Alzheimer Disease: Wolf PA

Jarvik L, LaRue A, Blacker D, Gatz M, Kawas C, McArdle JJ, Morris JC, Mortimer JA, Ringman JM, Ercoli L, Freimer N, Gokhman I, Manly JJ, Plassman BL, Rasgon N, Roberts JS, Sunderland T, Swan GE, Wolf PA, Zonderman AB. · Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, CA 90095, USA. · Alzheimer Dis Assoc Disord. · Pubmed #18317242 No free full text.

Abstract: Children of persons with Alzheimer disease (AD), as a group, face an increased risk of developing AD. Many of them, throughout their adult lives, seek input on how to reduce their chances of one day suffering their parent's fate. We examine the state of knowledge with respect to risk and protective factors for AD and recommend a research agenda with special emphasis on AD offspring.

Schaefer EJ, Bongard V, Beiser AS, Lamon-Fava S, Robins SJ, Au R, Tucker KL, Kyle DJ, Wilson PW, Wolf PA. · Lipid Metabolism Laboratory, Jean Mayer US Department of Agriculture Human Nutrition REsearch Center on Aging, Tuffs University, Boston, MA 02111, USA. · Arch Neurol. · Pubmed #17101822 links to  free full text

Abstract: BACKGROUND: Docosahexaenoic acid (DHA) is an abundant fatty acid in the brain. In the diet, DHA is found mostly in fatty fish. The content of DHA has been shown to be decreased in the brain and plasma of patients with dementia. OBJECTIVE: To determine whether plasma phosphatidylcholine (PC) DHA content is associated with the risk of developing dementia. Design, Setting, and PARTICIPANTS: A prospective follow-up study in 899 men and women who were free of dementia at baseline, had a median age of 76.0 years, and were followed up for a mean of 9.1 years for the development of all-cause dementia and Alzheimer disease. MAIN OUTCOME MEASURES: Plasma PC fatty acid levels were measured at baseline. Cox proportional regression analysis was used to assess relative risks of all-cause dementia and Alzheimer disease according to baseline plasma levels. RESULTS: Ninety-nine new cases of dementia (including 71 of Alzheimer disease) occurred during the follow-up. After adjustment for age, sex, apolipoprotein E epsilon4 allele, plasma homocysteine concentration, and education level, subjects in the upper quartile of baseline plasma PC DHA levels, compared with subjects in the lower 3 quartiles, had a relative risk of 0.53 of developing all-cause dementia (95% confidence interval, 0.29-0.97; P=.04) and 0.61 of developing Alzheimer disease (95% confidence interval, 0.31-1.18; P=.14). Subjects in the upper quartile of plasma PC DHA levels had a mean DHA intake of 0.18 g/d and a mean fish intake of 3.0 servings per week (P<.001) in a subset of 488 participants. We found no other significant associations. CONCLUSION: The top quartile of plasma PC DHA level was associated with a significant 47% reduction in the risk of developing all-cause dementia in the Framingham Heart Study.

Elias MF, Beiser A, Wolf PA, Au R, White RF, D'Agostino RB. · Department of Mathematics and Statistics, Statistical Consulting Unit, 111 Cummington St, Boston University College of Arts and Sciences, Boston, MA 02215, USA. · Arch Neurol. · Pubmed #10867777 links to  free full text

Abstract: OBJECTIVES: To relate performance on tests of cognitive ability to the subsequent development of probable Alzheimer disease (pAD) and to identify the pattern of earliest changes in cognitive functioning associated with a diagnosis of pAD. DESIGN: From May 1975 to November 1979, a screening neuropsychological battery was administered to Framingham Study participants. They were followed up prospectively for 22 years and examined at least every 2 years for the development of pAD. SETTING: A community-based center for epidemiological research. PARTICIPANTS: Subjects were 1076 participants of the Framingham Study aged 65 to 94 years who were free of dementia and stroke at baseline (initial) neuropsychological testing. MAIN OUTCOME MEASURE: Presence or absence of pAD during a 22-year surveillance period was related to test performance at initial neuropsychological testing. RESULTS: Lower scores for measures of new learning, recall, retention, and abstract reasoning obtained during a dementia-free period were associated with the development of pAD. Lower scores for measures of abstract reasoning and retention predicted pAD after a dementia-free period of 10 years. CONCLUSIONS: The "preclinical phase" of detectable lowering of cognitive functioning precedes the appearance of pAD by many years. Measures of retention of information and abstract reasoning are among the strongest predictors of pAD when the interval between initial assessment and the development of pAD is long. Arch Neurol. 2000.

Tan ZS, Beiser A, Vasan RS, Au R, Auerbach S, Kiel DP, Wolf PA, Seshadri S. · Department of Medicine, Gerontology Division, Beth Israel Deaconess Medical Center, 110 Francis St, LMOB 1A, Boston, MA 02215, USA. · Arch Intern Med. · Pubmed #18663163 links to  free full text

Abstract: BACKGROUND: Clinical hypothyroidism and hyperthyroidism are recognized causes of reversible dementia, but previous studies relating thyrotropin levels to cognitive performance in clinically euthyroid persons have yielded inconsistent results. METHODS: We related serum thyrotropin concentrations measured at baseline (March 1977-November 1979) to the risk of Alzheimer disease (AD) in 1864 cognitively intact, clinically euthyroid Framingham original cohort participants (mean age, 71 years; 59% women). Sex-specific Cox proportional hazards models were constructed using tertiles of thyrotropin concentration (tertile 2 as the referent) and adjusting for age, apolipoprotein E epsilon4 allele status, educational level, plasma homocysteine level, current smoking, body mass index, prevalent stroke, and atrial fibrillation. RESULTS: During a mean follow-up of 12.7 years (range, 1-25 years), 209 participants (142 women) developed AD. Women in the lowest (<1.0 mIU/L) and highest (>2.1 mIU/L) tertiles of serum thyrotropin concentration were at increased risk for AD (multivariate-adjusted hazard ratio, 2.39 [95% confidence interval, 1.47-3.87] [P < .001] and 2.15 [95% confidence interval, 1.31-3.52] [P = .003], respectively) compared with those in the middle tertile. Thyrotropin levels were not related to AD risk in men. Analyses excluding individuals receiving thyroid supplementation did not significantly alter these relationships. In analyses limited to participants with serum thyrotropin levels of 0.1 to 10.0 mIU/L, the U-shaped relationship between thyrotropin level and AD risk was maintained in women but not when analyses were limited to those with thyrotropin levels of 0.5 to 5.0 mIU/L. CONCLUSION: Low and high thyrotropin levels were associated with an increased risk of incident AD in women but not in men.

Szekely CA, Green RC, Breitner JC, Østbye T, Beiser AS, Corrada MM, Dodge HH, Ganguli M, Kawas CH, Kuller LH, Psaty BM, Resnick SM, Wolf PA, Zonderman AB, Welsh-Bohmer KA, Zandi PP. · Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA. · Neurology. · Pubmed #18509093 No free full text.

Abstract: INTRODUCTION: Observational studies show reduced incidence of Alzheimer dementia (AD) in users of nonsteroidal anti-inflammatory drugs (NSAIDs). One hypothesis holds that the subset of NSAIDs known as selective A beta(42)-lowering agents (SALAs) is responsible for this apparent reduction in AD risk. METHODS: We pooled individual-level data from six prospective studies to obtain a sufficient sample to examine AD risk in users of SALA vs non-SALA NSAIDs. RESULTS: Of 13,499 initially dementia-free participants (70,863 person-years), 820 developed incident AD. Users of NSAIDs (29.6%) showed reduced risk of AD (adjusted hazard ratio [aHR] 0.77, 95% CI 0.65-0.91). The point estimates were similar for SALAs (aHR 0.87, CI 0.72-1.04) and non-SALAs (aHR 0.75, CI 0.56-1.01). Because 573 NSAID users (14.5%) reported taking both a SALA and non-SALA, we examined their use alone and in combination. Resulting aHRs were 0.82 (CI 0.67-0.99) for SALA only, 0.60 (CI 0.40-0.90) for non-SALA only, and 0.87 (CI 0.57-1.33) for both NSAIDs (Wald test for differences, p = 0.32). The 40.7% of participants who used aspirin also showed reduced risk of AD, even when they used no other NSAIDs (aHR 0.78, CI 0.66-0.92). By contrast, there was no association with use of acetaminophen (aHR 0.93, CI 0.76-1.13). CONCLUSIONS: In this pooled dataset, nonsteroidal anti-inflammatory drug (NSAID) use reduced the risk of Alzheimer dementia (AD). However, there was no apparent advantage in AD risk reduction for the subset of NSAIDs shown to selectively lower A beta(42), suggesting that all conventional NSAIDs including aspirin have a similar protective effect in humans.

Tan ZS, Beiser AS, Vasan RS, Roubenoff R, Dinarello CA, Harris TB, Benjamin EJ, Au R, Kiel DP, Wolf PA, Seshadri S. · Department of Medicine, Institute for Aging Research, Hebrew Senior Life, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02131, USA. · Neurology. · Pubmed #17536046 No free full text.

Abstract: OBJECTIVE: To examine whether serum cytokines and spontaneous production of peripheral blood mononuclear cell (PBMC) cytokines are associated with the risk of incident Alzheimer disease (AD). METHODS: We followed 691 cognitively intact community-dwelling participants (mean age 79 years, 62% women) and related PBMC cytokine production (tertiles of spontaneous production of interleukin 1 [IL-1], IL-1 receptor antagonist, and tumor necrosis factor alpha [TNF-alpha]) and serum C-reactive protein and interleukin 6 (IL-6) to the risk of incident AD. RESULTS: Adjusting for clinical covariates, individuals in the top two tertiles (T2 and T3) of PBMC production of IL-1 or the top tertile (T3) of PBMC production of TNF-alpha were at increased risk of developing AD (multivariable-adjusted hazard ratio [HR] for IL-1 T2 = 2.84, 95% CI 1.09 to 7.43; p = 0.03 and T3 = 2.61, 95% CI 0.96 to 7.07; p = 0.06; for TNF-alpha, adjusted HR for T2 = 1.30, 95% CI 0.53 to 3.17; p = 0.57 and T3 = 2.59, 95% CI 1.09 to 6.12; p = 0.031]) compared with those in the lowest tertile (T1). Interpretation: Higher spontaneous production of interleukin 1 or tumor necrosis factor alpha by peripheral blood mononuclear cells may be a marker of future risk of Alzheimer disease (AD) in older individuals. These data strengthen the evidence for a pathophysiologic role of inflammation in the development of clinical AD.

Jefferson AL, Massaro JM, Wolf PA, Seshadri S, Au R, Vasan RS, Larson MG, Meigs JB, Keaney JF, Lipinska I, Kathiresan S, Benjamin EJ, DeCarli C. · Department of Neurology, Boston University School of Medicine, Boston, MA 02118, USA. · Neurology. · Pubmed #17389308 No free full text.

Abstract: BACKGROUND: Systemic inflammation is associated with ischemia and Alzheimer disease (AD). We hypothesized that inflammatory biomarkers would be associated with neuroimaging markers of ischemia (i.e., white matter hyperintensities [WMH]) and AD (i.e., total brain volume [TCB]). METHODS: MRI WMH and TCB were quantified on 1,926 Framingham Offspring participants free from clinical stroke, TIA, or dementia (mean age 60 +/- 9 years; range 35 to 85 years; 54% women) who underwent measurement of a circulating inflammatory marker panel, including CD40 ligand, C-reactive protein, interleukin-6 (IL-6), soluble intracellular adhesion molecule-1, monocyte chemoattractant protein-1, myeloperoxidase, osteoprotegerin (OPG), P-selectin, tumor necrosis factor-alpha (TNFalpha), and tumor necrosis factor receptor II. To account for head size, both TCB (TCBV) and WMH (WMH/TCV) were divided by total cranial volume. We used multivariable linear regression to relate 10 log-transformed inflammatory biomarkers to brain MRI measures. RESULTS: In multivariable models, inflammatory markers as a group were associated with TCBV (p < 0.0001) but not WMH/TCV (p = 0.28). In stepwise models adjusted for clinical covariates with backwards elimination of markers, IL-6 and OPG were inversely associated with TCBV; TNFalpha was inversely related to TCBV in a subset of 1,430 participants. Findings were similar in analyses excluding individuals with prevalent cardiovascular disease. The relations between TCBV and inflammatory markers were modified by both sex and age, and generally were more pronounced in men and in older individuals. CONCLUSIONS: Although our observational cross-sectional data cannot establish causality, they are consistent with the hypothesis that higher inflammatory markers are associated with greater atrophy than expected for age.

Akomolafe A, Beiser A, Meigs JB, Au R, Green RC, Farrer LA, Wolf PA, Seshadri S. · Department of Medicine, Morehouse School of Medicine, Atlanta, GA, USA. · Arch Neurol. · Pubmed #17101823 links to  free full text

Abstract: BACKGROUND: Diabetes mellitus (DM) could increase the risk of Alzheimer disease (AD) through several biologically plausible pathways, but the relationship between DM and the development of AD remains uncertain. OBJECTIVE: To compare the risk of developing AD in subjects with and without DM. DESIGN: Prospective community-based cohort study. PARTICIPANTS: Framingham Study Original cohort participants who were dementia free and attended the 16th biennial examination (n = 2210 persons, 1325 women; mean age, 70 years). MAIN OUTCOME MEASURES: Relative risk of incident AD (criteria from the National Institute of Neurological and Communicative Diseases and Stroke/Alzheimer's Disease and Related Disorders Association) associated with baseline DM (casual plasma glucose >or=200 mg/dL [>or=11.1 mmol/L] or use of insulin or a hypoglycemic drug) in overall group and within subgroups defined by apolipoprotein E genotype and plasma homocysteine levels; models were adjusted for age, sex, and cardiovascular risk factors. RESULTS: At baseline, 202 participants (9.1%) had DM. During the follow-up period (mean, 12.7 years; range, 1-20 years), 17 of 202 persons with DM (8.4%) and 220 of 2008 persons without DM (11.0%) developed AD, yielding a relative risk of 1.15 (95% confidence interval, 0.65-2.05). Among subjects without an apolipoprotein E epsilon4 allele or elevated plasma homocysteine levels, 44 of 684 persons (6.4%) developed AD; relative risk for AD comparing diabetic patients with nondiabetic patients was 2.98 (95% confidence interval, 1.06-8.39; P = .03). The effect was strongest in persons aged 75 years or older with a relative risk of 4.77 (95% confidence interval, 1.28-17.72; P = .02). CONCLUSION: Diabetes mellitus did not increase the risk of incident AD in the Framingham cohort overall; however, DM may be a risk factor for AD in the absence of other known major AD risk factors.

McKee AC, Au R, Cabral HJ, Kowall NW, Seshadri S, Kubilus CA, Drake J, Wolf PA. · Department of Neurology and Pathology, Boston University School of Medicine, Bedford Veterans Administration Medical Center, MA 01730, USA. · J Neuropathol Exp Neurol. · Pubmed #16783172 No free full text.

Abstract: The transition from normal aging to mild cognitive impairment to Alzheimer disease (AD) is often indistinct. Imaging studies suggest early changes in posterior brain regions, including posterior temporoparietal and occipital cortex, but pathologic studies show initial changes in the medial temporal lobe with progressive neocortical involvement as cognition deteriorates. We evaluated the regional distribution of AD pathology in 41 elderly brain donors from the Framingham Heart Study who were cognitively intact, mildly impaired, or demented on the basis of probable AD. We found that 52% of the cognitively intact subjects, and all subjects with mild cognitive impairment or dementia, had dense neurofibrillary tangles (NFTs), neuropil threads, and tau-immunoreactive neurites surrounding neuritic plaques (NPs) in visual association cortex Brodmann area 19. All cognitively intact subjects with area 19 NFTs also had dense core NP and beta amyloid (Abeta) angiopathy in area 19. Area 19 pathology was occasionally present in the absence of substantial pathology in the hippocampus or entorhinal cortex and was not correlated with medial temporal lobe pathology. Dense AD pathology in area 19 is present in some cognitively intact subjects with preclinical AD. The unique metabolic, connectional, and vascular features of this region may confer enhanced vulnerability to neurodegeneration.

Seshadri S, Beiser A, Kelly-Hayes M, Kase CS, Au R, Kannel WB, Wolf PA. · Department of Neurology, School of Medicine, Boston University, Boston, MA 02118-2526, USA. · Stroke. · Pubmed #16397184 links to  free full text

Abstract: BACKGROUND AND PURPOSE: The lifetime risk (LTR) of stroke has not been reported for the United States population; such data would assist public education and health planning. METHODS: Framingham Original cohort participants (n=4897) who were stroke- and dementia-free at 55 years of age were followed biennially for up to 51 years (115 146 person years). We estimated the sex-specific 10-, 20-, and 30-year risks and LTR of developing a stroke by baseline age and blood pressure (BP) and compared it with the risk of developing Alzheimer disease (AD). RESULTS: A total of 875 participants (522 women) developed a first-ever stroke; 749 (448 women) had an ischemic stroke. LTR of stroke was high and remained similar at ages 55, 65, and 75 years, approximating 1 in 5 for women and 1 in 6 for men. Participants with a normal BP (<120/80 mm Hg) had approximately half the LTR of stroke compared with those with high BP (> or =140/90 mm Hg). The LTR of AD at age 65 (292 participants; 211 women) approximated 1 in 5 for women and 1 in 10 for men. The LTR of developing either stroke or dementia approximated 1 in 3 in both sexes. CONCLUSIONS: The LTR of stroke in middle-aged adults is 1 in 6 or more, which is equal to or greater than the LTR of AD. Women had a higher risk because of longer life expectancy. BP is a significant determinant of the LTR of stroke, and promotion of normal BP levels in the community might be expected to substantially reduce this risk.

Tan ZS, Seshadri S, Beiser A, Zhang Y, Felson D, Hannan MT, Au R, Wolf PA, Kiel DP. · Division on Aging, Harvard Medical School, Beth Israel Deaconess Medical Center, 110 Francis Street, Boston, MA 02215, USA. · Arch Neurol. · Pubmed #15642856 links to  free full text

Abstract: BACKGROUND: Some, but not all, studies have suggested that estrogen replacement therapy has a beneficial effect on cognition in postmenopausal women. Bone mineral density (BMD) is a potential surrogate marker for cumulative estrogen exposure and has been associated with cognitive performance and risk of cognitive deterioration. OBJECTIVE: To examine whether low BMD in elderly individuals is associated with an increased risk of developing Alzheimer disease (AD). DESIGN, SETTING, AND PARTICIPANTS: Community-based prospective cohort study of 987 subjects (610 women) who were cognitively intact and had baseline BMD measured at the femoral neck, the trochanter, and the radial shaft between 1988 and 1989. MAIN OUTCOME MEASURES: Incidence of AD and all-cause dementia during an 8-year follow-up period. RESULTS: Women in the lowest quartile of femoral neck BMD had more than twice the incidence of AD (hazard ratio, 2.04; 95% confidence interval, 1.11-3.75) and all-cause dementia (hazard ratio, 2.01; 95% confidence interval, 1.16-3.49) compared with those in higher quartiles after adjusting for age, sex, apolipoprotein E epsilon4, baseline homocysteine level, education, estrogen use, smoking, and stroke. A similar but statistically nonsignificant relationship was observed between BMD of the femoral trochanter and AD, while no such relationship was seen between radial BMD and AD or all-cause dementia. In men, there was a trend toward an inverse relationship between BMD and the risk of AD, but the relationship was not statistically significant at any of the 3 sites. CONCLUSIONS: Low femoral neck BMD was associated with approximately 2 times the risk of AD and all-cause dementia in women but not men, suggesting the possibility that cumulative estrogen exposure may influence the risk of developing AD. Additional studies are needed to confirm this correlation.

Seshadri S, Wolf PA. · Department of Neurology, Boston University School of Medicine, Boston, MA, USA. · Lancet Neurol. · Pubmed #12849292 No free full text.

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Tan ZS, Seshadri S, Beiser A, Wilson PW, Kiel DP, Tocco M, D'Agostino RB, Wolf PA. · Division on Aging, Harvard Medical School, Boston, MA, USA. · Arch Intern Med. · Pubmed #12742802 links to  free full text

Abstract: BACKGROUND: Previous studies examining the association of plasma cholesterol levels with the risk for development of Alzheimer disease (AD) have been inconclusive. We examined the impact of baseline and lifetime plasma total cholesterol levels averaged across many years on the risk for AD in a large, population-based cohort. METHODS: Five thousand two hundred nine subjects from the Framingham Study original cohort underwent biennial evaluation for cardiovascular risk factors since 1950, with estimations of serum total cholesterol levels at 19 of these 25 biennial examinations. The study sample consisted of 1026 subjects from this cohort who were alive and free of stroke and dementia at examination cycle 20 (1988-1989) and had undergone apolipoprotein E (APOE) genotyping. The main outcome measure was incident AD diagnosed using standard criteria, according to average total cholesterol levels across biennial examination cycles 1 to 15 and baseline total cholesterol level measured at the 20th biennial examination cycle. RESULTS: Alzheimer disease developed in 77 subjects from 1992 to 2000. After adjustment for age, sex, APOE genotype, smoking, body mass index (calculated as weight in kilograms divided by the square of height in meters), coronary heart disease, and diabetes, we found no significant association between the risk for incident AD and average cholesterol level at biennial examination cycles 1 to 15 (hazard ratio per 10-mg/dL [0.3-mmol/L] rise, 0.95; 95% confidence interval, 0.87-1.04) or baseline total cholesterol level at examination 20 (hazard ratio, 0.97; 95% confidence interval, 0.90-1.05). CONCLUSION: In this large, population-based cohort, baseline and long-term average serum total cholesterol levels were not associated with the risk for incident AD.

Gates GA, Beiser A, Rees TS, D'Agostino RB, Wolf PA. · Department of Otolaryngology-Head and Neck Surgery, University of Washington School of Medicine, Seattle, WA 98195, USA. · J Am Geriatr Soc. · Pubmed #11943044 No free full text.

Abstract: OBJECTIVES: To document the prognostic significance of a central auditory speech-processing deficit for the subsequent onset of probable Alzheimer's disease. DESIGN: Prospective cohort study. SETTING: Framingham Heart Study. PARTICIPANTS: Seven hundred forty dementia-free volunteers from the Framingham Heart Study cohort with symmetric hearing thresholds at biennial examination 15 (1983-1985). MEASUREMENTS: The diagnosis of probable Alzheimer's disease was made prospectively using the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease Related Disorder Association criteria. A central auditory speech-processing deficit was defined as a score of 50% of less correct on the Synthetic Sentence Identification with Ipsilateral Competing Message test in at least one ear with normal word recognition ability in both ears. Cox proportional hazards regression assessed the relationship between a central auditory speech-processing deficit and the age at diagnosis of probable Alzheimer's disease. RESULTS: Forty subjects (5.4%) received a diagnosis of probable Alzheimer's disease during an average of 8.4 years (range 3-12) of follow-up; seven (17.5%) of these had a central auditory speech-processing deficit. The presence of a central auditory speech-processing deficit had an age-adjusted risk ratio for probable Alzheimer's disease of 10.8 (95% CI = 4.6-25.2), and the estimated risk ratio adjusted for age, gender, education level, apolipoprotein allele E4 presence, and hearing level was 23.3 (95% CI =6.6-82.7). A central auditory speech-processing deficit had a positive predictive value for subsequent probable Alzheimer's disease of 47% but the sensitivity was only 17.5%. CONCLUSION: Central auditory speech-processing deficits may be an early manifestation of probable Alzheimer's disease and may precede the onset of dementia diagnosis by many years.

Seshadri S, Beiser A, Selhub J, Jacques PF, Rosenberg IH, D'Agostino RB, Wilson PW, Wolf PA. · Department of Neurology, Boston University School of Medicine, MA 02118-2526, USA. · N Engl J Med. · Pubmed #11844848 links to  free full text

Abstract: BACKGROUND: In cross-sectional studies, elevated plasma homocysteine levels have been associated with poor cognition and dementia. Studies of newly diagnosed dementia are required in order to establish whether the elevated homocysteine levels precede the onset of dementia or result from dementia-related nutritional and vitamin deficiencies. METHODS: A total of 1092 subjects without dementia (667 women and 425 men; mean age, 76 years) from the Framingham Study constituted our study sample. We examined the relation of the plasma total homocysteine level measured at base line and that measured eight years earlier to the risk of newly diagnosed dementia on follow-up. We used multivariable proportional-hazards regression to adjust for age, sex, apolipoprotein E genotype, vascular risk factors other than homocysteine, and plasma levels of folate and vitamins B12 and B6. RESULTS: Over a median follow-up period of eight years, dementia developed in 111 subjects, including 83 given a diagnosis of Alzheimer's disease. The multivariable-adjusted relative risk of dementia was 1.4 (95 percent confidence interval, 1.1 to 1.9) for each increase of 1 SD in the log-transformed homocysteine value either at base line or eight years earlier. The relative risk of Alzheimer's disease was 1.8 (95 percent confidence interval, 1.3 to 2.5) per increase of 1 SD at base line and 1.6 (95 percent confidence interval, 1.2 to 2.1) per increase of 1 SD eight years before base line. With a plasma homocysteine level greater than 14 micromol per liter, the risk of Alzheimer's disease nearly doubled. CONCLUSIONS: An increased plasma homocysteine level is a strong, independent risk factor for the development of dementia and Alzheimer's disease.

Beiser A, D'Agostino RB, Seshadri S, Sullivan LM, Wolf PA. · Department of Epidemiology and Biostatistics, Boston University School of Public Health, Boston, MA 02118, USA. · Stat Med. · Pubmed #10844714 No free full text.

Abstract: The incidence of disease is estimated in medical and public health applications using various different techniques presented in the statistical and epidemiologic literature. Many of these methods have not yet made their way to popular statistical software packages and their application requires custom programming. We present a macro written in the SAS macro language that produces several estimates of disease incidence for use in the analysis of prospective cohort data. The development of the Practical Incidence Estimators (PIE) Macro was motivated by research in Alzheimer's Disease (AD) in the Framingham Study in which the development of AD has been prospectively assessed over an observation period of 24 years. The PIE Macro produces crude and age-specific incidence rates, overall and stratified by the levels of a grouping variable. In addition, it produces age-adjusted rates using direct standardization to the combined group. The user specifies the width of the age groups and the number of levels of the grouping variable. The PIE macro produces estimates of future risk for user-defined time periods and the remaining lifetime risk conditional on survival event-free to user-specified ages. This allows the user to investigate the impact of increasing age on the estimate of remaining lifetime risk of disease. In each case, the macro provides estimates based on traditional unadjusted cumulative incidence, and on cumulative incidence adjusted for the competing risk of death. These estimates and their respective standard errors, are provided in table form and in an output data set for graphing. The macro is designed for use with survival age as the time variable, and with age at entry into the study as the left-truncation variable; however, calendar time can be substituted for the survival time variable and the left-truncation variable can simply be set to zero. We illustrate the use of the PIE macro using Alzheimer's Disease incidence data collected in the Framingham Study.