Neuroinflammation: A Modifiable Pathway Linking Obesity, Alzheimer's disease, and Depression.

Obesity, depression and Alzheimer's disease (AD) are three major interrelated modern health conditions with complex relationships. Early-life depression may serve as a risk factor for AD, while late-life depression may be a prodrome of AD. Depression affects approximately 23% of obese individuals, and depression itself raises the risk of obesity by 37%. Mid-life obesity independently increases AD risk, while late-life obesity, particularly metabolically healthy obesity, may offer protection against AD pathology. Chronic inflammation serves as a key mechanism linking obesity, AD, and depression, encompassing systemic inflammation from metabolic disturbances, immune dysregulation through the gut microbiome, and direct interactions with amyloid pathology and neuroinflammation. In this review, we explore the biological mechanisms of neuroinflammation in relation to obesity, AD, and depression. We assess the efficacy of therapeutic interventions targeting neuroinflammation and discuss current and future radiological imaging initiatives for studying neuroinflammation. By comprehending the intricate interplay among depression, obesity, and AD, especially the role of neuroinflammation, we can advance our understanding and develop innovative strategies for prevention and treatment.

Obesity, gut microbiota, and multiple sclerosis: Unraveling the connection.

Obesity is associated with chronic mild-grade systemic inflammation and neuroinflammation. Obesity in early childhood and adolescence is also a significant risk factor for multiple sclerosis (MS) development. However, the underlying mechanisms that explain the link between obesity and MS development are not fully explored. An increasing number of studies call attention to the importance of gut microbiota as a leading environmental risk factor mediating inflammatory central nervous system demyelination, particularly in MS. Obesity and high-calorie diet are also associated with disturbances in gut microbiota. Therefore, gut microbiota alteration is a plausible connection between obesity and the increased risk of MS development. A greater understanding of this connection could provide additional therapeutic opportunities, like dietary interventions, microbiota-derived products, and exogenous antibiotics and probiotics. This review summarizes the current evidence regarding the relationships between MS, obesity, and gut microbiota. We discuss gut microbiota as a potential link between obesity and increased risk for MS. Additional experimental studies and controlled clinical trials targeting gut microbiota are warranted to unravel the possible causal relationship between obesity and increased risk of MS.

Childhood obesity is linked to putative neuroinflammation in brain white matter, hypothalamus, and striatum.

Neuroinflammation is both a consequence and driver of overfeeding and weight gain in rodent obesity models. Advances in magnetic resonance imaging (MRI) enable investigations of brain microstructure that suggests neuroinflammation in human obesity. To assess the convergent validity across MRI techniques and extend previous findings, we used diffusion basis spectrum imaging (DBSI) to characterize obesity-associated alterations in brain microstructure in 601 children (age 9-11 years) from the Adolescent Brain Cognitive DevelopmentSM Study. Compared with children with normal-weight, greater DBSI restricted fraction (RF), reflecting neuroinflammation-related cellularity, was seen in widespread white matter in children with overweight and obesity. Greater DBSI-RF in hypothalamus, caudate nucleus, putamen, and, in particular, nucleus accumbens, correlated with higher baseline body mass index and related anthropometrics. Comparable findings were seen in the striatum with a previously reported restriction spectrum imaging (RSI) model. Gain in waist circumference over 1 and 2 years related, at nominal significance, to greater baseline RSI-assessed restricted diffusion in nucleus accumbens and caudate nucleus, and DBSI-RF in hypothalamus, respectively. Here we demonstrate that childhood obesity is associated with microstructural alterations in white matter, hypothalamus, and striatum. Our results also support the reproducibility, across MRI methods, of findings of obesity-related putative neuroinflammation in children.

Longitudinal Changes in Vision and Retinal Morphology in Wolfram Syndrome.

PURPOSE: To report long-term ophthalmic findings in Wolfram syndrome, including rates of visual decline, macular thinning, retinal nerve fiber layer (RNFL) thinning, and outer plexiform layer (OPL) lamination. DESIGN: Single-center, cohort study. METHODS: A total of 38 participants were studied, who underwent a complete ophthalmic examination as well as optical coherence tomography imaging of the macula and nerve on an annual basis. Linear mixed-effects models for longitudinal data were used to examine both fixed and random effects related to visual acuity and optic nerve quadrants of RNFL and macula thickness. RESULTS: Participants completed a mean of 6.44 years of follow-up (range 2-10 years). Visual acuity declined over time in all participants, with a mean slope of 0.059 logMAR/y (95% CI = 0.07-0.05 logMAR/y), although nearly 25% of participants experienced more rapid visual decline. RNFL thickness decreased in superior, inferior, and nasal quadrants (ß = -0.5 µm/y, -0.98 µm/y, -0.28 µm/y, respectively). OPL lamination was noted in 3 study participants, 2 of whom had autosomal dominant mutations. CONCLUSIONS: Our study describes the longest and largest natural history study of visual acuity decline and retinal morphometry in Wolfram syndrome to date. Results suggest that there are slower and faster progressing subgroups and that OPL lamination is present in some individuals with this disease.

External Ear Diseases: A Comprehensive Review of the Pathologies With Neuroradiological Considerations.

The peripheral auditory system is subdivided into 3 compartments: the external, middle, and inner ear. Historically, the middle and inner ear have garnered more attention in the imaging literature, due to their intricate anatomy and complexity of pathologies. The external ear, however, has attained less recognition given its relatively straightforward anatomy and convenience of direct visual examination. The continued advancement in computed tomography and magnetic resonance imaging has expanded the role of radiology in the evaluation of the external ear lesions. The purpose of this article is to offer a comprehensive review of external ear pathologies, including congenital, inflammatory, infectious, traumatic, neoplastic, and rare disease entities and their imaging findings.

The Forgotten Phacomatoses: A Neuroimaging Review of Rare Neurocutaneous Disorders.

Phakomatoses, or neurocutaneous syndromes, are a heterogeneous group of rare genetic disorders that predominantly affect structures arising from the embryonic ectoderm, namely the skin, eye globe, retina, tooth enamel, and central nervous system. Other organs are also involved in some syndromes, mainly cardiovascular, pulmonary, renal, and musculoskeletal systems. Currently, more than sixty distinct entities belonging to this category have been described in the literature. Common phakomatoses include conditions like Neurofibromatosis and Tuberous sclerosis. Several review papers have focused on various aspects of these common conditions, including clinical presentation, genetic and molecular basis, and neuroimaging features. In this review, we focus on rare neurocutaneous syndromes: Melanophakomatoses (Ie, Neurocutaneous Melanosis, and Incontinentia Pigmenti), Vascular Phakomatoses (Ie, Ataxia Telangiectasia and PHACE Syndrome), and other conditions such as Cowden Syndrome, Basal Nevus Syndrome, Schwannomatosis, Progressive Facial Hemiatrophy, Gomez-Lopez-Hernandez Syndrome, Wyburn-Mason Syndrome, CHILD Syndrome, and Proteus Syndrome. We also review the neuroradiologic manifestations of these conditions as a guide for neurologists and neuroradiologists in their daily practice.

Coronary Artery Calcification and Plaque Characteristics in People Living With HIV: A Systematic Review and Meta-Analysis.

Background Studies have reported that people living with HIV have higher burden of subclinical cardiovascular disease, but the data are not adequately synthesized. We performed meta-analyses of studies of coronary artery calcium and coronary plaque in people living with HIV. Methods and Results We performed systematic search in electronic databases, and data were abstracted in standardized forms. Study-specific estimates were pooled using meta-analysis. 43 reports representing 27 unique studies and involving 10 867 participants (6699 HIV positive, 4168 HIV negative, mean age 52 years, 86% men, 32% Black) were included. The HIV-positive participants were younger (mean age 49 versus 57 years) and had lower Framingham Risk Score (mean score 6 versus 18) compared with the HIV-negative participants. The pooled estimate of percentage with coronary artery calcium >0 was 45% (95% CI, 43%-47%) for HIV-positive participants, and 52% (50%-53%) for HIV-negative participants. This difference was no longer significant after adjusting for difference in Framingham Risk Score between the 2 groups. The odds ratio of coronary artery calcium progression for HIV-positive versus -negative participants was 1.64 (95% CI, 0.91-2.37). The pooled estimate for prevalence of noncalcified plaque was 49% (95% CI, 47%-52%) versus 20% (95% CI, 17%-23%) for HIV-positive versus HIV-negative participants, respectively. Odds ratio for noncalcified plaque for HIV-positive versus -negative participants was 1.23 (95% CI, 1.08-1.38). There was significant heterogeneity that was only partially explained by available study-level characteristics. Conclusions People living with HIV have higher prevalence of noncalcified coronary plaques and similar prevalence of coronary artery calcium, compared with HIV-negative individuals. Future studies on coronary artery calcium and plaque progression can further elucidate subclinical atherosclerosis in people living with HIV.

Methodological Rigor and Temporal Trends of Cardiovascular Medicine Meta-Analyses in Highest-Impact Journals.

Background Well-conducted meta-analyses are considered to be at the top of the evidence-based hierarchy pyramid, with an expansion of these publications within the cardiovascular research arena. There are limited data evaluating the trends and quality of such publications. The objective of this study was to evaluate the methodological rigor and temporal trends of cardiovascular medicine-related meta-analyses published in the highest impact journals. Methods and Results Using the Medline database, we retrieved cardiovascular medicine-related systematic reviews and meta-analyses published in The New England Journal of Medicine, The Lancet, Journal of the American Medical Association, The British Medical Journal, Annals of Internal Medicine, Circulation, European Heart Journal, and Journal of American College of Cardiology between January 1, 2012 and December 31, 2018. Among 6406 original investigations published during the study period, meta-analyses represented 422 (6.6%) articles, with an annual decline in the proportion of published meta-analyses (8.7% in 2012 versus 4.6% in 2018, Ptrend=0.002). A substantial number of studies failed to incorporate elements of Preferred Reporting Items for Systematic Reviews and Meta-Analyses or Meta-Analysis of Observational Studies in Epidemiology guidelines (51.9%) and only a minority of studies (10.4%) were registered in PROSPERO (International Prospective Register of Systematic Reviews). Fewer manuscripts failed to incorporate the Preferred Reporting Items for Systematic Reviews and Meta-Analyses or Meta-Analysis of Observational Studies in Epidemiology elements over time (60.2% in 2012 versus 40.0% in 2018, Ptrend<0.001) whereas the number of meta-analyses registered at PROSPERO has increased (2.4% in 2013 versus 17.5% in 2018, Ptrend<0.001). Conclusions The proportion of cardiovascular medicine-related meta-analyses published in the highest impact journals has declined over time. Although there is an increasing trend in compliance with quality-based guidelines, the overall compliance remains low.

Nucleus accumbens microstructure mediates the relationship between obesity and eating behavior in adults.

OBJECTIVE: Basal ganglia regions are part of the brain's reward-processing networks and are implicated in the neurobiology of obesity and eating disorders. This study examines basal ganglia microstructural properties in adults with and without obesity. METHODS: Diffusion basis spectrum imaging (DBSI) images were analyzed to obtain putative imaging markers of neuroinflammation. Relationships between basal ganglia DBSI metrics and reward sensitivity and eating behaviors were also explored. RESULTS: A total of 46 participants (25 people with obesity; aged 20-40 years; 37 women) were included. Relative to the people in the normal-weight group, people with obesity had smaller caudate and larger nucleus accumbens (NAcc) volumes (p < 0.05) and lower DBSI fiber fraction (reflecting apparent axonal/dendrite density) in NAcc and putamen, higher DBSI nonrestricted fraction (reflecting tissue edema) in NAcc and caudate, and higher DBSI restricted fraction (reflecting tissue cellularity) in putamen (p ≤ 0.01, all). Increased emotional and reward eating behaviors were related to lower NAcc axonal/dendrite density and greater tissue edema (p ≤ 0.002). The relationships between emotional eating and adiposity measures were mediated by NAcc microstructure. CONCLUSIONS: These findings provide evidence that microstructural alterations in basal ganglia relate to obesity and insights linking NAcc microstructure and eating behavior in adults.

Obesity and White Matter Neuroinflammation Related Edema in Alzheimer's Disease Dementia Biomarker Negative Cognitively Normal Individuals.

BACKGROUND: Obesity is related to quantitative neuroimaging abnormalities including reduced gray matter volumes and impaired white matter microstructural integrity, although the underlying mechanisms are not well understood. OBJECTIVE: We assessed influence of obesity on neuroinflammation imaging that may mediate brain morphometric changes. Establishing the role of neuroinflammation in obesity will enhance understanding of this modifiable disorder as a risk factor for Alzheimer's disease (AD) dementia. METHODS: We analyzed brain MRIs from 104 cognitively normal participants (CDR = 0) and biomarker negativity for CSF amyloid or tau. We classified body mass index (BMI) as normal (BMI <25, N = 62) or overweight and obese (BMI ≥25, N = 42). Blood pressure was measured. BMI and blood pressure classifications were related to neuroinflammation imaging (NII) derived edema fraction in 17 white matter tracts. This metric was also correlated to hippocampal volumes and CSF biomarkers of inflammation and neurodegeneration: YKL-40, SNAP25, VILIP, tau, and NFL. RESULTS: Participants with BMI <25 had lower NII-derived edema fraction, with protective effects of normal blood pressure. Statistically significant white matter tracts included the internal capsule, external capsule, and corona radiata, FDR correc-ted for multiple comparisons to alpha = 0.05. Higher NII-derived edema fractions in the internal capsule, corpus callosum, gyrus, and superior fronto-occipital fasciculus were related with smaller hippocampal volumes only in individuals with BMI ≥25. There were no statistically significant correlations between NII-derived edema fraction and CSF biomarkers. CONCLUSION: We demonstrate statistically significant relationships between neuroinflammation, elevated BMI, and hippocampal volume, raising implications for neuroinflammation mechanisms of obesity-related brain dysfunction in cognitively normal elderly.

Ocular and brain imaging findings in Peters' anomaly: A case report and literature review.

Peters' anomaly is a rare congenital eye condition characterized by anterior segment dysgenesis and commonly presents as unilateral or bilateral corneal opacity in the early neonatal period. Peters' anomaly is often associated with congenital brain and skull abnormalities, which are frequently overlooked. In this paper, we present a case of a 5-day-old female neonate with Peters' anomaly, and review the literature for similar reports that describe associated brain imaging findings. In our case, imaging studies show abnormalities involving the anterior segments of both globes with absent intracranial manifestations. Although Peters' anomaly is a condition of interest for ophthalmologists, radiological studies should be performed, and neuroradiologists should be aware of the imaging findings associated with this rare entity.

Striatal Dopamine Responses to Feeding are Altered in People with Obesity.

OBJECTIVE: This study determined whether striatal dopamine (DA) release is affected by food ingestion and whether the DA response to high-calorie food images is greater in the fasted than in the fed state in people with obesity. METHODS: Striatal DA release was evaluated in 10 people with obesity and prediabetes after consuming a meal to satiation and after fasting overnight as well as in response to viewing images of high-calorie compared with low-calorie foods after consuming a meal to satiation or fasting overnight by using positron emission tomography with [11 C]raclopride injection. RESULTS: Striatal DA D2/D3 receptor availability was not different during fasted and fed conditions. Viewing images of high-calorie foods induced striatal DA release relative to viewing images of low-calorie foods (P < 0.05), but there was no difference in the magnitude of the response between fasting and fed conditions. CONCLUSIONS: People with obesity and prediabetes do not increase striatal DA release after eating a meal to satiation compared with fasting overnight and fail to inhibit DA release in response to high-calorie food stimuli after eating a meal to satiation. These data suggest that impaired DA signaling contributes to greater energy intake during meals in this population.

Thalamic aphasia secondary to glioblastoma multiforme.

BACKGROUND: Thalamic aphasia is an unusual clinical presentation of brain neoplasm with few cases reported. Herein, we present a case of an adult woman with thalamic aphasia due to glioblastoma of the thalamus. CASE PRESENTATION: A 57-year-old female patient presented with difficulty walking, slow speech and cognition and altered mental status. At baseline, she was conversant and interactive. Physical examination showed right hemiparesis in addition to word finding difficulties, an impaired naming of objects and semantic paraphasia but preserved repetition and comprehension. The remaining neurological exam was otherwise unremarkable. Brain CT and brain MRI scans showed a left thalamic lesion that is centrally necrotic and peripherally enhancing suggestive of a high-grade neoplasm. Eventually, histopathological examination of brain biopsy confirmed the diagnosis of glioblastoma multiforme. Thalamic aphasia was proposed as an explanation for the neurological symptoms observed in this patient. CONCLUSIONS: This patient demonstrates an unusual presentation of glioblastoma multiforme as thalamic aphasia. It may also point to the potential contribution of the understanding of how thalamic aphasia evolves to characterize the role of the thalamus in language functions.

Efficacy and safety of gamma knife radiosurgery for posterior cranial fossa meningioma: a systematic review.

The management of posterior cranial fossa meningioma [PCFM] is challenging and many neurosurgeons advise gamma knife radiosurgery [GKRS] as a modality for its upfront or adjuvant treatment. Due to the varying radiosurgical response based on lesion location, tumor biology, and radiation dosage, we performed a pioneer attempt in doing a systematic review analyzing the treatment efficacy and safety profile of GKRS for PCFM based on current literature. A systematic review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses [PRISMA] guidelines. A thorough literature search was conducted on PubMed, Web of science, and Cochrane data base; articles were selected systematically based on PRISMA protocol, reviewed completely, and relevant data was summarized and discussed. A total of 18 publications pertaining to GKRS for PCFM were included with a pooled sample size of 2131 patients. The median pre-GKRS tumor volume ranged from 2.28 to 10.5 cm [3]. Primary GKRS was administered in 61.1% of the pooled study cohorts, adjuvant treatment in 32.9%, and salvage therapy in 6.5% patients. Majority of the meningiomas were WHO grade 1 tumors (99.7%). The pooled mean marginal dose in the studies was 13.6 Gy (range 12-15.2 Gy) while the mean of maximum doses was 28.6 Gy (range 25-35 Gy). Most studies report an excellent radiosurgical outcome including the tumor control rate and the progression-free survival [PFS] of over 90%. The tumor control, PFS, and adverse radiation effect [ARE] rates in author's series were 92.3%, 91%, and 9.6%, respectively. The favorable radiosurgical outcome depends on multiple factors such as small tumor volume, absence of previous radiotherapy, tumor location, elderly patients, female gender, longer time from symptom onset, and decreasing maximal dose. GKRS as primary or adjuvant treatment modality needs to be considered as a promising management strategy for PCFM in selected patients in view of the growing evidence of high tumor control rate, improved neurological functions, and low incidence of ARE. The use of multiple isocenters, 3-D image planning, and limit GKRS treatment to tumors less than 3.5 cm help to avoid complications and achieve the best results. The treatment decisions in PCFM cases must be tailored and should consider the factors such as radiological profile, symptom severity, performance level, and patient preference for a good outcome.

Developmental hypomyelination in Wolfram syndrome: new insights from neuroimaging and gene expression analyses.

Wolfram syndrome is a rare multisystem disorder caused by mutations in WFS1 or CISD2 genes leading to brain structural abnormalities and neurological symptoms. These abnormalities appear in early stages of the disease. The pathogenesis of Wolfram syndrome involves abnormalities in the endoplasmic reticulum (ER) and mitochondrial dynamics, which are common features in several other neurodegenerative disorders. Mutations in WFS1 are responsible for the majority of Wolfram syndrome cases. WFS1 encodes for an endoplasmic reticulum (ER) protein, wolframin. It is proposed that wolframin deficiency triggers the unfolded protein response (UPR) pathway resulting in an increased ER stress-mediated neuronal loss. Recent neuroimaging studies showed marked alteration in early brain development, primarily characterized by abnormal white matter myelination. Interestingly, ER stress and the UPR pathway are implicated in the pathogenesis of some inherited myelin disorders like Pelizaeus-Merzbacher disease, and Vanishing White Matter disease. In addition, exploratory gene-expression network-based analyses suggest that WFS1 expression occurs preferentially in oligodendrocytes during early brain development. Therefore, we propose that Wolfram syndrome could belong to a category of neurodevelopmental disorders characterized by ER stress-mediated myelination impairment. Further studies of myelination and oligodendrocyte function in Wolfram syndrome could provide new insights into the underlying mechanisms of the Wolfram syndrome-associated brain changes and identify potential connections between neurodevelopmental disorders and neurodegeneration.

Calvarial Langerhans cell histiocytosis in an Adult: Typical imaging findings in an atypical age group.

Langerhans Cell Histiocytosis (LCH) is a rare disorder characterized by neoplastic proliferation of Langerhans-type dendritic cells. LCH is most frequently encountered in the pediatric populations, and involvement of the skeletal system is a common manifestation. Herein, we report a case of LCH presented as an isolated skull lesion in a 66-year-old patient. This presentation has never been reported in the literature at this advanced age and suggests that, despite being exceptionally rare, clinicians should consider LCH in the differential diagnosis of skull lesions in the elderly with classical radiological appearance.

Posterior reversible encephalopathy syndrome with isolated infratentorial involvement: A case report.

Posterior reversible encephalopathy syndrome (PRES) is a clinical and radiological entity of acute neurological symptoms associated with characteristic MRI finding. Vasogenic edema in the white matter of parieto-occipital regions is the classical MRI findings. Spinal cord involvement in PRES is extremely rare and frequently underrecognized condition. Recently, a variant-type PRES with isolated involvement of infratentorial structures is getting more attention. Herein, we present a case of hypertensive emergency and associated radiological features of PRES with isolated involvement of the brain stem, cerebellum, and spinal cord.