Cerebral Involvement in Stargardt's Disease: A VBM and TBSS Study.

PURPOSE. To assess whether and to what extent macro- and/or microstructural modifications are present in the brain of patients with selective central visual loss due to a juvenile macular degeneration, Stargardt's disease (STGD), taking advantage of the complementary information provided by voxel-based morphometry (VBM) and diffusion tensor imaging (DTI). METHODS. Eighteen patients with clinical and molecular diagnosis of STGD related to ABCA4 mutations and 23 normally sighted volunteers of comparable age and sex were enrolled. Structural T1-weighted (T1w) volumes, for brain tissue volume assessment by segmentation, and DTI, for the investigation of diffusivity parameters via a tract-based spatial statistics (TBSS) procedure, were acquired at 3 Tesla in all subjects. All patients underwent a complete ophthalmologic examination, including best-corrected visual acuity (BCVA), biomicroscopy, ophthalmoscopy, electroretinography (ERG), microperimetry, and optical coherence tomography (OCT). Correlations between imaging data and clinical measures were tested. RESULTS. Stargardt's disease patients showed a significant gray matter (GM) loss bilaterally in the occipital cortices, extending into the right precuneus, and in the fronto-orbital cortices. At TBSS, significant reductions in fractional anisotropy were detected throughout large regions in the supratentorial white matter (WM), more pronounced in the posterior areas. Gray matter volume correlated directly with mean visual sensitivity in the right middle frontal and left calcarine gyri, and inversely with retinal thickness in the left supramarginal gyrus. CONCLUSIONS. In STGD, widespread microstructural WM alterations are present, suggestive of minor fiber loss coupled with GM loss, also in cortical regions not traditionally linked to visual pathways, at least partly related to the retinal damage. Purpose: To assess whether and to what extent macro- and/or microstructural modifications are present in the brain of patients with selective central visual loss due to a juvenile macular degeneration, Stargardt's disease (STGD), taking advantage of the complementary information provided by voxel-based morphometry (VBM) and diffusion tensor imaging (DTI). Methods: Eighteen patients with clinical and molecular diagnosis of STGD related to ABCA4 mutations and 23 normally sighted volunteers of comparable age and sex were enrolled. Structural T1-weighted (T1w) volumes, for brain tissue volume assessment by segmentation, and DTI, for the investigation of diffusivity parameters via a tract-based spatial statistics (TBSS) procedure, were acquired at 3 Tesla in all subjects. All patients underwent a complete ophthalmologic examination, including best-corrected visual acuity (BCVA), biomicroscopy, ophthalmoscopy, electroretinography (ERG), microperimetry, and optical coherence tomography (OCT). Correlations between imaging data and clinical measures were tested. Results: Stargardt's disease patients showed a significant gray matter (GM) loss bilaterally in the occipital cortices, extending into the right precuneus, and in the fronto-orbital cortices. At TBSS, significant reductions in fractional anisotropy were detected throughout large regions in the supratentorial white matter (WM), more pronounced in the posterior areas. Gray matter volume correlated directly with mean visual sensitivity in the right middle frontal and left calcarine gyri, and inversely with retinal thickness in the left supramarginal gyrus. Conclusions: In STGD, widespread microstructural WM alterations are present, suggestive of minor fiber loss coupled with GM loss, also in cortical regions not traditionally linked to visual pathways, at least partly related to the retinal damage

Limbic-thalamo-cortical projections and reward-related circuitry integrity affects eating behavior: A longitudinal DTI study in adolescents with restrictive eating disorders.

Few studies have used diffusion tensor imaging (DTI) to investigate the micro-structural alterations of WM in patients with restrictive eating disorders (rED), and longitudinal data are lacking. Twelve patients with rED were scanned at diagnosis and after one year of family-based treatment, and compared to twenty-four healthy controls (HCs) through DTI analysis. A tract-based spatial statistics procedure was used to investigate diffusivity parameters: fractional anisotropy (FA) and mean, radial and axial diffusivities (MD, RD and AD, respectively). Reduced FA and increased RD were found in patients at baseline in the corpus callosum, corona radiata and posterior thalamic radiation compared with controls. However, no differences were found between follow-up patients and controls, suggesting a partial normalization of the diffusivity parameters. In patients, trends for a negative correlation were found between the baseline FA of the right anterior corona radiata and the Eating Disorder Examination Questionnaire total score, while a positive trend was found between the baseline FA in the splenium of corpus callosum and the weight loss occurred between maximal documented weight and time of admission. A positive trend for correlation was also found between baseline FA in the right anterior corona radiata and the decrease in the Obsessive-Compulsive Inventory Revised total score over time. Our results suggest that the integrity of the limbic-thalamo-cortical projections and the reward-related circuitry are important for cognitive control processes and reward responsiveness in regulating eating behavior

Brain Structure and Function in Adolescents with Atypical Anorexia Nervosa

Atypical anorexia nervosa (AAN) has a high incidence in adolescents, resulting in significant morbidity and mortality. The weight loss is generally less pronounced than that experienced in full-syndrome anorexia nervosa (AN), but the medical consequences can be as severe. Neuroimaging could improve our knowledge regarding the pathogenesis of eating disorders, however research on adolescents is limited, and no neuroimaging studies have been conducted in AAN. In paper I, we investigated brain structure through a voxel-based morphometry analysis in 22 drug-naïve adolescent females newly-diagnosed with AAN, and 38 age- and sex-matched healthy controls. In Paper II, we investigated white matter microstructural integrity on 25 drug-naïve adolescent patients with AAN and 25 healthy controls, using diffusion tensor imaging with a tract-based spatial statistics approach. No differences in brain structure could be detected, indicating preserved regional grey matter volumes and white matter diffusivity in patients with AAN compared to controls. These findings suggest that previous observations of brain structure alterations in full syndrome AN may constitute state-related consequences of severe underweight. Alternatively, the preservation of brain structure might indeed differentiate AAN from AN. In paper III, we investigated resting-state functional connectivity in 22 drug-naïve adolescent patients with AAN, and 24 healthy controls. We report reduced connectivity in patients in brain areas involved in face-processing and social cognition, while an increased connectivity, correlating with depressive symptoms, was found in areas involved in the multimodal integration of sensory stimuli, aesthetic judgment, and social rejection anxiety. These findings point toward a core role for an altered development of socio-emotional skills in the pathogenesis of AAN. In Paper IV, we investigated neural connectivity underlying visual processing of foods with different caloric content in a sample of 28 adolescent females diagnosed with AAN, and 33 age- and sex-matched healthy controls. Our results showed higher connectivity in patients in pathways related to the integration of sensory input and memory retrieval, in response to food with high caloric content. This, however, was coupled to lower connectivity in salience and attentional networks, and lower connectivity between areas involved in visual food cues processing and appetite regulatory regions. Thus, despite food with high caloric content is associated to greater processing of somatosensory information in patients, it is attributed less salience and engages patients’ attention less than food with low caloric content

Brain Structure and Function in Adolescents with Atypical Anorexia Nervosa

Atypical anorexia nervosa (AAN) has a high incidence in adolescents, resulting in significant morbidity and mortality. The weight loss is generally less pronounced than that experienced in full-syndrome anorexia nervosa (AN), but the medical consequences can be as severe. Neuroimaging could improve our knowledge regarding the pathogenesis of eating disorders, however research on adolescents is limited, and no neuroimaging studies have been conducted in AAN. In paper I, we investigated brain structure through a voxel-based morphometry analysis in 22 drug-naïve adolescent females newly-diagnosed with AAN, and 38 age- and sex-matched healthy controls. In Paper II, we investigated white matter microstructural integrity on 25 drug-naïve adolescent patients with AAN and 25 healthy controls, using diffusion tensor imaging with a tract-based spatial statistics approach. No differences in brain structure could be detected, indicating preserved regional grey matter volumes and white matter diffusivity in patients with AAN compared to controls. These findings suggest that previous observations of brain structure alterations in full syndrome AN may constitute state-related consequences of severe underweight. Alternatively, the preservation of brain structure might indeed differentiate AAN from AN. In paper III, we investigated resting-state functional connectivity in 22 drug-naïve adolescent patients with AAN, and 24 healthy controls. We report reduced connectivity in patients in brain areas involved in face-processing and social cognition, while an increased connectivity, correlating with depressive symptoms, was found in areas involved in the multimodal integration of sensory stimuli, aesthetic judgment, and social rejection anxiety. These findings point toward a core role for an altered development of socio-emotional skills in the pathogenesis of AAN. In Paper IV, we investigated neural connectivity underlying visual processing of foods with different caloric content in a sample of 28 adolescent females diagnosed with AAN, and 33 age- and sex-matched healthy controls. Our results showed higher connectivity in patients in pathways related to the integration of sensory input and memory retrieval, in response to food with high caloric content. This, however, was coupled to lower connectivity in salience and attentional networks, and lower connectivity between areas involved in visual food cues processing and appetite regulatory regions. Thus, despite food with high caloric content is associated to greater processing of somatosensory information in patients, it is attributed less salience and engages patients’ attention less than food with low caloric content

Brain and Cognitive Development in Adolescents with Anorexia Nervosa : A Systematic Review of fMRI Studies

Anorexia nervosa (AN) is an eating disorder often occurring in adolescence. AN has one of the highest mortality rates amongst psychiatric illnesses and is associated with medical complications and high risk for psychiatric comorbidities, persisting after treatment. Remission rates range from 23% to 33%. Moreover, weight recovery does not necessarily reflect cognitive recovery. This issue is of particular interest in adolescence, characterized by progressive changes in brain structure and functional circuitries, and fast cognitive development. We reviewed existing literature on fMRI studies in adolescents diagnosed with AN, following PRISMA guidelines. Eligible studies had to: (1) be written in English; (2) include only adolescent participants; and (3) use block-design fMRI. We propose a pathogenic model based on normal and AN-related neural and cognitive maturation during adolescence. We propose that underweight and delayed puberty-caused by genetic, environmental, and neurobehavioral factors-can affect brain and cognitive development and lead to impaired cognitive flexibility, which in turn sustains the perpetuation of aberrant behaviors in a vicious cycle. Moreover, greater punishment sensitivity causes a shift toward punishment-based learning, leading to greater anxiety and ultimately to excessive reappraisal over emotions. Treatments combining physiological and neurobehavioral rationales must be adopted to improve outcomes and prevent relapses

Low neuroticism and cognitive performance are differently associated to overweight and obesity : A cross-sectional and longitudinal UK Biobank study.

BACKGROUND: A growing body of research has linked personality traits to cognitive performance. This relationship might play a role in the predisposition toward obesity. Neuroticism and executive function seem to be particularly involved, and reduced executive function has been proposed to underlie the association of neuroticism with sedentary behaviors and fatty food consumption. Despite the link between neuroticism, cognitive functions and obesity has been largely reported, conflicting evidence exists. Moreover, information regarding other cognitive domains, and studies on overweight individuals, are still scarce. METHODS: We examined cross-sectional associations of neuroticism and cognitive function with overweight and obesity in a sample of 170 310 individuals from the UK Biobank cohort, adjusted for sociodemographic and life-style factors. Measures on fluid intelligence (FI) (reasoning ability), trail making test (TMT) (executive function), numeric memory test and pairs matching (PM) task (short-term memory) were extracted from the database. Correlations between neuroticism and cognitive performance were explored. Moreover, we investigated whether neuroticism and executive function could predict BMI variability over time. RESULTS: Reduced FI and short-term memory were associated with overweight and obesity, while reduced executive function was associated with obesity but not with overweight. Low neuroticism was associated with being overweight rather than lean or obese independently of gender and life-style. Furthermore, baseline neuroticism scores could predict BMI variations over 5-10 years follow-up, and high neuroticism correlated with lower cognitive performance. CONCLUSIONS: Lower cognitive performance is associated with both overweight and obesity, except for executive function, which was only related to obesity. Neuroticism correlated with performance on most of the cognitive domains tested, supporting the link between personality and cognition. Our findings also support the role of neuroticism in leading to greater weight variability over time, rather than to overweight/obesity itself

Altered cerebellar-insular-parietal-cingular subnetwork in adolescents in the earliest stages of anorexia nervosa : a network-based statistic analysis

To date, few functional magnetic resonance imaging (fMRI) studies have explored resting-state functional connectivity (RSFC) in long-lasting anorexia nervosa (AN) patients via graph analysis. The aim of the present study is to investigate, via a graph approach (i.e., the network-based statistic), RSFC in a sample of adolescents at the earliest stages of AN (i.e., AN duration less than 6 months). Resting-state fMRI data was obtained from 15 treatment-naive female adolescents with AN restrictive type (AN-r) in its earliest stages and 15 age-matched healthy female controls. A network-based statistic analysis was used to isolate networks of interconnected nodes that differ between the two groups. Group comparison showed a decreased connectivity in a sub-network of connections encompassing the left and right rostral ACC, left paracentral lobule, left cerebellum (10th sub-division), left posterior insula, left medial fronto-orbital gyrus, and right superior occipital gyrus in AN patients. Results were not associated to alterations in intranodal or global connectivity. No sub-networks with an increased connectivity were identified in AN patients. Our findings suggest that RSFC may be specifically affected at the earliest stages of AN. Considering that the altered sub-network comprises areas mainly involved in somatosensory and interoceptive information and processing and in emotional processes, it could sustain abnormal integration of somatosensory and homeostatic signals, which may explain body image disturbances in AN. Further studies with larger samples and longitudinal designs are needed to confirm our findings and better understand the role and consequences of such functional alterations in AN

Disruption of Accumbens and Thalamic White Matter Connectivity Revealed by Diffusion Tensor Tractography in Young Men with Genetic Risk for Obesity

Background: Neurovascular coupling is associated with white matter (WM) structural integrity, and it is regulated by specific subtypes of dopaminergic receptors. An altered activity of such receptors, highly expressed in reward-related regions, has been reported in carriers of obesity-risk alleles of the fat mass and obesity associated (FTO) gene. Among the reward-related regions, the thalamus and the nucleus accumbens are particularly vulnerable to blood pressure dysregulation due to their peculiar anatomo-vascular characteristics, and have been consistently reported to be altered in early-stage obesity. We have thus hypothesized that a disruption in thalamus and nucleus accumbens WM microstructure, possibly on neurovascular basis, could potentially be a predisposing factor underlying the enhanced risk for obesity in the risk-allele carriers. Methods: We have tested WM integrity in 21 male participants genotyped on the FTO risk single nucleotide polymorphisms (SNP) rs9939609, through a deterministic tractography analysis. Only homozygous participants (9 AA, 12 TT) were included. 11 tracts were selected and categorized as following according to our hypothesis: “risk tracts”, “obesity-associated tracts”, and a control tract (forcpes major). We investigated whether an association existed between genotype, body mass index (BMI) and WM microstructural integrity in the “risk-tracts” (anterior thalamic radiation and accumbofrontal fasciculus) compared to other tracts. Moreover, we explored whether WM diffusivity could be related to specific personality traits in terms of punishment and reward sensitivity, as measure by the BIS/BAS questionnaire. Results: An effect of the genotype and an interaction effect of genotype and BMI were detected on the fractional anisotropy (FA) of the “risk tracts”. Correlations between WM diffusivity parameters and measures of punishment and reward sensitivity were also detected in many WM tracts of both networks. Conclusions: A disruption of the structural connectivity from the nucleus accumbens and the thalamus might occur early in carriers of the FTO AA risk-allele, and possibly act as a predisposing factor to the development of obesity

The Cognitive Effects of Statins are Modified by Age

To reveal new insights into statin cognitive effects, we performed an observational study on a population-based sample of 245,731 control and 55,114 statin-taking individuals from the UK Biobank. Cognitive performance in terms of reaction time, working memory and fluid intelligence was analysed at baseline and two follow-ups (within 5-10 years). Subjects were classified depending on age (up to 65 and over 65 years) and treatment duration (1-4 years, 5-10 years and over 10 years). Data were adjusted for health- and cognition-related covariates. Subjects generally improved in test performance with repeated assessment and middle-aged persons performed better than older persons. The effect of statin use differed considerably between the two age groups, with a beneficial effect on reaction time in older persons and fluid intelligence in both age groups, and a negative effect on working memory in younger subjects. Our analysis suggests a modulatory impact of age on the cognitive side effects of statins, revealing a possible reason for profoundly inconsistent findings on statin-related cognitive effects in the literature. The study highlights the importance of characterising modifiers of statin effects to improve knowledge and shape guidelines for clinicians when prescribing statins and evaluating their side effects in patients