Mar Ariza

Hippocampal head atrophy after traumatic brain injury

Traumatic brain injury (TBI) causes hippocampal damage. The hippocampus can be macroscopically divided into the head, body and tail, which differ in terms of their sensitivity to excitability and also in terms of their cortical connections. We investigated whether damage also varies according to the hippocampal area involved, and studied the relationship of hippocampal reductions with memory performance. Twenty TBI patients and matched controls were examined. MRI measurements were performed separately for the hippocampal head, body and tail. Memory outcome was measured by Reys auditory verbal learning test, Reys complex figure test and a modified version of Warringtons facial recognition memory test. Group comparison showed that patients had bilateral hippocampal atrophy, mainly involving the hippocampal head. Moreover, TBI subjects showed verbal memory deficits which presented slight correlations with left hippocampal head atrophy.

Alterations of the salience network in obesity: A resting‐state fMRI study

Obesity is a major health problem in modern societies. It has been related to abnormal functional organization of brain networks believed to process homeostatic (internal) and/or salience (external) information. This study used resting‐state functional magnetic resonance imaging analysis to delineate possible functional changes in brain networks related to obesity. A group of 18 healthy adult participants with obesity were compared with a group of 16 lean participants while performing a resting‐state task, with the data being evaluated by independent component analysis. Participants also completed a neuropsychological assessment. Results showed that the functional connectivity strength of the putamen nucleus in the salience network was increased in the obese group. We speculate that this abnormal activation may contribute to overeating through an imbalance between autonomic processing and reward processing of food stimuli. A correlation was also observed in obesity between activation of the putamen nucleus in the salience network and mental slowness, which is consistent with the notion that basal ganglia circuits modulate rapid processing of information. Hum Brain Mapp 34:2786–2797, 2013.

Influence of APOE polymorphism on cognitive and behavioural outcome in moderate and severe traumatic brain injury

Aim: To analyse the influence of apolipoprotein (APOE) ε4 status on the cognitive and behavioural functions usually impaired after moderate and severe traumatic brain injury (TBI). Methods: In all, 77 patients with TBI selected from 140 consecutive admissions were genotyped for APOE. Each patient was subjected to neuropsychological and neurobehavioural assessment at least 6 months after injury. Results: Performance of participants carrying the ε4 allele was notably worse on verbal memory (Auditory Verbal Learning Test), motor speed, fine motor coordination, visual scanning, attention and mental flexibility (Grooved Pegboard, Symbol Digit Modalities Test and part B of the Trail Making Test) and showed considerably more neurobehavioural disturbances (Neurobehavioral Rating Scale—Revised) than the group without the ε4 allele. Conclusions: In particular, performance on neuropsychological tasks that are presumed to be related to temporal lobe, frontal lobe and white matter integrity is worse in patients with the APOE ε4 allele than in those without it. More neurobehavioural disturbances are observed in APOE ε4 carriers than in APOE ε2 and ε3 carriers.

Neural Responses to Visual Food Cues: Insights from Functional Magnetic Resonance Imaging

The aim of this paper is to describe the patterns of functional magnetic resonance imaging activation produced by visual food stimuli in healthy participants, as well as in those with anorexia nervosa, bulimia nervosa, binge eating disorder and obesity. We conducted a systematic review of studies published in the last decade on normal and abnormal eating. This review suggested the existence of neural differences in response to the sight of food between healthy individuals, those with an eating disorder and obese subjects. Differences were identified in two brain circuits: (i) limbic and paralimbic areas associated with salience and reward processes and (ii) prefrontal areas supporting cognitive control processes.

Frontal cortical thinning and subcortical volume reductions in early adulthood obesity

Obesity depends on homeostatic and hedonic food intake behavior, mediated by brain plasticity changes in cortical and subcortical structures. The aim of this study was to investigate cortical thickness and subcortical volumes of regions related to food intake behavior in a healthy young adult sample with obesity. Thirty-seven volunteers, 19 with obesity (age=33.7±5.7 (20-39) years body-mass index (BMI)=36.08±5.92 (30.10-49.69)kg/m(2)) and 18 controls (age=32.3±5.9 (21-40) years; BMI=22.54±1.94 (19.53-24.97)kg/m(2)) participated in the study. Patients with neuropsychiatric or biomedical disorders were excluded. We used FreeSurfer software to analyze structural magnetic resonance images (MRI) and obtain global brain measures, cortical thickness and subcortical volume estimations. Finally, correlation analyses were performed for brain structure data and obesity measures. There were no between-group differences in age, gender, intelligence or education. Results showed cortical thickness reductions in obesity in the left superior frontal and right medial orbitofrontal cortex. In addition, the obesity group had lower ventral diencephalon and brainstem volumes than controls, while there were no differences in any other subcortical structure. There were no statistically significant correlations between brain structure and obesity measures. Overall, our work provides evidence of the structural brain characteristics associated with metabolically normal obesity. We found reductions in cortical thickness, ventral diencephalon and brainstem volumes in areas that have been implicated in food intake behavior.

Dopamine Genes (DRD2/ANKK1-TaqA1 and DRD4-7R) and Executive Function: Their Interaction with Obesity

Obesity is a multifactorial disease caused by the interaction between genotype and environment, and it is considered to be a type of addictive alteration. The A1 allele of the DRD2/ANKK1-TaqIA gene has been associated with addictive disorders, with obesity and with the performance in executive functions. The 7 repeat allele of the DRD4 gene has likewise been associated with the performance in executive functions, as well as with addictive behaviors and impulsivity. Participants were included in the obesity group (N = 42) if their body mass index (BMI) was equal to or above 30, and in the lean group (N = 42) if their BMI was below 25. The DRD2/ANKK1-TaqIA and DRD4 VNTR polymorphisms were obtained. All subjects underwent neuropsychological assessment. Eating behavior traits were evaluated. The ‘DRD2/ANKK1-TaqIA A1-allele status’ had a significant effect on almost all the executive variables, but no significant ‘DRD4 7R-allele status’ effects were observed for any of the executive variables analyzed. There was a significant ‘group’ x ‘DRD2/ANKK1-TaqIA A1-allele status’ interaction effect on LN and ‘group’ x ‘DRD4 7R-allele status’ interaction effect on TMT B-A score. Being obese and a carrier of the A1 allele of DRD2/ANKK1-TaqIA or the 7R allele of DRD4 VNTR polymorphisms could confer a weakness as regards the performance of executive functions.

Influence of extraneurological insults on ventricular enlargement and neuropsychological functioning after moderate and severe traumatic brain injury

Extraneurological insults secondary to TBI such as hypotension or hypoxia have been associated with mortality and morbidity. The purpose of this study was to investigate the influence of systemic complications on both neuropsychological outcome and cerebral atrophy. Fifty-seven patients selected from 122 consecutive admissions were studied. Data on the type and severity of injury as well as other systemic insults were collected prior to and during the first 3 days of hospitalization. These data included the presence or absence of a hypoxic episode during the pre-hospital period, the presence and degree of hypoxia, hypercapnia, anemia, hypotension and intracranial hypertension, pupillary reactivity, Glasgow Coma Scale score and coma duration. From the last control CT scan image, performed 6 months post-injury, four different indexes of ventricular dilatation were calculated. Neuropsychological assessment at 6 months included tests of verbal and visual memory, visuoconstructive functions, fine motor speed, and frontal lobe functions. Our results showed that hypoxia and hypotension were related to neuropsychological outcome and long-term ventricular enlargement. Hypoxic episodes prior to hospitalization were related to third ventricle dilatation and to adverse neurological and cognitive outcomes, especially to attention, motor speed, mental flexibility, fluency and verbal memory impairments, suggesting fronto-striatal and hippocampal dysfunction. We conclude that the effect of extraneurological insults on brain structure and function may be as important as the severity of the primary injury.

Functional connectivity in obesity during reward processing

Obesity is a health problem that has become a major focus of attention in recent years. There is growing evidence of an association between obesity and differences in reward processing. However, it is not known at present whether these differences are linked exclusively to food, or whether they can be detected in other rewarding stimuli. We compared responses to food, rewarding non-food and neutral pictures in 18 young adults with obesity and 19 normal-weight subjects using independent component analysis. Both groups modulated task-related activity in a plausible way. However, in response to both food and non-food rewarding stimuli, participants with obesity showed weaker connectivity in a network involving activation of frontal and occipital areas and deactivation of the posterior part of the default mode network. In addition, obesity was related with weaker activation of the default mode network and deactivation of frontal and occipital areas while viewing neutral stimuli. Together, our findings suggest that obesity is related to a different allocation of cognitive resources in a fronto-occipital network and in the default mode network.

Neuropsychological Outcome in Relation to the Traumatic Coma Data Bank Classification of Computed Tomography Imaging

The Traumatic Coma Data Bank (TCDB) classification of CT (computed tomography) scan has been related to the general outcome and intracranial pressure evolution. Our aim was to analyse the relationship of this classification with neuropsychological outcome and late indices of ventricular dilatation. Fifty-seven patients with a moderate or severe head injury (mean admission Glasgow Coma Scale Score, 7.7) were studied from 122 consecutive cases. There were 49 males and 8 females (mean age, 27.7 years). Subjects were classified into TCDB categories on the basis of their most serious acute CT scan finding. From the last control CT scan image, performed at a mean of 6.12 months postinjury, several measures of ventricular dilatation were calculated. Neuropsychological assessment at 6-month included tests of verbal and visual memory, visuoconstructive functions, fine motor speed, and frontal lobe functions. Patients with diffuse injury type I showed better neuropsychological outcome than patients with more severe diffuse injuries and those with mass lesions. Within the diffuse injury groups, the degree of diffuse damage was related to measures of verbal memory and attention and cognitive flexibility. Ventricular enlargement was more evident in patients with mass lesions and it decreased in the remaining groups as the severity of diffuse injury diminished. These results show that there is a relationship between acute intracranial lesion diagnosis according to TCDB classification and neuropsychological results and ventricular dilatation indices at 6 months postinjury.

Differences in visual vs. verbal memory impairments as a result of focal temporal lobe damage in patients with traumatic brain injury

Primary objective: The aim of the present study was to determine whether the type of lesion in a sample of moderate and severe traumatic brain injury (TBI) was related to material-specific memory impairment. Methods and procedures: Fifty-nine patients with TBI were classified into three groups according to whether the site of the lesion was right temporal, left temporal or diffuse. Six-months post-injury, visual (Warringtons Facial Recognition Memory Test and Reys Complex Figure Test) and verbal (Reys Auditory Verbal Learning Test) memories were assessed. Main outcome and results: Visual memory deficits assessed by facial memory were associated with right temporal lobe lesion, whereas verbal memory performance assessed with a list of words was related to left temporal lobe lesion. The group with diffuse injury showed both verbal and visual memory impairment. Conclusions: These results suggest a material-specific memory impairment in moderate and severe TBI after focal temporal lesions and a non-specific memory impairment after diffuse damage.