L. Gutiérrez

Prevalence and Incidence Rates of Dementia and Cognitive Impairment No Dementia in the Mexican Population: Data from the Mexican Health and Aging Study

Objective: To estimate the prevalence and incidence of dementia and cognitive impairment without dementia (CIND) in the Mexican population. Method: The MHAS study is a prospective panel study of health and aging in Mexico with 7,000 elders that represent eight million participants nationally. Using measurements of cognition and activities of daily living of dementia cases and CIND were identified at baseline and follow-up. Overall incidence rates and specific rates for sex, age, and education were calculated. Results: Prevalence was 6.1% and 28.7% for dementia and CIND, respectively. Incidence rates were 27.3 per 1,000 person-years for dementia and 223 per 1,000 persons-year for CIND. Rates of dementia and CIND increased with advancing age and decreased with higher educational level; sex had a differential effect depending on the age strata. Hypertension, diabetes, and depression were risk factors for dementia but not for CIND. Discussion: These data provide estimates of prevalence and incidence of dementia and cognitive impairment in the Mexican population for projection of future burden.

The Drosophila trithorax group gene tonalli (tna) interacts genetically with the Brahma remodeling complex and encodes an SP-RING finger protein.

The trithorax group genes are required for positive regulation of homeotic gene function. The trithorax group gene brahma encodes a SWI2/SNF2 family ATPase that is a catalytic subunit of the Brm chromatin-remodeling complex. We identified the tonalli (tna) gene in Drosophila by genetic interactions with brahma. tna mutations suppress Polycomb phenotypes and tna is required for the proper expressions of the Antennapedia, Ultrabithorax and Sex combs reduced homeotic genes. The tna gene encodes at least two proteins, a large isoform (TnaA) and a short isoform (TnaB). The TnaA protein has an SP-RING Zn finger, conserved in proteins from organisms ranging from yeast to human and thought to be involved in the sumoylation of protein substrates. Besides the SP-RING finger, the TnaA protein also has extended homology with other eukaryotic proteins, including human proteins. We show that tna mutations also interact with mutations in additional subunits of the Brm complex, with mutations in subunits of the Mediator complex, and with mutations of the SWI2/SNF2 family ATPase gene kismet. We propose that Tna is involved in postranslational modification of transcription complexes.

Cognition, functional status, education, and the diagnosis of dementia and mild cognitive impairment in Spanish-speaking elderly.

A group of 314 Spanish-speaking elders were classified in 55 participants with mild to moderate dementia, 74 participants with mild cognitive impairment (MCI), and 185 control participants, according to clinical evaluation derived. Sensitivity, specificity, and detection characteristics of frequently cognitive and functional tests were calculated in comparison with the clinical evaluation: Minimental State Examination, Brief Neuropsychological Test Battery, Short Blessed test, Pfeffer Functional Activities Questionnaire, and Blessed Dementia Scale. Influence of education on sensitivity and specificity values varied along the tests. For all the cognitive and functional measures, a great number of MCI participants who fulfilled Mayos (Mayos Clinical School) clinical criteria (Petersen et al., 1999) were misclassified as controls and a few were misclassified as demented. Level of education plays a very important role in both cognitive and functional assessment. The cognitive tests that are commonly used to screen demented patients may fail to detect MCI particularly in high-functioning individuals as well as those who are well educated.

Wannier-stark ladders in one-dimensional elastic systems.

The optical analogues of Bloch oscillations and their associated Wannier-Stark ladders have been recently analyzed. In this Letter we propose an elastic realization of these ladders, employing for this purpose the torsional vibrations of specially designed one-dimensional elastic systems. We have measured, for the first time, the ladder wave amplitudes, which are not directly accessible either in the quantum-mechanical or optical cases. The wave amplitudes are spatially localized and coincide rather well with theoretically predicted amplitudes. The rods we analyze can be used to localize different frequencies in different parts of the elastic systems and vice versa.

Locally periodic Timoshenko rod: experiment and theory.

The flexural vibrations of a locally periodic rod, which consists of N unit cells, are discussed both from the experimental and theoretical points of view. Timoshenkos beam theory and the transfer matrix method are used to calculate the normal-mode frequencies and amplitudes. The theoretical values are then compared with the experimental ones, which are obtained using an electromagnetic acoustic transducer (EMAT). Good agreement between the numerical results and the experimental measurements is obtained. It is shown that as N grows, a band spectrum emerges.

Compressional and torsional wave amplitudes in rods with periodic structures

To measure and detect elastic waves in metallic rods a low-frequency electromagnetic-acoustic transducer has been developed. Frequencies range from a few hertz up to hundreds of kilohertz. With appropriate configuration of the transducer, compressional or torsional waves can be selectively excited or detected. Although the transducer can be used in many different situations, it has been tested and applied to a locally periodic rod, which consists of a finite number of unit cells. The measured wave amplitudes are compared with theoretical ones, obtained with the one-dimensional transfer matrix method, and excellent agreement is obtained.

Doorway states in quasi–one-dimensional elastic systems

The doorway state phenomenon has been recently analysed in many different systems, both quantum and classical. The systems range from nuclei to sedimentary valleys, therefore covering a range in size of 19 orders of magnitude. It also applies to systems with chaotic spectra as well as to integrable systems. In all these works, the doorway state has been discussed only in the energy or frequency domains. In this letter we present numerical and experimental results for a quasi–one-dimensional elastic system which presents a doorway state and, for the first time, the temporal evolution of the phenomenon is measured directly.

Study of coupled resonators in analogous wave systems: Mechanical, elastic, and optical

Three classical systems formed by the pairs of coupled resonators are analyzed, including a system of elastically coupled masses, a system of rigid rods separated by a notch, and an optical system made by a pair of dielectric films separated by a thin metallic layer. We show numerically that these systems are analogous to each other. For the latter two systems, the theoretical results are confirmed experimentally. This study allows us to discuss in classical systems properties that typically are only described quantum mechanically, such as the avoided crossing theorem, the strength function phenomenon, and the effect of the coupling element.

Anderson localization in finite disordered vibrating rods

We study, both experimentally and numerically, the Anderson localization phenomenon in torsional waves of a disordered elastic rod, which consists of a cylinder with randomly spaced notches. We find that the normal-mode wave amplitudes are exponentially localized as occurs in disordered solids. The localization length, measured using these wave amplitudes, decreases as a function of frequency. The normal-mode spectrum is also measured as well as computed, so its level statistics can be analyzed. From the spectrum, the nearest-neighbor spacing distribution can be obtained. This distribution can be described by a phenomenological expression that depends on a parameter α, related to the level repulsion, which is also a function of the frequency. Therefore, the localization length can be expressed in terms of the parameter α. There exists a range in which the localization length grows linearly with α. However, at low values of this parameter the linear dependence does not hold.

Comparative Analysis of Cognitive Impairment Among Mexicans and Spanish-Speaking Immigrant’s Elders

Objectives: This study aims to compare the prevalence of cognitive impairment among older Mexicans and Spanish-speaking U.S. immigrants. Methods: The relationship of cognitive impairment with social and demographic variables was explored using data from five different population based survey studies. Results: Prevalence rates increased with age, with low educational level, didn’t show a clear association with gender and decreased in married subjects. Estimates of cognitive and functional impairment combined are greater in the immigrant samples than those for Mexican residents. Primary memory measures are the least discriminative for cognitive impairment, whereas orientation, attention, and secondary verbal memory measures discriminate better. Discussion: Mexicans and Spanish-speaking USA immigrants have similar prevalence estimates of cognitive impairment. However, prevalence of functional impairment differs between Mexicans and immigrants because of measurement issues and cultural factors.