Mapping the neuroanatomy of functional decline in Alzheimer's disease from basic to advanced activities of daily living.

BACKGROUND: Impairments in activities of daily living (ADL) are a criterion for Alzheimer's disease (AD) dementia. However, ADL gradually decline in AD, impacting on advanced (a-ADL, complex interpersonal or social functioning), instrumental (IADL, maintaining life in community), and finally basic functions (BADL, activities related to physiological and self-maintenance needs). Information and communication technologies (ICT) have become an increasingly important aspect of daily functioning. Yet, the links of ADL, ICT, and neuropathology of AD dementia are poorly understood. Such knowledge is critical as it can provide biomarker evidence of functional decline in AD. METHODS: ADL were evaluated with the Technology-Activities of Daily Living Questionnaire (T-ADLQ) in 33 patients with AD and 30 controls. ADL were divided in BADL, IADL, and a-ADL. The three domain subscores were covaried against gray matter atrophy via voxel-based morphometry. RESULTS: Our results showed that three domain subscores of ADL correlate with several brain structures, with a varying degree of overlap between them. BADL score correlated mostly with frontal atrophy, IADL with more widespread frontal, temporal and occipital atrophy and a-ADL with occipital and temporal atrophy. Finally, ICT subscale was associated with atrophy in the precuneus. CONCLUSIONS: The association between ADL domains and neurodegeneration in AD follows a traceable neuropathological pathway which involves different neural networks. This the first evidence of ADL phenotypes in AD characterised by specific patterns of functional decline and well-defined neuropathological changes. The identification of such phenotypes can yield functional biomarkers for dementias such as AD.

Neuroanatomical Comparison of the "Word" and "Picture" Versions of the Free and Cued Selective Reminding Test in Alzheimer's Disease.

Episodic memory tests with cued recall, such as the Free and Cued Selective Reminding Test (FCSRT), allow for the delineation of hippocampal and prefrontal atrophy contributions to memory performance in Alzheimer's disease (AD). Both Word and Picture versions of the test exist but show different profiles, with the Picture version usually scoring higher across different cohorts. One possible explanation for this divergent performance between the different modality versions of the test might be that they rely on different sets of neural correlates. The current study explores this by contrasting the neural correlates of the Word and Picture versions of the FCSRT with voxel-based morphometry (VBM) in AD and healthy subjects. We predicted that the Picture version would be associated with different cortical regions than the Word version, which might be more hippocampal-centric. When comparing 35 AD patients and 34 controls, AD patients exhibited impairments on both versions of the FCSRT and both groups performed higher in the Picture version. A region of interest analysis based on prior work revealed significant correlations between free recall of either version with atrophy of the temporal pole and hippocampal regions. Thus, contrary to expectations, performance on both the Word and the Picture version of the FCSRT is associated with largely overlapping networks. Free recall is associated with hippocampal volume and might be properly considered as an indicator of hippocampal structural integrity.

Tau Platelets Correlate with Regional Brain Atrophy in Patients with Alzheimer's Disease.

BACKGROUND: Intracellular neurofibrillary tangles are part of the core pathology of Alzheimer's disease (AD), which are mainly composed of hyperphosphorylated tau protein. OBJECTIVES: The purpose of this study is to determine whether high molecular weight (HMW) or low molecular weight (LMW) tau protein levels, as well as the ratio HMW/LMW, present in platelets correlates with brain magnetic resonance imaging (MRI) structural changes in normal and cognitively impaired subjects. METHODS: We examined 53 AD patients and 37 cognitively normal subjects recruited from two Memory Clinics at the Universidad de Chile. Tau levels in platelets were determined by immunoreactivity and the MRI scans were analyzed using voxel-based morphometry in 41 AD patients. RESULTS: The HMW/LMW tau ratio was statistically different between controls and AD patients, and no associations were noted between HMW or LMW tau and MRI structures. In a multivariate analysis controlled for age and education level, the HMW/LMW tau ratio was associated with reduced volume in the left medial and right anterior cingulate gyri, right cerebellum, right thalamus (pulvinar), left frontal cortex, and right parahippocampal region. CONCLUSIONS: This exploratory study showed that HMW/LMW tau ratio is significantly higher in AD patients than control subjects, and that it is associated with specific brain regions atrophy. Determination of peripheral markers of AD pathology can help understanding the pathophysiology of neurodegeneration in AD.

El histograma de números TC y la optimización de la corriente de tubo en tomografía computada de cerebro / CT number histogram and the optimization of tube current in brain computed tomography

Optimizar la corriente del tubo de Rx en un sistema de tomografía permite disminuir la dosis al paciente y alargar la vida útil del tubo. Se describe una metodología basada en el histograma de los números de TC que permite lograr esta meta en forma simple y objetiva. Se describe su utilización en tomografía cerebral sin contraste y se especifican valores de corriente óptimos para el tomógrafo CTMax-40 de GE

Un protocolo de tomografía computada para el estudio rutinario del cerebro frente a un diagnóstico clínico de cefalea en estudio / A protocol of brain computed tomography as opposed to clinical diagnosis of headache

Cefalea en estudio es la indicación para una tomografía computada cerebral de mayor frecuencia (63 por ciento a 80 por ciento) en un centro de imagenología ambulatorio. Nuestro protocolo vigente para una tomografía computada cerebral con indicación clínica de Cefalea en Estudio es completar 2 series de 30 cortes cada una, sin y con contraste iónico. Se revisaron 531 estudios cerebrales consecutivos, ambulatorios, 354 de ellos cefaleas en estudio, y se realizaron los pacientes, sus condiciones técnicas y resultados diagnósticos radiológicos. Los datos respaldan modificar el protocolo a una serie sin contraste y una serie contrastada sólo complementaria a un hallazgo radiológico. Ello con una misma calidad diagnóstica y reducción importante de la dosis por radiación y reacciones adversas del medio contraste

Reacciones adversas por uso intravenoso de medios de contraste iónicos monómeros en tomografía computada / Adverse reactions by intravenous ion monomerics contrast media use in computarized tomography

Los medios de contraste iónicos monómeros son los de uso más frecuente en estudios contrastados intravenosos en tomografía computada. Se describen las reacciones adversas de dos productos comerciales en los cuales el átomo de hidrógeno se reemplazó exclusivamente por meglumina (sin sodio) y que se diferencian sólo en la molécula R3 (diatrizoato en uno y ioxitalamato en el otro). Del registro y análisis de dos series, de más de 600 pacientes cada una, se concluye que ambos productos son igualmente seguros (reacciones graves y medianas) pero estadísticamente diferentes (p<0.05) en la frecuencia de reacciones leves

Protección radiológica en instalaciones de radiodiagnóstico: un estudio de resultados en la rutina clínica / Radiologic protection in radiodiagnostic installations: study on clinical routine results

Se midió la tasa de exposición (mR/hora) en un promedio de 10 posiciones relevantes con un criterio de protección radiológica, en un total de 17 instalaciones de radiodiagnóstico (radiología osteoarticular, tomografía computada, mamografía, radiología digestiva y dental) de la red de centros médicos de OMESA y Clínica Santa María. Se calcularon las dosis acumuladas en un período de 1 semana, en condiciones de rutina clínica y operacionalmente conservadoras, y se comprobó que todas ellas son muy inferiores a los máximos permisibles y hacen innecesario el uso de barreras secundarias. La muestra es representativa de instalaciones similares en nuestro medio, lo cual permite extrapolar estos resultados a otras instalaciones