAP may provide independent, supporting evidence for the damage underlying dementia, even in the absence of other evidence of neuropathology such as the presence of NPs or NFTs. Our findings underscore the need to look beyond standard neuropathological measures putatively linked to specific neuropathological conditions in efforts to identify common cellular and molecular processes that contribute to dementia.

Consumption of milk and calcium in midlife and the future risk of Parkinson disease

OBJECTIVE

To examine the relation between milk and calcium intake in midlife and the risk of Parkinson disease (PD).

METHODS

Findings are based on dietary intake observed from 1965 to 1968 in 7,504 men ages 45 to 68 in the Honolulu Heart Program. Men were followed for 30 years for incident PD.

RESULTS

In the course of follow-up, 128 developed PD (7.1/10,000 person-years). Age-adjusted incidence of PD increased with milk intake from 6.9/10,000 person-years in men who consumed no milk to 14.9/10,000 person-years in men who consumed >16 oz/day (p = 0.017). After further adjustment for dietary and other factors, there was a 2.3-fold excess of PD (95% CI 1.3 to 4.1) in the highest intake group (>16 oz/day) vs those who consumed no milk. The effect of milk consumption on PD was also independent of the intake of calcium. Calcium from dairy and nondairy sources had no apparent relation with the risk of PD.

CONCLUSIONS

Findings suggest that milk intake is associated with an increased risk of Parkinson disease. Whether observed effects are mediated through nutrients other than calcium or through neurotoxic contaminants warrants further study.

Cognitive Deficits 3 to 6 Years Before Dementia Onset in a Population Sample: The Honolulu-Asia Aging Study

OBJECTIVE

To determine the type of cognitive deficits occurring 3 to 6 years before onset of dementia in a population sample.

DESIGN

A prospective study in which cognitive deficits in participants who had incident dementia at the 6-year follow-up were examined at baseline and 3 years.

SETTING

Honolulu, Hawaii.

PARTICIPANTS

Three thousand seven hundred thirty-four Japanese-American men aged 71 to 93 at baseline. At the 6-year follow-up, there were 52 incident cases of dementia, and 1,559 controls.

MEASUREMENTS

The Cognitive Abilities Screening Instrument (CASI) and a questionnaire on subjective memory problems were administered at baseline. Dementia was assessed at baseline and at 3-year and 6-year follow-ups.

RESULTS

Subjects who had incident dementia at 6-year follow-up, had showed deficits 3 to 6 years earlier in the CASI domain of episodic memory and in the questionnaire covering subjective memory problems. Up to 3 years before onset, there was worsening of the episodic memory deficit from baseline and new deficits in language, verbal fluency, and orientation.

CONCLUSION

Cognitive deficits and awareness of memory problems are frequently present several years before dementia onset. The predictive value of these deficits is not large enough to allow earlier diagnosis of dementia, but information about such deficits may be useful as criteria for mild cognitive impairment.

A 32-Year Prospective Study of Change in Body Weight and Incident Dementia

BACKGROUND

The course of weight loss associated with dementia is unclear, particularly prior to and around the onset of the clinical syndrome.

OBJECTIVE

To compare the natural history of weight change from mid to late life in men with and without dementia in late life.

DESIGN AND SETTING

The Honolulu-Asia Aging Study, a 32-year, prospective, population-based study of Japanese American men who had been weighed on 6 occasions between 1965 and 1999 and who had been screened for dementia 3 times between 1991 and 1999.

PARTICIPANTS

Of 1890 men (aged 77-98 years), 112 with incident dementia were compared with 1778 without dementia at the sixth examination (1997-1999).

MAIN OUTCOME MEASURE

Weight change up to and including the sixth examination was treated as the dependent variable and estimated using a repeated measures analysis.

RESULTS

Groups with and without dementia did not differ with respect to baseline weight or change in weight from mid to late life (first 26 years' follow-up). In the late-life examinations (final 6 years), mean age- and education-adjusted weight loss was -0.22 kg/y (95% confidence intervals, -0.26 to -0.18) in participants without dementia. Men with incident dementia at the same examination had an additional yearly weight loss of -0.36 kg (95% confidence interval, -0.53 to -0.19). This was not changed substantially with adjustment for risk factors for vascular disease or functional impairment and was significant for both Alzheimer disease and vascular dementia subtypes.

CONCLUSIONS

Dementia-associated weight loss begins before the onset of the clinical syndrome and accelerates by the time of diagnosis. The potential impact on prognosis should be considered in the case of elderly persons at risk for dementia.

Parkinsonian signs and substantia nigra neuron density in decendents elders without PD

Substantia nigra (SN) neurons were counted on single, transverse caudal midbrain sections from 217 male participants in the Honolulu-Asia Aging Study, aged 74-97 years at death. Quadrants areas within the SN were determined with a planimeter and neuronal density was expressed as neurons/mm(2) for 10 Parkinson's disease (PD) cases, 29 incidental Lewy body cases, and 178 controls with neither condition. Mean densities in all quadrants were significantly lower in the PD group compared with the other groups (p = 0.006). This relationship was strongest in the ventrolateral quadrant. In a subgroup of 50 controls who were examined with the Unified Parkinson's Disease Rating Scale an average of 2.1 years prior to death, there was an association of stooped posture (p = 0.009), postural instability (p = 0.013), body bradykinesia (p = 0.048), and gait disturbance (p = 0.05) with neuron density in the dorsolateral quadrant; and impaired speech (p = 0.014), abnormal facial expression (p = 0.022), and difficulty rising from a chair (p = 0.032) with neuron density in the dorsomedial quadrant. There was a significant association of increasing number of signs present with decreasing neuron density in both quadrants (p = 0.001 for trend). Low SN neuron density may be the basis for parkinsonian signs in the elderly without PD.

Walking and dementia in physically capable elderly men

CONTEXT

Evidence suggests that physical activity may be related to the clinical expression of dementia. Whether the association includes low-intensity activity such as walking is not known.

OBJECTIVE

To examine the association between walking and future risk of dementia in older men.

DESIGN

Prospective cohort study.

SETTING AND PARTICIPANTS

Distance walked per day was assessed from 1991 to 1993 in 2257 physically capable men aged 71 to 93 years in the Honolulu-Asia Aging Study. Follow-up for incident dementia was based on neurological assessment at 2 repeat examinations (1994-1996 and 1997-1999).

MAIN OUTCOME MEASURES

Overall dementia, Alzheimer disease, and vascular dementia.

RESULTS

During the course of follow-up, 158 cases of dementia were identified (15.6/1000 person-years). After adjusting for age, men who walked the least (<0.25 mile/d) experienced a 1.8-fold excess risk of dementia compared with those who walked more than 2 mile/d (17.8 vs 10.3/1000 person-years; relative hazard [RH], 1.77; 95% confidence interval [CI], 1.04-3.01). Compared with men who walked the most (>2 mile/d), an excess risk of dementia was also observed in those who walked 0.25 to 1 mile/d (17.6 vs 10.3/1000 person-years; RH, 1.71; 95% CI, 1.02-2.86). These associations persisted after accounting for other factors, including the possibility that limited amounts of walking could be the result of a decline in physical function due to preclinical dementia.

CONCLUSIONS

Findings suggest that walking is associated with a reduced risk of dementia. Promoting active lifestyles in physically capable men could help late-life cognitive function.

Fasting insulin and incident dementia in an elderly population of Japanese-American men

OBJECTIVE

To evaluate the association of fasting insulin level to incident dementia in a cohort of elderly men.

METHODS

Data are from the Honolulu-Asia Aging Study, a community-based study of Japanese-American men, aged 71 to 91 years in 1991. Serum insulin was measured in 1991 and participants were grouped based on their insulin levels. Dementia was ascertained in 1991, 1994, and 1996 according to international guidelines. The 2,568 men dementia-free in 1991 were reexamined in 1994 and 1996; 244 new cases of dementia were diagnosed. Survival analysis with age as the time scale was used to estimate the risk (hazard ratio [HR] and 95% CI) for incident dementia associated with levels of insulin.

RESULTS

The risk of dementia was increased at the two extremes of the insulin distribution (lower and upper 15th percentiles). Compared to the rest of the cohort subjects in the lowest 15th percentile and highest 15th percentile had an increased risk for dementia (HR = 1.54, CI 1.11 to 2.11 and HR = 1.54, CI 1.05 to 2.26). In men with insulin levels <22.2 mIU/L the risk for dementia decreased with increased levels of insulin (HR = 0.76, CI 0.72 to 0.79 for each increase of one logarithmic unit -2.72 mIU/L of insulin). In men with insulin levels >/=22.2 mIU/L the risk for dementia increased with increasing levels of insulin (HR = 1.64, CI = 1.07 to 2.52 for each 2.72 mIU/L).

CONCLUSIONS

Both low and high levels of insulin are associated with an increased risk of developing dementia.

Midlife blood pressure and the risk of hippocampal atrophy: the Honolulu Asia Aging Study

Hippocampal atrophy (HA) is usually attributed to the neurofibrillary tangles and neuritic plaques of Alzheimer disease. However, the hippocampus is vulnerable to global ischemia, which may lead to atrophy. We investigated the association of midlife blood pressure (BP) and late-life HA in a sample of Japanese-American men born between 1900 and 1919. BP was measured on 3 occasions between 1965 and 1971. In 1994 to 1996 a subsample underwent magnetic resonance imaging (MRI) of the brain. Hippocampal volume was estimated by manually drawing regions of interest on relevant scan slices; HA was defined as the lowest quartile of hippocampal volume. Also assessed on the MRI were cortical and subcortical infarcts, lacunes, and white matter hyperintensities. The risk (OR, 95% CI) was estimated for HA associated with systolic (<140 versus > or =140 mm Hg) and diastolic (<90 versus > or =90 mm Hg) BP and with antihypertensive treatment. Analyses were adjusted for sociodemographic factors, other cardiovascular risk factors, apolipoprotein E allele, and correlated brain pathology. Those never treated with antihypertensive medication had a significantly increased risk for HA (OR 1.7; CI=1.12; 2.65). The nontreated subjects with high systolic BP had an increased risk (OR=1.98; CI=0.89; 4.39) for HA. Results were similar for untreated men with high diastolic BP (OR=3.51; CI=1.26; 9.74). In conclusion, treatment with antihypertensive treatment modifies the association of BP and HA, such that high levels of BP adversely affect the hippocampus in persons never treated with antihypertensives.

Midlife dietary intake of antioxidants and risk of late-life incident dementia: the Honolulu-Asia Aging Study

Antioxidants have been hypothesized to protect against Alzheimer's disease, but studies conducted in late life have been inconsistent. Risk factors measured in midlife may better predict dementia in late life because they are less affected by the disease process. The authors examined the association of midlife dietary intake of antioxidants to late-life dementia and its subtypes. Data were obtained from the Honolulu-Asia Aging Study, a prospective community-based study of Japanese-American men who were aged 45-68 years in 1965-1968, when a 24-hour dietary recall was administered. The analysis included 2,459 men with complete dietary data who were dementia-free at the first assessment in 1991-1993 and were examined up to two times for dementia between 1991 and 1999. The sample included 235 incident cases of dementia (102 cases of Alzheimer's disease, 38 cases of Alzheimer's disease with contributing cerebrovascular disease, and 44 cases of vascular dementia). Relative risks by quartile of intake were calculated using Cox proportional hazards models with age as the time scale, after adjustment for sociodemographic and lifestyle factors, cardiovascular risk factors, other dietary constituents, and apolipoprotein E e4. Intakes of beta-carotene, flavonoids, and vitamins E and C were not associated with the risk of dementia or its subtypes. This analysis suggests that midlife dietary intake of antioxidants does not modify the risk of late-life dementia or its most prevalent subtypes.

Environmental, life-style, and physical precursors of clinical Parkinson's disease: recent findings from the Honolulu-Asia Aging Study

BACKGROUND

Increased westernization with Japanese migration to the U. S. in the early 20(th) century is thought to have altered the risk of cardiovascular disease. Whether similar effects include changes in the risk of Parkinson's disease (PD) is not clear. This report describes the relations between environmental, life-style, and physical attributes and the incidence of PD that have been observed in the Honolulu-Asia Aging Study.

METHODS

Beginning in 1965, environmental, life-style, and physical attributes were recorded at selected examinations in a cohort of 8,006 Japanese-American men. Subjects were followed for clinical PD.

FINDINGS

During 30 years of follow- up, PD was observed in 137 men. Overall incidence (7.1/10,000 person-years) was generally higher than in Asia and similar to rates observed in Europe and the U. S. Precursors of PD included constipation, adiposity, years worked on a sugar or pineapple plantation, years of exposure to pesticides, and exposure to sugar cane processing. Factors showing an inverse association with PD included coffee intake and cigarette smoking. Among dietary factors, carbohydrates increased the risk of PD while the intake of polyunsaturated fats appeared protective. Total caloric intake, saturated and monounsaturated fats, protein, niacin, riboflavin, beta-carotene, vitamins A, B, and C, dietary cholesterol, cobalamin, alpha-tocopherol, and pantothenic acid showed no clear relation with clinical PD.

INTERPRETATION

Findings suggest that several environmental, life-style, and physical attributes appear to be precursors of PD. Whether patterns of precursors can be used to identify individuals at high risk of future PD or can broaden the scope of early interventions or recruitment into neuroprotective trials warrants further study.

AD lesions and infarcts in demented and non-demented Japanese-American men

Neocortical neuritic plaques and neurofibrillary tangles are hallmark neuropathological lesions of dementia. Concomitant cerebrovascular lesions increase dementia severity in patients meeting neuropathological criteria for Alzheimer's disease and contribute to cognitive impairment in persons with mild entorhinal Alzheimer lesions. This study investigates whether individuals with sparse neocortical neuritic plaques experience increased odds of crossing the threshold to clinical dementia when they have coexistent cerebrovascular lesions. Dementia examinations were given to 3,734 men during the 1991-1993 Honolulu-Asia Aging Study examination and to 2,603 men during the 1994-1996 examination. Lesion quantification was done without clinical data. Among 333 autopsied men, 120 had dementia, 115 had marginal results, and 98 had normal cognition. In men with neurofibrillary tangles, dementia frequency increased with increasing neuritic plaque density, and increased further in the presence of cerebrovascular lesions. The association was strongest in men with sparse neuritic plaques (1-3/mm(2)) where dementia frequency more than doubled with coexistent cerebrovascular lesions (45 vs 20%). Among all dementia cases, 24% were linked to cerebrovascular lesions. Findings suggest cerebrovascular lesions are associated with a marked excess of dementia in cases with low neuritic plaque frequency. Prevention of cerebrovascular lesions may be critically important in preserving late-life cognitive function.

Mid-life smoking and late-life dementia: the Honolulu-Asia Aging Study

We studied the association between mid-life smoking and late-life dementia in the Honolulu Heart Program (1965-1971) and follow-up assessment for dementia (1991-1996) of 3734 Japanese-American men (80% of survivors). Neuropathologic data were available for 218 men. Adjusting for age, education and apolipoprotein E (APOE) genotype, the risk of Alzheimer's disease (AD) in smokers increased with pack-years of smoking at medium (odds ratio (OR)=2.18, 95% confidence interval (CI)=1.07-4.69) and heavy (OR=2.40; 95% CI=1.16-5.17) smoking levels. Very heavy smoking was not associated with AD (OR=1.08; 95% CI=0.43-2.63). Findings were similar when AD cases included those with cerebrovascular disease and for all dementias combined. Adjustment for cardiovascular and respiratory factors or stratification by apolipoprotein E genotype did not change these associations. In an autopsied subsample, the number of neuritic plaques increased with amount smoked. This study suggests that amount smoked is associated with an increasing risk of AD and Alzheimer-type neuropathology up to heavy smoking levels. The lack of association in very heavy smokers may be due to a hardy survivor effect.

Quantification of regional glial fibrillary acidic protein levels in Alzheimer's disease

OBJECTIVES

Our objectives were to quantify glial fibrillary acidic protein (GFAP) in brains of Alzheimer's disease (AD) cases, and non-AD controls to determine the regions with the most severe gliosis in AD.

MATERIAL AND METHODS

In a case control design, we used an enzyme-linked immunosorbent assay (ELISA) to quantify GFAP in frozen brain from four areas of neocortex in 10 AD cases, 10 age-matched controls, and 10 younger controls from the Honolulu-Asia Aging Study autopsy archive.

RESULTS

Median age at death was 83.5 years for cases and age-matched controls, and 77 years for younger controls. For the AD cases compared with the age-matched controls, levels of GFAP in occipital (P=0.01), parietal (P=0.028), and temporal lobes (P=0.004) (but not frontal) were significantly higher in the cases. The median GFAP excess in AD cases compared with age matched controls was highest in the temporal lobe.

CONCLUSIONS

Regional quantification of GFAP reveals that the glial response is most prominent in the temporal lobe in AD.

CSF Abeta 42 levels correlate with amyloid-neuropathology in a population-based autopsy study

OBJECTIVE

To investigate the relationship of amyloid neuropathology to postmortem CSF Abeta 42 levels in an autopsy sample of Japanese American men from the population-based Honolulu-Asia Aging Study.

METHODS

In 1991, participants were assessed and diagnosed with dementia (including subtype) based on published criteria. At death CSF was obtained from the ventricles. Neuritic plaques (NP) and diffuse plaques in areas of the neocortex and hippocampus were examined using Bielschowsky silver stains. Cerebral amyloid angiopathy (CAA) was measured by immunostaining for beta4 amyloid in cerebral vessels in the neocortex. Neuropathologically confirmed AD was diagnosed using Consortium to Establish a Registry for Alzheimer's Disease criteria. In 155 autopsy samples, log transformed linear regression models were used to examine the association of NP and CAA to Abeta 42 levels, controlling for clinical dementia severity, time between diagnosis and death, age at death, brain weight, hours between death and collection of CSF, education, and APOE genotype.

RESULTS

Higher numbers of NP in the neocortex (p trend = 0.001) and in the hippocampus (p trend = 0.03) were strongly associated with lower levels of Abeta 42. Individuals with CAA had lower Abeta 42 levels (beta coefficient = -0.48; 95% CI -0.9, -0.1). Compared to participants with a diagnosis of clinical dementia, those with pathologically confirmed AD had lower Abeta 42 levels (beta coefficient = -0.74; 95% CI -1.4, -0.1).

CONCLUSION

The current study suggests that lower Abeta 42 levels reflect neuropathologic processes implicated in amyloid-related pathologies, such as NP and CAA.

Plantation work and risk of Parkinson disease in a population-based longitudinal study

CONTEXT

Parkinson disease (PD) has an unknown cause; however, convincing evidence is emerging that indicates pesticides can selectively injure the dopaminergic system in laboratory animals. Retrospective studies in humans demonstrate a link between exposure to agricultural lifestyle factors and PD.

OBJECTIVE

To determine whether working on a plantation in Hawaii and exposure to pesticides are associated with an increased risk of PD decades later.

DESIGN AND SETTING

Prospective cohort study based on the island of Oahu, Hawaii, with 30 years of follow-up. Years of work on a plantation were assessed by questionnaire at study enrollment in 1965. Self-reported information on pesticide exposure was collected at a separate examination 6 years later.

PARTICIPANTS

Participants were 7986 Japanese American men born between 1900 and 1919 who were enrolled in the longitudinal Honolulu Heart Program.

MAIN OUTCOME MEASURES

Incident PD was determined by medical record review or by an examination conducted by a study neurologist at a later date.

RESULTS

During follow-up, 116 men developed PD. Age-adjusted incidence increased significantly among men who worked more than 10 years on a plantation. The relative risk of PD was 1.0 (95% confidence interval, 0.6-1.6), 1.7 (95% confidence interval, 0.8-3.7), and 1.9 (95% confidence interval, 1.0-3.5) for men who worked on a plantation 1 to 10 years, 11 to 20 years, and more than 20 years compared with men who never did plantation work (P =.006, test for trend). Age-adjusted incidence of PD was higher in men exposed to pesticides than in men not exposed to pesticides although this was not statistically significant (P =.10, test for trend).

CONCLUSION

These longitudinal observations regarding plantation work in Hawaii support case-control studies suggesting that exposure to pesticides increases the risk of PD.

Midlife adiposity and the future risk of Parkinson's disease

BACKGROUND

Evidence suggests that nigrostriatal system disorders are associated with PD and adiposity. Whether patterns of adiposity coexist or predate clinical PD is unknown. This report examines the relation between midlife adiposity and the risk of PD.

METHODS

Measurement of adiposity occurred from 1965 to 1968 in 7,990 men in the Honolulu Heart Program (aged 45 to 68 years and without PD). Adiposity measures included body mass index (BMI), subscapular skinfold thickness (SSF), and triceps skinfold thickness (TSF). Follow-up for incident PD occurred over a 30-year period.

RESULTS

During the course of follow-up, PD was observed in 137 men. Among the measures of adiposity, age-adjusted incidence of PD increased threefold from 3.7/10,000 person-years in the bottom quartile of TSF (1 to 5 mm) to 11.1/10,000 person-years in the top quartile (11 to 32 mm, p < 0.001). Effects of TSF on PD were independent of cigarette smoking, coffee consumption, physical activity, daily caloric and fat intake, and the other measures of adiposity (p < 0.001). Whereas rates of PD were lowest in the bottom quartile of BMI and SSF vs higher quartiles, associations with PD were weaker than they were for TSF. The effect of TSF on clinical onset before age 65 years was similar to the effect that was observed in later life.

CONCLUSIONS

Increased triceps skinfold thickness measured in midlife is associated with an elevated risk of future PD. Whether patterns of adiposity reflect a unique metabolic pathology in individuals at a high risk of PD warrants further study.

Early inflammation and dementia: a 25-year follow-up of the Honolulu-Asia Aging Study

Inflammatory responses are associated with cardiovascular disease and may be associated with dementing disease. We evaluated the long-term prospective association between dementia and high-sensitivity C-reactive protein, a nonspecific marker of inflammation. Data are from the cohort of Japanese American men who were seen in the second examination of the Honolulu Heart Program (1968-1970) and subsequently were reexamined 25 years later for dementia in the Honolulu-Asia Aging Study (1991-1996). In a random subsample of 1,050 Honolulu-Asia Aging Study cases and noncases, high-sensitivity C-reactive protein concentrations were measured from serum taken at the second examination; dementia was assessed in a clinical examination that included neuroimaging and neuropsychological testing and was evaluated using international criteria. Compared with men in the lowest quartile (<0.34mg/L) of high-sensitivity C-reactive protein, men in the upper three quartiles had a 3-fold significantly increased risk for all dementias combined, Alzheimer's disease, and vascular dementia. For vascular dementia, the risk increased with increasing quartile. These relations were independent of cardiovascular risk factors and disease. These data support the view that inflammatory markers may reflect not only peripheral disease, but also cerebral disease mechanisms related to dementia, and that these processes are measurable long before clinical symptoms appear.