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New insights into the pathogenesis and prevention of tuberous sclerosis-associated neuropsychiatric disorders (TAND).

ABSTRACT: Tuberous sclerosis complex (TSC) is a multi-system disorder resulting from mutations in either the TSC1 or TSC2 genes leading to hyperactivation of mechanistic target of rapamycin (mTOR) signaling. TSC is commonly associated with autism (61%), intellectual disability (45%), and behavioral, psychiatric, intellectual, academic, neuropsychological, and psychosocial difficulties that are collectively referred to as TSC-associated neuropsychiatric disorders (TAND). More than 90% of children with TSC have epilepsy, including infantile spasms, and early onset of seizures, especially infantile spasms, is associated with greater impairment in intellectual development compared with individuals with TSC without seizures. Development of the mTOR inhibitors everolimus and sirolimus has led to considerable progress in the treatment of renal angiomyolipomata, pulmonary lymphangioleiomyomatosis, and subependymal giant cell astrocytomas in the brain. However, similar therapeutic progress is needed in the treatment of TAND.

SUBMITTER: Gipson TT

PROVIDER: S-EPMC5473405 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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New insights into the pathogenesis and prevention of tuberous sclerosis-associated neuropsychiatric disorders (TAND).

Gipson Tanjala T TT Johnston Michael V MV

F1000Research 20170609

Tuberous sclerosis complex (TSC) is a multi-system disorder resulting from mutations in either the <i>TSC1</i> or <i>TSC2</i> genes leading to hyperactivation of mechanistic target of rapamycin (mTOR) signaling. TSC is commonly associated with autism (61%), intellectual disability (45%), and behavioral, psychiatric, intellectual, academic, neuropsychological, and psychosocial difficulties that are collectively referred to as TSC-associated neuropsychiatric disorders (TAND). More than 90% of chil ...[more]

PMID: 28663780

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Project description:Background: Knowledge is increasing about TSC-Associated Neuropsychiatric Disorders (TAND), but little is known about the potentially confounding effects of intellectual ability (IA) on the rates of TAND across age, sex, and genotype. We evaluated TAND in (a) children vs. adults, (b) males vs. females, and (c) TSC1 vs. TSC2 mutations, after stratification for levels of IA, in a large, international cohort. Methods: Individuals of any age with a documented visit for TSC in the 12 months prior to enrolment were included. Frequency and percentages of baseline TAND manifestations were presented by categories of IA (no intellectual disability [ID, intelligence quotient (IQ)>70]; mild ID [IQ 50-70]; moderate-to-profound ID [IQ<50]). Chi-square tests were used to test associations between ID and TAND manifestations. The association between TAND and age (children vs. adults), sex (male vs. female), and genotype (TSC1 vs. TSC2) stratified by IA levels were examined using the Cochran-Mantel-Haenszel tests. Results: Eight hundred and ninety four of the 2,211 participants had formal IQ assessments. There was a significant association (P < 0.05) between levels of IA and the majority of TAND manifestations, except impulsivity (P = 0.12), overactivity (P = 0.26), mood swings (P = 0.08), hallucinations (P = 0.20), psychosis (P = 0.06), depressive disorder (P = 0.23), and anxiety disorder (P = 0.65). Once controlled for IA, children had higher rates of overactivity, but most behavioral difficulties were higher in adults. At the psychiatric level, attention deficit hyperactivity disorder (ADHD) was seen at higher rates in children while anxiety and depressive disorders were observed at higher rates in adults. Compared to females, males showed significantly higher rates of impulsivity and overactivity, as well as autism spectrum disorder (ASD) and ADHD. No significant age or sex differences were observed for academic difficulties or neuropsychological deficits. After controlling for IA no genotype-TAND associations were observed, except for higher rates of self-injury in individuals with TSC2 mutations. Conclusions: Findings suggest IA as risk marker for most TAND manifestations. We provide the first evidence of male preponderance of ASD and ADHD in individuals with TSC. The study also confirms the association between TSC2 and IA but, once controlling for IA, disproves the previously reported TSC2 association with ASD and with most other TAND manifestations.

Project description:BackgroundTuberous sclerosis complex (TSC) is a rare, genetic, multisystem disorder characterized by the growth of hamartomas in several organs, including the brain, kidneys, heart, eyes, and lungs. Even though over 90% of patients will have some form of TSC-associated neuropsychiatric disorder (TAND), there is an apparent lack of involvement of mental health professionals (MHPs) in the care of patients with TSC. The aim of this study was to determine the current level of TAND awareness in the TSC community and to identify possible barriers to effective multidisciplinary collaboration between MHPs and other healthcare providers (HCPs) in TAND management.MethodsAn electronic survey on current TSC and TAND management was conducted, targeting TSC caregivers/families, psychiatrists, neurologists, TSC specialists, and primary care physicians.ResultsThe invitation to participate in the survey was emailed to 659 HCPs and was disseminated through social media channels of patient advocacy groups. The survey was open for 4 months, with 359 responses collected. The majority of participants were TSC caregivers/families (73.3% of all responses). Of the 96 HCPs who participated, most were neurologists (61.5%) or TSC specialists (28.1%). Only 6 psychiatrists and 4 primary care physicians participated. Approximately half of patients have never had a neuropsychiatric assessment, and it was their caregivers/families who initiated the discussion of TAND with their providers. Almost 70% of TSC caregivers/families believed that psychiatric treatment could improve their quality of life. However, 54% of patients had difficulty obtaining psychiatric assessment. In turn, only 21% of HCPs believed that psychiatric therapy would help and 74% were concerned that their patients would be stigmatized by psychiatric referral.ConclusionsThis study focused on European healthcare systems suggests that current care for mental health issues in patients with TSC is inadequate, despite guideline recommendations for regular neuropsychiatric assessments. This appears to be due to a combination of gaps in diagnosis and surveillance, low frequency of psychiatric referrals, insufficient resources, and stigmatization of mental healthcare. There is a pressing need for further initiatives to study and address the mechanisms underlying the mental health treatment gap. The importance of MHP support must be recognized to optimize TSC management.

Project description:BackgroundObservational studies have identified various associations between neuroimaging alterations and neuropsychiatric disorders. However, whether such associations could truly reflect causal relations remains still unknown.ResultsHere, we leveraged genome-wide association studies (GWAS) summary statistics for (1) 11 psychiatric disorders (sample sizes varied from n = 9,725 to 1,331,010); (2) 110 diffusion tensor imaging (DTI) measurement (sample size n = 17,706); (3) 101 region-of-interest (ROI) volumes, and investigate the causal relationship between brain structures and neuropsychiatric disorders by two-sample Mendelian randomization. Among all DTI-Disorder combinations, we observed a significant causal association between the superior longitudinal fasciculus (SLF) and the risk of Anorexia nervosa (AN) (Odds Ratio [OR] = 0.62, 95 % confidence interval: 0.50 ~ 0.76, P = 6.4 × 10- 6). Similar significant associations were also observed between the body of the corpus callosum (fractional anisotropy) and Alzheimer's disease (OR = 1.07, 95 % CI: 1.03 ~ 1.11, P = 4.1 × 10- 5). By combining all observations, we found that the overall p-value for DTI - Disorder associations was significantly elevated compared to the null distribution (Kolmogorov-Smirnov P = 0.009, inflation factor λ = 1.37), especially for DTI - Bipolar disorder (BP) (λ = 2.64) and DTI - AN (λ = 1.82). In contrast, for ROI-Disorder combinations, we only found a significant association between the brain region of pars triangularis and Schizophrenia (OR = 0.48, 95 % CI: 0.34 ~ 0.69, P = 5.9 × 10- 5) and no overall p-value elevation for ROI-Disorder analysis compared to the null expectation.ConclusionsAs a whole, we show that SLF degeneration may be a risk factor for AN, while DTI variations could be causally related to some neuropsychiatric disorders, such as BP and AN. Also, the white matter structure might have a larger impact on neuropsychiatric disorders than subregion volumes.

Project description:Tuberous sclerosis complex (TSC) is a model disorder for understanding brain development because the genes that cause TSC are known, many downstream molecular pathways have been identified, and the resulting perturbations of cellular events are established. TSC, therefore, provides an intellectual framework to understand the molecular and biochemical pathways that orchestrate normal brain development. The TSC1 and TSC2 genes encode Hamartin and Tuberin which form a GTPase activating protein (GAP) complex. Inactivating mutations in TSC genes (TSC1/TSC2) cause sustained Ras homologue enriched in brain (RHEB) activation of the mammalian isoform of the target of rapamycin complex 1 (mTORC1). TOR is a protein kinase that regulates cell size in many organisms throughout nature. mTORC1 inhibits catabolic processes including autophagy and activates anabolic processes including mRNA translation. mTORC1 regulation is achieved through two main upstream mechanisms. The first mechanism is regulation by growth factor signaling. The second mechanism is regulation by amino acids. Gene mutations that cause too much or too little mTORC1 activity lead to a spectrum of neuroanatomical changes ranging from altered brain size (micro and macrocephaly) to cortical malformations to Type I neoplasias. Because somatic mutations often underlie these changes, the timing, and location of mutation results in focal brain malformations. These mutations, therefore, provide gain-of-function and loss-of-function changes that are a powerful tool to assess the events that have gone awry during development and to determine their functional physiological consequences. Knowledge about the TSC-mTORC1 pathway has allowed scientists to predict which upstream and downstream mutations should cause commensurate neuroanatomical changes. Indeed, many of these predictions have now been clinically validated. A description of clinical imaging and histochemical findings is provided in relation to laboratory models of TSC that will allow the reader to appreciate how human pathology can provide an understanding of the fundamental mechanisms of development.

Dataset Information

New insights into the pathogenesis and prevention of tuberous sclerosis-associated neuropsychiatric disorders (TAND).

Publications

New insights into the pathogenesis and prevention of tuberous sclerosis-associated neuropsychiatric disorders (TAND).

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