Inflammatory agents partially explain associations between cortical thickness, surface area, and body mass in adolescents and young adulthood.

BACKGROUND/OBJECTIVES: Excessive body mass index (BMI) has been linked to a low-grade chronic inflammation state. Unhealthy BMI has also been related to neuroanatomical changes in adults. Research in adolescents is relatively limited and has produced conflicting results. This study aims to address the relationship between BMI and adolescents' brain structure as well as to test the role that inflammatory adipose-related agents might have over this putative link. METHODS: We studied structural MRI and serum levels of interleukin-6, tumor necrosis factor alpha (TNF-α), C-reactive protein and fibrinogen in 65 adolescents (aged 12-21 years). Relationships between BMI, cortical thickness and surface area were tested with a vertex-wise analysis. Subsequently, we used backward multiple linear regression models to explore the influence of inflammatory parameters in each brain-altered area. RESULTS: We found a negative association between cortical thickness and BMI in the left lateral occipital cortex (LOC) and the right precentral gyrus as well as a positive relationship between surface area and BMI in the left rostral middle frontal gyrus and the right superior frontal gyrus. In addition, we found that higher fibrinogen serum concentrations were related to thinning within the left LOC (ß = -0.45, p < 0.001), while higher serum levels of TNF-α were associated to a greater surface area in the right superior frontal gyrus (ß = 0.32, p = 0.045). Besides, we have also identified a trend that negatively correlates the cortical thickness of the left fusiform gyrus with the increases in BMI. It was also associated to fibrinogen (ß = -0.33, p = 0.035). CONCLUSIONS: These results suggest that adolescents' body mass increases are related with brain abnormalities in areas that could play a relevant role in some aspects of feeding behavior. Likewise, we have evidenced that these cortical changes were partially explained by inflammatory agents such as fibrinogen and TNF-α.

Allostatic load and executive functions in overweight adults.

BACKGROUND/OBJECTIVE: Overweight is linked to inflammatory and neuroendocrine responses potentially prompting deregulations in biological systems harmful to the brain, particularly to the prefrontal cortex. This structure is crucial for executive performance, ultimately supervising behaviour. Thus, in the present work, we aimed to test the relationship between allostatic load increase, a surrogate of chronic physiological stress, and core executive functions, such as cognitive flexibility, inhibitory control, and working memory. METHOD: Forty-seven healthy-weight and 56 overweight volunteers aged from 21 to 40 underwent medical and neuropsychological examination. RESULTS: Overweight subjects exhibited a greater allostatic load index than healthy-weight individuals. Moreover, the allostatic load index was negatively related to inhibitory control. When separated, the link between allostatic load index and cognitive flexibility was more marked in the overweight group. CONCLUSIONS: An overweight status was linked to chronic physiological stress. The inverse relationship between the allostatic load index and cognitive flexibility proved stronger in this group. Set-shifting alterations could sustain rigid-like behaviours and attitudes towards food.

Allostatic load and disordered white matter microstructure in overweight adults.

Overweight and stress are both related to brain structural abnormalities. The allostatic load model states that frequent disruption of homeostasis is inherently linked to oxidative stress and inflammatory responses that in turn can damage the brain. However, the effects of the allostatic load on the central nervous system remain largely unknown. The current study aimed to assess the relationship between the allostatic load and the composition of whole-brain white matter tracts in overweight subjects. Additionally, we have also tested for grey matter changes regarding allostatic load increase. Thirty-one overweight-to-obese adults and 21 lean controls participated in the study. Our results showed that overweight participants presented higher allostatic load indexes. Such increases correlated with lower fractional anisotropy in the inferior fronto-occipital fasciculi and the right anterior corona radiata, as well as with grey matter reductions in the left precentral gyrus, the left lateral occipital gyrus, and the right pars opercularis. These results suggest that an otherwise healthy overweight status is linked to long-term biological changes potentially harmful to the brain.

Cerebral networks of sustained attention and working memory: a functional magnetic resonance imaging study based on the Continuous Performance Test.

INTRODUCTION: One of the most used paradigms in the study of attention is the Continuous Performance Test (CPT). The identical pairs version (CPT-IP) has been widely used to evaluate attention deficits in developmental, neurological and psychiatric disorders. However, the specific locations and the relative distribution of brain activation in networks identified with functional imaging, varies significantly with differences in task design. AIM: To design a task to evaluate sustained attention using functional magnetic resonance imaging (fMRI), and thus to provide data for research concerned with the role of these functions. SUBJECTS AND METHODS: Forty right-handed, healthy students (50% women; age range: 18-25 years) were recruited. A CPT-IP implemented as a block design was used to assess sustained attention during the fMRI session. RESULTS: The behavioural results from the CPT-IP task showed a good performance in all subjects, higher than 80% of hits. fMRI results showed that the used CPT-IP task activates a network of frontal, parietal and occipital areas, and that these are related to executive and attentional functions. CONCLUSIONS: In relation to the use of the CPT to study of attention and working memory, this task provides normative data in healthy adults, and it could be useful to evaluate disorders which have attentional and working memory deficits.

TITLE: Bases cerebrales de la atencion sostenida y la memoria de trabajo: un estudio de resonancia magnetica funcional basado en el Continuous Performance Test.Introduccion. Uno de los paradigmas mas utilizados en el estudio de la atencion es el Continuous Performance Test (CPT). La version de pares identicos (CPT-IP) se ha utilizado ampliamente para evaluar los deficits de atencion en los trastornos del neurodesarrollo, neurologicos y psiquiatricos. Sin embargo, la localizacion de la activacion cerebral de las redes atencionales varia significativamente segun el diseño de resonancia magnetica funcional (RMf) usado. Objetivo. Diseñar una tarea para evaluar la atencion sostenida y la memoria de trabajo mediante RMf para proporcionar datos de investigacion relacionados con la localizacion y el papel de estas funciones. Sujetos y metodos. El estudio conto con la participacion de 40 estudiantes, todos ellos diestros (50%, mujeres; rango: 18-25 años). La tarea de CPT-IP se diseño como una tarea de bloques, en la que se combinaban los periodos CPT-IP con los de reposo. Resultados. La tarea de CPT-IP utilizada activa una red formada por regiones frontales, parietales y occipitales, y estas se relacionan con funciones ejecutivas y atencionales. Conclusiones. La tarea de CPT-IP utilizada en nuestro trabajo proporciona datos normativos en adultos sanos para el estudio del sustrato neural de la atencion sostenida y la memoria de trabajo. Estos datos podrian ser utiles para evaluar trastornos que cursan con deficits en memoria de trabajo y en atencion sostenida.

Differential cerebral and neuropsychological consequences in dizygotic twins with prenatal alcohol exposure.

AIM: To relate structural and functional findings in one adolescent dizygotic twin pair with prenatal alcohol exposure. METHOD: Neuropsychological and volumetric magnetic resonance studies were carried out on a 13-year-old preterm dizygotic twin pair with prenatal alcohol exposure. RESULTS: Neuropsychological and brain structural findings differed between the twins. The child with the more affected phenotype had large-scale cognitive deficits and presented significant atrophy in several brain structures. Both subjects had white matter volume reductions relative to the whole cerebral volume. CONCLUSION: The neuropsychological and neuroimaging data reflect long-term consequences of prenatal alcohol exposure.