Biomedical subjects

M X Tang

Publications and source records attributed to M X Tang.

At least 55 records · Page 3Linked to original sources

PubMed1996

Depressed mood and the incidence of Alzheimer's disease in the elderly living in the community.

BACKGROUND: It remains unclear whether depression increases the risk for dementia in the elderly. We evaluated the relationship between depressed mood at baseline and the incidence of dementia, particularly Alzheimer's disease, in the elderly living in the community. METHODS: A total of 1070 elderly individuals, aged 60 years or older, were identified as part of a registry for dementia in the Washington Heights community of North Manhattan, NY. In a prospective, longitudinal design with follow-up for 1 to 5 years, annual physician evaluation and neuropsychological testing were used to assess levels of cognitive impairment and to diagnose dementia. Depressive symptoms were evaluated with the 17-item Hamilton Rating Scale for Depression. Based on clinical considerations and a validity study, a positive score for the depressed mood item was used in statistical analyses. To confirm the results, the total Hamilton Rating Scale for Depression score was also evaluated as the "depression" variable. RESULTS: Of the 1070 subjects, 218 met criteria for dementia at baseline evaluation. In the 852 subjects without dementia, depressed mood was more common in individuals with greater cognitive impairment. In a follow-up study of 478 of these subjects without dementia (mean +/- SD, 2.54 +/- 1.12 years of follow-up), the effect of baseline depressed mood on the end-point diagnosis of dementia (93% had possible or probable Alzheimer's disease) was evaluated in a Cox proportional hazards model. Depressed mood at baseline was associated with an increased risk of incident dementia (relative risk, 2.94; 95% confidence interval, 1.76 to 4.91; P < .001). This effect remained after adjustment for age, gender, education, language of assessment, Blessed Memory Information and Concentration test scores, and Blessed Functional Activity Scale scores (relative risk, 2.05; 95% confidence interval, 1.16 to 3.62; P < .02). Similar results were obtained when the total Hamilton Rating Scale for Depression score was used as the depression variable, with the use of the same covariates (relative risk, 1.07 per point interval; 95% confidence interval, 1.02 to 1.11; P < .01). CONCLUSIONS: Depressed mood moderately increased the risk of developing dementia, primarily Alzheimer's disease. Whether depressed mood is a very early manifestation of Alzheimer's disease, or increases susceptibility through another mechanism, remains to be determined.

Age Factors↗

PubMed1996

Dietary lipids and antioxidants in Parkinson's disease: a population-based, case-control study.

Oxidative stress plays an important role in the pathogenesis of Parkinson's disease (PD). In a population-based, case-control study we examined whether dietary intake of antioxidants and other oxidative compounds was associated with PD. Dietary intake was assessed by a semiquantitative food-frequency questionnaire in 110 PD case patients and 287 control subjects. A higher caloric intake was observed in patients with PD and did not vary with increasing duration of symptoms. Energy-adjusted fat intake was significantly higher among patients with PD than control subjects (p for trend = 0.007). Intake of protein (p for trend = 0.17) and carbohydrates (p for trend = 0.46) did not differ in patients and control subjects. Analyses of the primary sources of fat indicated that increasing intake of animal fats were strongly related to PD (odds ratio, 5.3; 95% confidence interval, 1.8-15.5; p for trend = 0.001). No significant differences were observed for intake of vitamins with antioxidant activity. An increase in the consumption of animal fats among patients with PD is consistent with the hypothesis that oxidative stress and lipid peroxidation are important in the pathogenesis of this disease. No effect of vitamins with antioxidant activity, either from food or supplements, was observed.

Aged↗

PubMed1996

Prevalence of a history of shaking in persons 65 years of age and older: diagnostic and functional correlates.

The purpose of this study was to determine the prevalence and functional and diagnostic correlates of reported shaking in the community-dwelling elderly. We conducted a standardized neurological evaluation of 1,056 nondemented Medicare recipients in Washington Heights-Inwood, Northern Manhattan (New York). Of 1,056 patients, 108 reported shaking (10.2%). The prevalence of reported shaking did not increase with age. It did differ between ethnic groups, but when adjusted for depression and score on the Schwab and England Activities of Daily Living (ADL) scale, this difference was insignificant. The age-adjusted prevalence was similar for women and men. Neurological examination of the 108 who reported shaking showed that 8.3% had tremor at rest, 17.6% had tremor with action, 5.6% had dyskinesia or chorea, and an additional 28.7% had various problems in coordination or movement. The remaining 39.8% had neither tremor nor problems in coordination or movement. Only 2.9% of individuals with reported shaking had Parkinson's disease (PD), 8.7% had essential tremor, and 2.1% had oral-buccal-lingual dyskinesia. Of the remaining 86.3%, 29 (31%) had no identifiable medical condition. Those who reported shaking were less independent with ADLs, regardless of presence of tremor on examination. Shaking is commonly reported by the community-dwelling elderly. It does not necessarily identify individuals with essential tremor and PD, and is related to decreased independence in ADLs.

Activities of Daily Living↗

PubMed1996

Polymorphisms in the human apolipoprotein-J/clusterin gene: ethnic variation and distribution in Alzheimer's disease.

Apolipoprotein-J/clusterin (APOJ/CLI) shares many biological properties with apolipoprotein-E (APOE) including, but not limited to, avid binding with beta-amyloid peptide. Thus, APOJ/CLI warrants scrutiny as a candidate Alzheimer's disease (AD) susceptibility gene. We identified seven nucleotide sequence polymorphisms in APOJ/ CLI, two of which, in exon 7, after the predicted amino acid sequence. The JVIIB variant is an asparagine-to-histidine substitution, which deletes a glycosylation signal at amino acid 317; the JVIIC variant is an aspartate-to-asparagine substitution, which forms a new glycosylation signal at position 328. Both of these coding variants, as well as two neutral polymorphisms in exon 2, were more frequent in African-Americans than Hispanics and were rare in Caucasians. However, no individual coding or noncoding variant was consistently associated with AD. At the population level, APOJ/CLI polymorphisms are frequent among persons of African descent, but probably do not alter susceptibility to AD.

Black or African American↗

PubMed1996

The Clinical Dementia Rating scale: community-based validation of "profound' and "terminal' stages.

The original version of the Clinical Dementia Rating (CDR) scale correlates with other dementia rating scales, and predicts nursing home (NH) admission and death. To validate the extended components of the scale, we analyzed data from subjects participating in a community-based study of dementia. The extended CDR scale also correlated with measures of dementia severity and NH residence. "Profound" and "terminal" stages predicted shortened survival. The extended CDR scale should be useful in studies of the later stages of dementia.

Activities of Daily Living↗

PubMed1996

Risk of Parkinson's disease among first-degree relatives: A community-based study.

OBJECTIVE: To determine the relative risk (RR) and cumulative incidence of idiopathic Parkinson's disease (PD) in first-degree relatives of PD patients compared with relatives of controls from the same geographic region. DESIGN: A family history questionnaire was used to obtain information on all first-degree relatives of cases and controls. A subset of these first-degree relative was also examined. A Cox proportional hazards model with double-censoring techniques for missing information was used to model the RR for PD, adjusting for gender, ethnicity, and relationship to proband. RESULTS: A total of 1,458 first-degree relatives of 233 PD patients were 2.3 times as likely (95% CI = 1.3 to 4.0) as 7,834 relatives of 1,172 controls to develop PD. The cumulative incidence of PD to age 75 among first-degree relatives of PD patients was 2% compared with 1% among first-degree relatives of controls. The risk in male first-degree relatives was higher than in female relatives (RR = 2.0, 95% CI = 1.1 to 3.4) and the risk in relatives of Caucasians was higher than in African-Americans and Hispanics (RR = 2.4, 95% CI = 1.4 to 4.1). Risk for siblings and parents of probands was similar. CONCLUSIONS: Susceptibility to PD is increased in first-degree relatives of both sporadic and familial cases. The pattern of inheritance and the relationship between genetic and environmental risk factors warrant further study.

Aged↗

PubMed1996

Serial MRI in HIV Infection With and Without Neurologic Impairment.

To assess the relationship of longitudinal brain magnetic resonance imaging (MRI) and infection with human immunodeficiency virus (HIV), a cohort of HIV+ and HIV− gay men and injection drug users (IDU) were evaluated prospectively. Subjects underwent two evaluations including MRI scans, neurologic examinations, neuropsychological assessments and lymphocyte subset determinations one year apart. MRI changes over a one year period were analyzed with respect to serostatus, risk group, CD4 counts, neurological findings and neuropsychological performance. The frequency of MRI changes was no different in subjects with or without HIV infection and no new opportunistic infections or neoplasms were seen. However, among HIV+ subjects with CD4 count < 200 at the time of the initial scan, an increase in white matter hyperintensities was significantly more common. Also among HIV+ subjects, atrophy increased in association with declining CD4 count. Finally, subjects who developed significant neurologic deterioration in one year were much more likely to have increased atrophy. These results suggest that while there are morphological brain changes associated with HIV infection, they are most often seen in association with immunologic or neurologic deterioration.

Atrophy↗

PubMed1996

Relative risk of Alzheimer disease and age-at-onset distributions, based on APOE genotypes among elderly African Americans, Caucasians, and Hispanics in New York City.

Apolipoprotein-E epsilon 4 (APOE-epsilon 4) has been consistently associated with Alzheimer disease (AD) and may be responsible for an earlier age at onset. We have previously reported a diminished association between APOE-epsilon 4 and AD in African Americans. Using a new method, which allows inclusion of censored information, we compared relative risks by APOE genotypes in an expanded collection of cases and controls from three ethnic groups in a New York community. The relative risk for AD associated with APOE-epsilon 4 homozygosity was increased in all ethnic groups (African American relative risk [RR]=3.0; 95% confidence interval [CI]=1.5-5.9; Caucasian RR=7.3, 95% CI=2.5-21.6; and Hispanic RR=2.5, 95% CI=1.1-5.7), compared with those with APOE-epsilon 3/epsilon 3 genotypes. The risk was also increased for APOE-epsilon 4 heterozygous Caucasians (RR=2.9, 95% CI=1.7-5.1) and Hispanics (RR=1.6, 95% CI=1.1-2.3), but not for African Americans (RR=0.6, 95% Ci=0.4-0.9). The age distribution of the proportion of Caucasians and Hispanics without AD was consistently lower for APOE-epsilon 4 homozygous and APOE-epsilon 4 heterozygous individuals than for those with other APOE genotypes. In African Americans this relationship was observed only in APOE-epsilon 4 homozygotes. These results confirm that APOE genotypes influence the RR of AD in Caucasians and Hispanics. Differences in risk among APOE-epsilon 4 heterozygote African Americans suggest that other genetic or environmental factors may modify the effect of APOE-epsilon 4 in some populations.

Age of Onset↗

PubMed1995

Linear rank tests for doubly censored data.

This paper establishes the asymptotic properties of the non-parametric maximum likelihood estimator of the survival function based on data censored both from the left and the right. We show that the sample mean based on the survival estimator converges to a normal distribution, and we derive non-parametric tests for the differences in survival functions. The methods are applied to a study of dementia associated with Parkinson's disease.

Adult↗

PubMed1995

The frequency of idiopathic Parkinson's disease by age, ethnic group, and sex in northern Manhattan, 1988-1993.

Sex and ethnic differences in the frequency of Parkinson's disease have become increasingly important, because putative genetic and environmental risk factors have been identified. The authors estimated the prevalence and incidence of Parkinson's disease in a culturally diverse community in New York City over a 4-year period (January 1, 1988-December 31, 1991) using a disease registry substantiated, for older individuals, by a subsequent survey of a random sample of Medicare recipients between January 1, 1992, and December 31, 1993. The prevalence rate was 107 per 100,000 persons, and over a 3-year period the average incidence rate was 13 per 100,000 person-years. Age-adjusted prevalence rates were lower for women than for men in each ethnic group and were lower for blacks than for whites and Hispanics. Incidence rates were highest among black men, but they were otherwise comparable across the sex and ethnic groups. The estimated cumulative incidence of Parkinson's disease up to age 90 years was lower for women than for men, which could partially explain the lower prevalence rate. By ethnic group, the cumulative incidence was higher for blacks than for whites and Hispanics, but more deaths occurred among incident black cases. Discrepant prevalence and incidence rates of Parkinson's disease among blacks and women warrant further investigation. While selective mortality could partially account for this paradox, it is also possible that a delay in diagnosis due to limited access to appropriate health services among these individuals could have resulted in the observed discordant rates of disease.

Age Distribution↗

PubMed1995

The frequency and associated risk factors for dementia in patients with Parkinson's disease.

OBJECTIVES: To estimate the frequency and determine the risk factors for incident dementia in community-dwelling patients with Parkinson's disease (PD) and in control subjects. DESIGN: Prospective cohort study. During a 3.5-year period, 140 patients with idiopathic PD without evidence of dementia and 572 nondemented control subjects were identified in the community of Washington Heights-Inwood in New York, NY. All subjects underwent neurological and neuropsychological evaluations and follow-up examinations. RESULTS: Twenty-seven patients with PD (19.2%) became demented throughout 2 years, as compared with 87 (15.2%) of the control subjects. The relative risk (RR) for the development of dementia with PD was 1.7 (95% confidence interval [CI], 1.1 to 2.7) after adjusting for age, education, and gender. Predictive features of incident dementia were an extrapyramidal score greater than 25 (RR, 3.56; 95% CI, 1.4 to 8.9) and a Hamilton Depression Rating Scale score greater than 10 (RR, 3.55; 95% CI, 1.6 to 7.9). CONCLUSION: Patients with PD, especially those with severe extrapyramidal signs, have almost twice the risk for the development of dementia than do community-dwelling control subjects.

Aged↗

PubMed1995

Differences in the prevalence of essential tremor among elderly African Americans, whites, and Hispanics in northern Manhattan, NY.

BACKGROUND: Until now there has been only one community-based study to examine interethnic differences in the prevalence of essential tremor (ET). The study suggested a higher prevalence among whites than African Americans. The present study is the first to examine differences in the prevalence of ET among Hispanics, African Americans, and whites. OBJECTIVE: To estimate the prevalence of essential tremor (ET) in a cohort of community-dwelling elderly of mixed ethnic background. METHODS: A random sample of 2117 Medicare recipients residing in Washington Heights-Inwood in northern Manhattan, NY, were interviewed. A standardized neurological assessment was performed on those who had neurological complaints and on a random sample of those who did not. Essential tremor was defined as a postural or kinetic tremor of the head or limbs. Diagnoses were independently confirmed by two neurologists based on videotaped examination. RESULTS: After age adjustment to the 1990 Washington Heights-Inwood census, the prevalence of ET was 40.2 per 1000 (95% confidence interval, 31.8 to 48.6). Among 46 cases with ET, ET was significantly more prevalent in men than in women (chi 2 = 5.0, P = .03). Prevalence increased significantly with age. The prevalence was higher in whites than African Americans. The prevalence in Hispanics was intermediate. CONCLUSION: The prevalence of ET increases with age and may be higher among men and whites. Prospective studies are needed to further examine these associations.

Black or African American↗

PubMed1995

Apolipoprotein E and Alzheimer's disease: ethnic variation in genotypic risks.

The presence of the apolipoprotein epsilon 4 (apo epsilon 4) allele significantly increases the risk of Alzheimer's disease. Whether this is due to biological effects of the apo epsilon 4 protein or reflects linkage disequilibrium with an as yet unidentified Alzheimer's disease susceptibility gene is of critical importance. In a community study in northern Manhattan we found a fivefold increase in the risk of Alzheimer's disease among African-Americans, Hispanics, and whites homozygous for apo epsilon 4. Overall, the risk between Alzheimer's disease and apo epsilon 4 heterozygosity was also increased by twofold, but the association was somewhat weaker for African-Americans than for Hispanics and whites. In contrast, the apo epsilon 2/epsilon 3 genotype was associated with an eightfold increased risk of Alzheimer's disease in African-Americans but it was associated with reduced risk in whites. Variability in the strength and type of association between Alzheimer's disease and the apo E polymorphisms in the three ethnic groups could not be fully explained by age differences. The allelic frequency of apo epsilon *4 was significantly higher in patients than control subjects in all ethnic groups at age 70 or younger, reflecting the higher proportion of apo epsilon 4 homozygotes, but this difference diminished with increasing age. The allelic frequency of apo epsilon *2 for African-Americans and Hispanics, but not whites, was significantly higher in patients than control subjects, but only after age 70.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1995

Increased risk of mortality in Alzheimer's disease patients with more advanced educational and occupational attainment.

A reserve hypothesis suggests that clinical symptoms of Alzheimer's disease (AD) begin earlier in individuals with less education. Therefore, patients with less education might survive longer after diagnosis than those with more education. Two hundred forty-six subjects with probable AD were followed for 1 to 4 years. There were 78 deaths; 30 deaths occurred in the 127 patients whose education was < or = 8 years, while 48 deaths occurred in the 119 patients with > 8 years of education. Cox proportional hazards models adjusted for age, gender, and clinical dementia rating (CDR) showed that patients with more education had increased mortality (continuous variable: RR = 1.06 for each year of education; 95% confidence interval [CI], 1.01-1.11; dichotomous variable at 8 yr: RR = 1.76; CI, 1.11-2.77). This observation might at first seem counterintuitive, since groups with lower socioeconomic status are often at greater mortality risk. It implies that at any level of assessed clinical severity, the underlying pathology of AD is more advanced in patients with more education, resulting in shorter duration of diagnosed disease before death. These findings suggest either that education systematically influences global ratings of disease severity or that education provides a reserve against the clinical manifestation of AD pathology.

Aged↗

PubMed1995

Synergistic effects of traumatic head injury and apolipoprotein-epsilon 4 in patients with Alzheimer's disease.

The apolipoprotein-epsilon 4 allele increases the risk of Alzheimer's disease (AD), but cerebral deposition of beta-amyloid with age, a genetic mutation, or head injury may contribute to the pathogenesis of this disease. We examined the risks of AD associated with traumatic head injury and apolipoprotein-epsilon 4 in 236 community-dwelling elderly persons. A 10-fold increase in the risk of AD was associated with both apolipoprotein-epsilon 4 and a history of traumatic head injury, compared with a two-fold increase in risk with apolipoprotein-epsilon 4 alone. Head injury in the absence of an apolipoprotein-epsilon 4 allele did not increase risk. These data imply that the biological effects of head injury may increase the risk of AD, but only through a synergistic relationship with apolipoprotein-epsilon 4.

Aged↗

PubMed1994

Influence of education and occupation on the incidence of Alzheimer's disease.

OBJECTIVE: Several cross-sectional studies have found an association between Alzheimer's disease (AD) and limited educational experience. It has been difficult to establish whether educational experience is a risk factor for AD because educational attainment can influence performance on diagnostic tests. This study was designed to determine whether limited educational level and occupational attainment are risk factors for incident dementia. DESIGN: Cohort incidence study. SETTING: General community. PARTICIPANTS: A total of 593 nondemented individuals aged 60 years or older who were listed in a registry of individuals at risk for dementia in North Manhattan, NY, were identified and followed up. INTERVENTIONS: We reexamined subjects 1 to 4 years later with the identical standardized neurological and neuropsychological measures. MAIN OUTCOME MEASURES: Incident dementia. RESULTS: We used Cox proportional hazards models, adjusting for age and gender, to estimate the relative risk (RR) of incident dementia associated with low educational and occupational attainment. Of the 593 subjects, 106 became demented; all but five of these met research criteria for AD. The risk of dementia was increased in subjects with either low education (RR, 2.02; 95% confidence interval [Cl], 1.33 to 3.06) or low lifetime occupational attainment (RR, 2.25; 95% Cl, 1.32 to 3.84). Risk was greatest for subjects with both low education and low life-time occupational attainment (RR, 2.87; 95% Cl, 1.32 to 3.84). CONCLUSIONS: The data suggest that increased educational and occupational attainment may reduce the risk of incident AD, either by decreasing ease of clinical detection of AD or by imparting a reserve that delays the onset of clinical manifestations.

Aged↗

PubMed1994

Smoking and Parkinson's disease.

Smoking was examined in relation to Parkinson's disease (PD) in a population-based study in northern Manhattan (New York City) because of its putative "protective effect." Using a case-control design, information on smoking and associated behaviors was obtained in structured interviews after standard diagnostic evaluations in both cases and controls. The overall prevalence of smoking in the population was 43.7%, decreasing to 37% after age 85. Smoking was most frequent in men, Blacks, and in both cases and controls using alcohol once per week or more. Cases had quit smoking more often than controls (87 vs. 64%), and had smoked for significantly fewer years (31 vs. 41 yrs; p < 0.05 for both). The age-at-onset for smokers with PD was similar to age-at-onset for nonsmokers with PD. The odds ratio (OR) for a history of smoking associated with PD was 1.1 (95% CI 0.7-1.8). No protective gradient was associated with heavier smoking patterns. However, the odds that patients with PD were still smoking at the time of the interview were significantly less than those for controls (OR = 0.2; 95% CI 0.1-0.5). These results do not support the hypothesis that smoking protects against PD; rather they strongly imply the converse, that PD reduces smoking.

Aged↗

PubMed1994

Utility of extrapyramidal signs and psychosis as predictors of cognitive and functional decline, nursing home admission, and death in Alzheimer's disease: prospective analyses from the Predictors Study.

OBJECTIVE: To examine whether either extrapyramidal signs or psychotic features are associated with more rapid progression of Alzheimer's disease. BACKGROUND: It has been unclear whether extrapyramidal signs and psychosis are predictors of faster course or are simply late signs. METHODS: Two hundred thirty-six patients with mild Alzheimer's disease were recruited in three cities and followed semiannually. RESULTS: Using Cox proportional hazards models that adjusted for age, sex, disease severity, and estimated duration of illness at study entry, the presence of extrapyramidal signs at entry was associated with higher relative risk (RR) of reaching moderate cognitive (RR = 2.35, 95% CI = 1.12 to 4.92) or functional (RR = 2.31, 95% CI = 1.37 to 3.90) severity, nursing home entry (RR = 2.51, 95% CI = 1.32 to 4.76), or death (RR = 3.04, 95% CI = 1.31 to 7.05). Psychosis predicted only the functional end point (RR = 1.85, 95% CI = 1.18 to 2.90). Using regression models, modified Mini-Mental State scores declined 1.30 points (95% CI = 0.16 to 2.44) per 6-month interval, more among patients with than those without extrapyramidal signs; patients with psychosis declined 1.15 (95% CI = 0.52 to 1.77) more mMMS points per interval. CONCLUSIONS: This study confirms extrapyramidal signs and psychosis as robust predictors of disease end points and rapid progression in Alzheimer's disease.

Age Factors↗