Exportation and Validation of Latent Constructs for Dementia Case Finding in a Mexican American Population-based Cohort.

BACKGROUND: The latent variable "δ" has been validated as a dementia phenotype. δ can be extracted from Spearman's general intelligence factor "g" in any data set that contains measures of cognition and instrumental activities of daily living (IADL). We used δ composites ("d-scores") to estimate the prevalence of dementia in the Hispanic Established Population for Epidemiological Studies in the Elderly (H-EPESE). METHOD: δ was constructed from Mini-Mental State Examination, a clock-drawing task (CLOX), and IADL. δ's H-EPESE factor weights were validated in the well-characterized Texas Alzheimer's Research and Care Consortium (TARCC). Optimal thresholds for the discrimination between "Alzheimer's disease" (AD) versus normal controls (NCs) were determined by receiver operating characteristic curve. Those thresholds were used to estimate the prevalence of dementia in H-EPESE. RESULTS: Each δ homolog fits its source's data well. d-scores were strongly associated with Clinical Dementia Rating scale Sum of Boxes (r = .74-.85, all p < .001], and accurately distinguished AD cases from NCs, in both Mexican Americans (MAs) and non-Hispanic Whites (NHWs) [c = 0.94-0.96]. The TARCC MA threshold estimated the prevalence of dementia at 21.4% in H-EPESE. The NHW threshold estimated the prevalence of dementia at 21.0%. CONCLUSIONS: It is possible to export δ composites from populations to well-characterized cohorts for validation.

Organic Compounds Detected in Deciduous Teeth: A Replication Study from Children with Autism in Two Samples.

Biological samples are an important part of investigating toxic exposures and disease outcomes. However, blood, urine, saliva, or hair can only reflect relatively recent exposures. Alternatively, deciduous teeth have served as a biomarker of early developmental exposure to heavy metals, but little has been done to assess organic toxic exposures such as pesticides, plastics, or medications. The purpose of our study was to determine if organic chemicals previously detected in a sample of typically developing children could be detected in teeth from a sample of children with autism. Eighty-three deciduous teeth from children with autism spectrum disorders (ASD) were chosen from our tooth repository. Organic compounds were assessed using liquid chromatography tandem mass spectrometry and gas chromatography methods. Consistent with a prior report from Camann et al., (2013), we have demonstrated that specific semivolatile organic chemicals relevant to autism etiology can be detected in deciduous teeth. This report provides evidence that teeth can be useful biomarkers of early life exposure for use in epidemiologic case-control studies seeking to identify differential unbiased exposures during development between those with and without specific disorders such as autism.

Neuropsychiatric symptoms in community-dwelling Mexican-Americans: results from the Hispanic Established Population for Epidemiological Study of the Elderly (HEPESE) study.

OBJECTIVE: The Neuropsychiatric Inventory (NPI) is a well-established measure of psychopathology and frequently used in dementia studies. Little is known about its psychometric characteristics at a population level, particularly among Hispanics. We report the frequency of NPI symptoms in a community-dwelling older Mexican-American (MA) population cohort and the degree of symptom-related distress experienced by participant informants. METHODS: Participants were 1079 MA age 80 years and over residing in five southwestern states who were administered the NPI as part of wave-7 of the Hispanic Established Population for Epidemiological Study of the Elderly (HEPESE) conducted from 2010 to 2011. RESULTS: Nine hundred twenty-five informants rated NPI domains. Prevalence of neuropsychiatric symptoms (NPS) varied by symptom domain and ranged from agitation/aggression (32%) to euphoria/elation (5%). The overall rate of behavioral disturbances was 62.7%. On the other hand, 37.3% of informants reported no NPS. A significant fraction of the informants reported distress from the mood disorder cluster of the scale. CONCLUSIONS: A large percentage (>60%) of community-dwelling older MA have one or more informant-reported NPS. These symptoms have diagnostic, prognostic, and therapeutic implications. Although neuropsychiatric disorders may be the initial clinical manifestation of dementia and often appear before cognitive alterations, the high frequency of these symptoms in the HEPESE cohort may reflect a high prevalence of these disorders among community-dwelling MA. The pattern we observed also suggests relatively advanced stages of dementia.

Validation of a latent construct for dementia case-finding in Mexican-Americans.

We have constructed a latent dementia proxy, "δ", and validated it in several datasets, including well characterized subjects participating in the Texas Alzheimer's Research and Care Consortium (TARCC) study. It may be possible to construct δ homologs from almost any ad hoc combination of cognitive and functional status measures. δ homologs may also be relatively immune to measurement error, including cultural, linguistic, or educational biases. These properties make factor scores derived from latent variables a potentially attractive solution for dementia case-finding in rural or minority populations. Here we have explored an alternative and briefer assessment by which to construct a δ homolog and validate the resulting latent variable (dMA) in Mexican-American (MA) TARCC subjects. dMA, composed of simple "bedside" dementia screening instruments, achieves Areas Under the Receiver Operative Curve that rival those of δ itself. Ethnicity has a small effect on dMA's performance. These results suggest that it may be possible to validly export dMA into other MA populations, or to export δ homolog factor scores from one population to another.

The role of physical activity and diabetes status as a moderator: functional disability among older Mexican Americans.

PURPOSE: we investigate the temporal association between the rate of change in physical function and the rate of change in disability across four comparison groups: Those with and without diabetes who report >30 min of physical activity per day, and those who report <30 min of physical activity per day. METHODS: six waves of longitudinal data from the Hispanic Established Population for Epidemiologic Studies of the Elderly were utilised. At baseline, there were a total of 3,050 elder participants aged 65 years old or greater. The longitudinal rates of change in disability and physical function were compared by the diabetes status (ever versus none) and the physical activity status (less than or greater than or equal to 30 min per day). RESULTS: disability and physical function data were analysed using a latent growth curve modelling approach adjusted for relevant demographic/health-related covariates. There were statistically significant longitudinal declines in physical function and disability (P < 0.001) in all groups. Most notable, the physical activity status was an important moderator. Those with >30 min of activity demonstrated better baseline function and less disability as well as better temporal trajectories than those reporting <30 min of physical activity per day. Comparisons between diabetes statuses within the same physical activity groups showed worse disability trajectories among those with diabetes. CONCLUSIONS: a longitudinal decline in physical function and disability is moderated most notably by physical activity. The diabetes status further moderates decline in function and disability over time. Increased physical activity appears to be protective of disability in general and may lessen the influence of diabetes-related disability in older Mexican Americans, particularly at the end of life.

Explaining low rates of autism among Hispanic schoolchildren in Texas.

In data from the Texas Educational Agency and the Health Resources and Services Administration, we found fewer autism diagnoses in school districts with higher percentages of Hispanic children. Our results are consistent with previous reports of autism rates 2 to 3 times as high among non-Hispanic Whites as among Hispanics. Socioeconomic factors failed to explain lower autism prevalence among Hispanic schoolchildren in Texas. These findings raise questions: Is autism underdiagnosed among Hispanics? Are there protective factors associated with Hispanic ethnicity?

Association between acculturation and structural assimilation and mini-mental state examination-assessed cognitive impairment in older Mexican Americans: findings from the San Antonio Longitudinal Study of Aging.

Older Mexican Americans (MAs) have consistently scored lower on the Folstein Mini-Mental State Examination (MMSE) than older European Americans (EAs). These lower scores may arise from factors other than those traditionally posited (age and education). Thus, this study examined the association between acculturation and structural assimilation and MMSE-assessed cognitive impairment, taking into account education, income, and other contextual factors. Subjects were participants in the San Antonio Longitudinal Study of Aging, a community-based study of chronic disease and functional status in 457 older MAs and 376 older EAs. Scales were used to measure two dimensions of acculturation: (family attitude, cultural values) and structural assimilation (functional integration into the broader American society). Logistic regression was used to examine the association between age, sex, acculturation, and structural assimilation and MMSE scores suggestive of cognitive impairment (<24). After adjusting for contextual factors (age, sex, education and household income), diseases (diabetes mellitus, stroke, and hypertension), and sensory impairments (hearing and vision), structural assimilation, but neither dimension of acculturation, was significantly and negatively associated with MMSE-assessed cognitive impairment. Older MAs in the lowest structural assimilation stratum were 1.89 times as likely to have MMSE-assessed cognitive impairment as those in the highest. Age, education, and visual impairment were also independently associated with cognitive impairment. These findings highlight the need for geriatricians to take contextual factors (including age, education, and structural assimilation) into account when interpreting MMSE scores of MA patients.

Association between change in systolic blood pressure and cognitive decline among elderly Mexican Americans: data from the Hispanic established population for epidemiology study of the elderly.

The longitudinal association between the rate of change in blood pressure and cognitive decline was examined in an area probability sample from a population-based survey of elderly Mexican Americans, 65 years of age or older obtained in 1993--1994, 1995--1996, 1998--1999, and 2000--2001 (n = 2859). The sample was divided into two groups at baseline: hypertensives had a systolic blood pressure (SBP) > or = 140 mm Hg, a diastolic blood pressure (DBP) > or = 90 mm Hg, or indicated a prior diagnosis of hypertension, and the normotensive group. Cognition was indexed by the Mini-Mental State Examination (MMSE). Neither SBP nor DBP at baseline predicted cognitive decline. However, the mean slope for SBP in the normotensive group showed an increase of 4.55mm Hg (increase from Time 1 to Time 2 was 123mm Hg to 132 mm Hg) and was significant in a regression model predicting cognitive decline even after adjusting for covariates. These findings suggest an association between increasing SBP and cognitive decline for normotensive elderly in this study population.

Prevalence and patterns of executive impairment in community dwelling Mexican Americans: results from the Hispanic EPESE Study.

INTRODUCTION: Little is known about the prevalence of impaired executive control function (ECF) in community dwelling elderly or minority populations. We have determined the prevalence of cognitive impairment and impaired ECF in a community dwelling Mexican American elderly population, and their associations with functional status. SUBJECTS: Subjects were 1165 Mexican Americans age 65 and over who were administered CLOX as part of the third wave of the Hispanic Established Population for Epidemiological Study (HEPESE) conducted from 1998 to 1999. METHODS: ECF was measured by an executive clock-drawing task (CDT) (i.e. CLOX1). Non-executive cognitive function was assessed by the Mini-Mental State Examination (MMSE) and a non-executive CDT (CLOX2). CLOX scores were combined to estimate the prevalence of global CLOX failure (i.e. 'Type 1' cognitive impairment) vs isolated CLOX1 failure (i.e. Type 2 cognitive impairment). RESULTS: 59.3% of subjects failed CLOX1. 31.1% failed both CLOX1 and CLOX2 (Type 1 cognitive impairment). 33.3% failed CLOX1 only (Type 2 cognitive impairment). 35.6% passed both measures [no cognitive impairment (NCI)]. Many subjects with CLOX1 impairment at Wave 3 had normal MMSE scores. This was more likely to occur in the context of Type 2 cognitive impairment. Both CLOX defined cognitive impairment groups were associated with functional impairment. CONCLUSIONS: A large percentage of community dwelling Mexican American elderly suffer cognitive impairment that can be demonstrated through a CDT. Isolated executive impairments appear to be most common. The ability of a CDT to demonstrate ECF impairments potentially offers a rapid, culturally unbiased and cost-effective means of assessing this domain. In contrast, the MMSE is relatively insensitive to ECF assessed by CLOX1.

Evaluation of the mini-mental state examination's internal consistency in a community-based sample of Mexican-American and European-American elders: results from the San Antonio Longitudinal Study of Aging.

This study examined the effect of scoring method, education, and language usage on internal consistency of the Folstein Mini-Mental State Examination (MMSE). Trained bilingual staff administered the MMSE in participants' homes as part of the San Antonio Longitudinal Study of Aging home-based assessment battery. Subjects included 833 community-dwelling Mexican-American (MA) and European-American (EA) elders, aged 65 and older, residing in three socioculturally distinct neighborhoods in San Antonio, Texas. Three methods of scoring the MMSE were examined: serial sevens only, spelling only, and serial sevens or spelling, whichever was higher. Mean MMSE scores+/-standard deviation ranged from 27.7+/-2.4 to 28.5+/-1.9 for EAs, from 25.6+/-3.2 to 27.2+/-2.9 for MAs interviewed in English, and from 22.5+/-4.5 to 25.5+/-3.5 for MAs interviewed in Spanish, depending on scoring method. Across the three ethnic-language subgroups, the lowest mean scores, largest coefficients of variation, and highest alpha coefficients were observed using serial sevens only. Stratification by educational level showed that alpha coefficients for all three scoring methods were consistently lower in high school graduates than in less-educated groups. Serial sevens only was the only scoring method that yielded acceptably high alpha coefficients across all ethnic, language, and education subgroups. Thus, clinicians should use the serial sevens-only method when administering the MMSE and be alert to the increased potential for false-negatives in more highly educated EA and MA elders, particularly in EAs and MAs proficient in English.