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The Argentina-Alzheimer's disease neuroimaging initiative (Arg-ADNI) study is a longitudinal prospective cohort of 50 participants at a single institution in Buenos Aires, Argentina. Longitudinal assessments on a neuropsychological test battery were performed on 15 controls, 24 mild cognitive impairment (MCI) patients and 12 Alzheimer's disease (AD) dementia patients. In our study population, there was a high prevalence of positive AD biomarkers in the AD group, 92.3% (12/13); and a low prevalence in the normal controls, 20%; almost half (48%) of the patients diagnosed with MCI had positive amyloid detection. After a one year, the significant differences found at baseline on neuropsychological testing were similar at the follow-up assessment even though the AD group had significantly altered its functional performance (FAQ and CDR). The exception was semantic fluency, which showed greater impairment between the AD group and MCI and normal controls respectively. For these tests, the addition of AD biomarkers as a variable did not significantly alter the variations previously found for the established clinical group's model. Finally, the one-year conversion rate to dementia was 20% in the MCI cohort. RESUMO El estudio de Argentina-Alzheimer's Disease Neuroimaging Initiative (Arg-ADNI) es una cohorte prospectiva de 50 pacientes seguidos en una misma institución. Fueron evaluados cognitivamente 15 controles normales (CN), 24 sujetos con deterioro cognitivo leve (DCL) y 12 con demencia tipo Alzheimer (DTA) leve. En los DTA, 92,3% tuvieron biomarcadores positivos para Alzheimer y 20% en los CN. Casi la mitad de los DCL presentaron biomarcadores positivos. Después de un año de seguimiento, la diferencias significativas halladas en la visita de inicio en las pruebas cognitivas fueron similares al año aunque los DTA tuvieron empeoramiento funcional medido en el FAQ y CDR. La excepción fue la fluencia semántica, la cual mostró mayor declinación entre DTA y los demás grupos. La incorporación de los biomarcadores como variable no alteró significativamente los hallazgos de grupo. La tasa de conversión a demencia anual fue del 20%.

Most studies on craniofacial morphology have focused on adult individuals, but patterns of variation are the outcome of genetic and epigenetic variables that interact throughout ontogeny. Among cranial regions, the orbits exhibit morphological variation and occupy an intermediate position between neurocranial and facial structures. The main objective of this work was to analyze postnatal ontogenetic variation and covariation in the morphology of the orbital region in a cross‐sectional series of humans from 0 to 31 years old. Landmarks and semilandmarks were digitized on the orbital rim, as well as in neighboring neural and facial structures. Data were analyzed using geometric morphometrics. Results indicated that orbital size increases during the first years of postnatal life, while the shape of the orbital aperture does not change significantly with age. In general, the pattern and magnitude of shape covariation do not vary markedly during postnatal life although some subtle shifts were documented. Additionally, the shape of the orbital aperture is more related to the anterior neurocranium than to zygomatic structures, even when the allometry is adjusted. Although we expected some influence from postnatal craniofacial growth and from some functional factors, such as mastication, on the development of the orbits, this assumption was not completely supported by our results. As a whole, our findings are in line with the prediction of an early influence of the eyes and extraocular tissues on orbital morphology, and could be interpreted in relation to processes promoting early neural development that coordinately affects orbital traits and the neurocranial skeleton. Fil: Barbeito Andrés, Jimena. Universidad Nacional de La Plata. Facultad de Cienicas Naturales y Museo. División Antropología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Anzelmo, Marisol. Universidad Nacional de La Plata. Facultad de Cienicas Naturales y Museo. División Antropología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Ventrice, Fernando. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; Argentina Fil: Pucciarelli, Hector Mario. Universidad Nacional de La Plata. Facultad de Cienicas Naturales y Museo. División Antropología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Sardi, Marina Laura. Universidad Nacional de La Plata. Facultad de Cienicas Naturales y Museo. División Antropología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Objectives This work assesses cranial vault thickness (CVT) ontogenetic changes using a computed tomography database to register thickness across multiple regions. Methods Vault images of 143 individuals from 0 to 31 years old were analyzed by thickness semiautomatic measurements. For each individual, we obtained a thickness mean measure (TMM) and its coefficient of variation, a measure of endocranial volume (EV), the distribution of relative frequencies of thickness—relative frequency polygon, and a topographic mapping that shows the thickness arrangement through a chromatic scale. Ontogenetic changes of these variables were evaluated by different regression models (TMM vs. age, EV vs. age, TMM vs. EV) and visual comparisons between the age groups. Results TMM increased during ontogeny until the onset of adulthood without sex differences, but the most accelerated growth rates occur during the first 6 years of postnatal life. TMM variations were associated with EV only in infants and children, but not in later periods. The polygons showed a flattening during ontogeny, probably due to an increase in thickness variation within individuals. However, the adult pattern of thickness arrangement, with the lateral region thinner than the regions near sagittal plane, was detected from infancy. Conclusion The pattern of thickness arrangement is established early in ontogeny but CVT increases and changes in distribution until adolescence. Several factors may influence CVT, such as the brain, muscles, vessels, and sutures. Fil: Anzelmo, Marisol. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Cienicas Naturales y Museo. División Antropología; Argentina Fil: Ventrice, Fernando. Fundación para la Lucha Contra las Enfermedades Neurológicas de la Infancia. Instituto de Investigaciones Neurológicas "Raúl Carrea"; Argentina Fil: Barbeito Andrés, Jimena. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Cienicas Naturales y Museo. División Antropología; Argentina Fil: Pucciarelli, Hector Mario. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Cienicas Naturales y Museo. División Antropología; Argentina Fil: Sardi, Marina Laura. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Cienicas Naturales y Museo. División Antropología; Argentina

The skull is considered a modular structure in which different parts are influenced by different factors and, as a result, achieve adult shape at different ages. Previous studies have suggested that the basicranium presents a modular pattern that distinguishes sagittal and lateral parts, probably affected by the brain and masticatory structures, respectively. The vault of modern humans, in contrast, has been considered as a highly integrated system mainly influenced by brain growth. Here, we explored developmental shape variation in sagittal and lateral ectocranial vault in humans in order to assess if both regions are ontogenetically dissociated. We used a sample of 135 cranial computed tomography images from 0 to 31 ages. Landmarks and semilandmarks were collected on sagittal and lateral regions and geometric morphometric techniques were applied separately for each region. On the shape coordinates, we used Goodall's F-test in order to assess the age when the adult configuration is attained. Principal component analysis enabled us to evaluate shape variation during ontogeny. Results indicated that both sagittal and lateral structures attain adult shape at early adolescence. Both regions express coordinated shape modifications probably due to shared developmental factors. It is concluded that masticatory muscles may not exert a strong enough influence to produce independent variation in the lateral traits. Thus, it is likely that the brain integrates sagittal and lateral parts of the vault across human ontogeny. Fil: Anzelmo, Marisol. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Cienicas Naturales y Museo. División Antropología; Argentina Fil: Barbeito Andrés, Jimena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Cienicas Naturales y Museo. División Antropología; Argentina Fil: Ventrice, Fernando. Fundación para la Lucha Contra las Enfermedades Neurológicas de la Infancia. Instituto de Investigaciones Neurológicas "Raúl Carrea"; Argentina Fil: Pucciarelli, Hector Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Cienicas Naturales y Museo. División Antropología; Argentina Fil: Sardi, Marina Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Cienicas Naturales y Museo. División Antropología; Argentina

La canalización es una propiedad del desarrollo que pone límite y dirección a la variación morfológica y puede expresarse como una reducción de la varianza entre individuos. El objetivo de este trabajo es evaluar la varianza de tamaño y forma del cráneo humano durante la ontogenia postnatal a fin de inferir canalización. Se relevaron puntos craneométricos sobre 266 cráneos de individuos con edades de muerte de 0, 2, 7, 12, 15, 18 y 20 años. Mediante técnicas de morfometría geométrica, se calcularon para cada edad las varianzas del tamaño del centroide y de las coordenadas de forma y luego se compararon las varianzas de edades sucesivas. La varianza de forma y tamaño no presenta un patrón de disminución progresiva durante la ontogenia. Entre las sucesivas edades no hay diferencias significativas de la varianza de tamaño, pero se registraron reducciones significativas de la varianza de forma entre los grupos de 0 y 2 años para el neurocráneo y entre los 7 y 12 años para el esplacnocráneo. Esto sugiere que la canalización se relaciona con eventos del desarrollo como el crecimiento del cerebro y la emergencia dentaria que afectan diferencialmente al neurocráneo y al esplacnocráneo en momentos particulares de la ontogenia., Canalization is a developmental property of organisms that constrains morphological variation and can be expressed as a reduction of the variance among individuals. This work aims to evaluate variance of size and shape in the human skull during postnatal ontogeny in order to infer canalization. Craniometric landmarks were digitized on 266 skulls of individuals at age 0, 2, 7, 12, 15, 18 and 20 years. Geometric morphometric was used to compute variance of size and shape at each age and then variances were compared between consecutive ages. Neither variance of size nor variance of shape showed progressive reduction along ontogeny. There were no differences in the variance of size between consecutives ages but significant reductions of variance of shape were found between ages 0 and 2 for the neurocranium, as well as between 7 and 12 for the face. These results suggest that canalization is related to developmental processes such as brain growth and dental emergency that affect differently the neurocranium and the face at particular moments of the ontogeny., Sociedad de Ciencias Morfológicas de La Plata

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