Ages of Onset of Mood and Anxiety Disorders in Fragile X Premutation Carriers

The effect of college degree attainment on neurodegenerative symptoms in genetically at-risk women

Using longitudinal data, the present study examined the association between college degree attainment and the manifestation of neurodegenerative symptoms among women (n = 93) at elevated genetic risk. The neurodegenerative symptoms investigated in this study are due to FXTAS (Fragile X-associated Tremor/Ataxia Syndrome), a condition with onset after age 50. Those at risk for FXTAS have a mutation of a single gene found on the X chromosome. FXTAS is characterized by intention tremor, gait ataxia, executive function deficits, memory issues, and neuropathy. College degree attainment has been shown to provide neuroprotective effects in the general population, delaying the development of neurodegenerative conditions such as Alzheimer's disease. For this reason, college degree attainment is a potentially salient resource for those at risk of FXTAS. The results of the present research indicated significantly more severe FXTAS symptoms in women who did not attain a college degree as compared with those who were college graduates, although the two groups were similar in age, genetic risk, household income, health behaviors, and general health problems. Furthermore, symptoms in those who did not attain a college degree worsened over the 9-year study period at a significantly faster rate than the college graduates. The association between college degree attainment and FXTAS symptoms was significantly mediated by depression, which was lower among the graduates than those who did not attain a college degree. Thus, the present research is an example of how a sociodemographic factor can mitigate neurodegenerative conditions in genetically at-risk adults.

Women with Fragile X-associated Tremor/Ataxia Syndrome

BACKGROUND

Fragile X-associated tremor and ataxia syndrome (FXTAS) is a late-onset neurodegenerative disorder linked to the FMR1 premutation.

OBJECTIVES

FXTAS in women is far less common than in men, and this study represents the largest sample reported to date.

METHODS

A total of 53 female premutation carriers with FXTAS (meanage, 66.83 years; FXTAS stages 2-5) and 55 age-matched and demographic background-matched control participants (meanage, 61.94 years) underwent a comprehensive molecular, physiological, neuropsychological, and psychiatric assessment.

RESULTS

The large sample of female premutation carriers showed a wide range of variability of clinical signs and symptom progression. The imaging results showed a middle cerebellar peduncles sign in only 6 patients; another symptom included high-signal intensity in the splenium of the corpus callosum, and diffuse cerebral deep white matter changes (e.g., in the pons) are more common. The rate of psychiatric disorders, especially depression, is higher than in the general population. There is a clear impairment in executive functioning and fine motor skills in connection with a higher FXTAS stage.

CONCLUSIONS

The manifestation of FXTAS symptoms in female carriers can be diverse with a milder phenotype and a lower penetrance than those observed in male premutation carriers. The middle cerebellar peduncles sign is present in only a small percentage of the sample, and we propose that the imaging criteria for FXTAS in women need to be expanded.

Fragile X associated neuropsychiatric disorders in a male without FXTAS

Fragile X syndrome (FXS) is the most common inherited cause of intellectual disability and autism spectrum disorder. In most cases, it is due to an expansion of the CGG triplet to more than 200 repeats within the promoter region of the FMR1 gene. In the premutation (PM) the trinucleotide is expanded to 55-200 repeats. PM carriers can present with disorders associated with the PM including fragile X-associated tremor/ataxia syndrome (FXTAS) and fragile X-associated ovarian insufficiency (FXPOI). Recently fragile X-associated neuropsychiatric disorders (FXAND) was proposed as an umbrella term to include the neuropsychiatric disorders that are more prevalent in PM carriers compared to the general population such as anxiety, depression, chronic fatigue, alcohol abuse, and psychosis, among others. The patient in our study was evaluated by a team of clinicians from the University del Valle in Cali who traveled to Ricaurte, a Colombian town known for being a genetic geographic cluster of FXS. A detailed medical history was collected and complete physical, neurological and psychiatric evaluations were performed in addition to molecular and neuroradiological studies. We report the case of a 78-year-old man, PM carrier, without FXTAS whose main clinical presentation consists of behavioral changes and psychosis. Brain imaging revealed white matter lesions in the periventricular region and mild cerebral atrophy. Although anxiety and depression are the most common neuropsychiatric manifestations in PM carriers, it is important to perform a complete psychiatric evaluation since some patients may present with behavioral changes and psychosis.

[Fragile X associated tremor/ataxia syndrome: its clinical presentation, pathology, and treatment]

The fragile X associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disease associated with the repetition of CGG triplets (55-200 CGG repetitions) in the FMR1 gene. The premutation of the FMR1 gene, contrasting with the full mutation (more than 200 CGG repetitions), presents an increased production of messenger and a similar or slightly decreased production of FMRP protein. FXTAS affects 40% of men and 16% of women carriers of the premutation. It presents with a wide constellation of neurological signs such as intention tremor, cerebellar ataxia, parkinsonism, executive function deficits, peripheral neuropathy and cognitive decline leading to dementia among others. In this review, we present what is currently known about the molecular mechanism, the radiological findings and the pathology, as well as the complexity of the diagnosis and management of FXTAS.

Fragile X-Associated Neuropsychiatric Disorders (FXAND)

Fragile X syndrome (FXS) is caused by the full mutation (>200 CGG repeats) in the Fragile X Mental Retardation 1 (FMR1) gene. It is the most common inherited cause of intellectual disability (ID) and autism. This review focuses on neuropsychiatric disorders frequently experienced by premutation carriers with 55 to 200 CGG repeats and the pathophysiology involves elevated FMR1 mRNA levels, which is different from the absence or deficiency of fragile X mental retardation protein (FMRP) seen in FXS. Neuropsychiatric disorders are the most common problems associated with the premutation, and they affect approximately 50% of individuals with 55 to 200 CGG repeats in the FMR1 gene. Neuropsychiatric disorders in children with the premutation include anxiety, ADHD, social deficits, or autism spectrum disorders (ASD). In adults with the premutation, anxiety and depression are the most common problems, although obsessive compulsive disorder, ADHD, and substance abuse are also common. These problems are often exacerbated by chronic fatigue, chronic pain, fibromyalgia, autoimmune disorders and sleep problems, which are also associated with the premutation. Here we review the clinical studies, neuropathology and molecular underpinnings of RNA toxicity associated with the premutation. We also propose the name Fragile X-associated Neuropsychiatric Disorders (FXAND) in an effort to promote research and the use of fragile X DNA testing to enhance recognition and treatment for these disorders.

Fragile X-Associated Diminished Ovarian Reserve and Primary Ovarian Insufficiency from Molecular Mechanisms to Clinical Manifestations

Fragile X syndrome (FXS), is caused by a loss-of-function mutation in the FMR1 gene located on the X-chromosome, which leads to the most common cause of inherited intellectual disability in males and the leading single-gene defect associated with autism. A full mutation (FM) is represented by more than 200 CGG repeats within the FMR1 gene, resulting in FXS. A FM is inherited from women carrying a FM or a premutation (PM; 55–200 CGG repeats) allele. PM is associated with phenotypes distinct from those associated with FM. Some manifestations of the PM are unique; fragile-X-associated tremor/ataxia syndrome (FXTAS), and fragile-X-associated primary ovarian insufficiency (FXPOI), while others tend to be non-specific such as intellectual disability. In addition, women carrying a PM may suffer from subfertility or infertility. There is a need to elucidate whether the impairment of ovarian function found in PM carriers arises during the primordial germ cell (PGC) development stage, or due to a rapidly diminishing oocyte pool throughout life or even both. Due to the possibility of expansion into a FM in the next generation, and other ramifications, carrying a PM can have an enormous impact on one’s life; therefore, preconception counseling for couples carrying the PM is of paramount importance. In this review, we will elaborate on the clinical manifestations in female PM carriers and propose the definition of fragile-X-associated diminished ovarian reserve (FXDOR), then we will review recent scientific findings regarding possible mechanisms leading to FXDOR and FXPOI. Lastly, we will discuss counseling, preventative measures and interventions available for women carrying a PM regarding different aspects of their reproductive life, fertility treatment, pregnancy, prenatal testing, contraception and fertility preservation options.

Reduced vagal tone in women with the FMR1 premutation is associated with FMR1 mRNA but not depression or anxiety

Background

Autonomic dysfunction is implicated in a range of psychological conditions, including depression and anxiety. The fragile X mental retardation-1 (FMR1) premutation is a common genetic mutation that affects ~1:150 women and is associated with psychological vulnerability. This study examined cardiac indicators of autonomic function among women with the FMR1 premutation and control women as potential biomarkers for psychological risk that may be linked to FMR1.

Methods

Baseline inter-beat interval and respiratory sinus arrhythmia (a measure of parasympathetic vagal tone) were measured in 35 women with the FMR1 premutation and 28 controls. The women completed anxiety and depression questionnaires. FMR1 genetic indices (i.e., CGG repeat, quantitative FMRP, FMR1 mRNA, activation ratio) were obtained for the premutation group.

Results

Respiratory sinus arrhythmia was reduced in the FMR1 premutation group relative to controls. While depression symptoms were associated with reduced respiratory sinus arrhythmia among control women, these variables were unrelated in the FMR1 premutation. Elevated FMR1 mRNA was associated with higher respiratory sinus arrhythmia.

Conclusions

Women with the FMR1 premutation demonstrated autonomic dysregulation characterized by reduced vagal tone. Unlike patterns observed in the general population and in study controls, vagal activity and depression symptoms were decoupled in women with the FMR1 premutation, suggesting independence between autonomic regulation and psychopathological symptoms that is atypical and potentially specific to the FMR1 premutation. The association between vagal tone and mRNA suggests that molecular variation associated with FMR1 plays a role in autonomic regulation.

Clinical and molecular correlates in fragile X premutation females

The prevalence of the fragile X premutation (55-200 CGG repeats) among the general population is relatively high, but there remains a lack of clear understanding of the links between molecular biomarkers and clinical outcomes. In this study we investigated the correlations between molecular measures (CGG repeat size, FMR1 mRNA, FMRP expression levels, and methylation status at the promoter region and in FREE2 site) and clinical phenotypes (anxiety, obsessive compulsive symptoms, depression and executive function deficits) in 36 adult premutation female carriers and compared to 24 normal control subjects. Premutation carriers reported higher levels of obsessive compulsive symptoms, depression, and anxiety, but demonstrated no significant deficits in global cognitive functions or executive function compared to the control group. Increased age in carriers was significantly associated with increased anxiety levels. As expected, FMR1 mRNA expression was significantly correlated with CGG repeat number. However, no significant correlations were observed between molecular (including epigenetic) measures and clinical phenotypes in this sample. Our study, albeit limited by the sample size, establishes the complexity of the mechanisms that link the FMR1 locus to the clinical phenotypes commonly observed in female carriers suggesting that other factors, including environment or additional genetic changes, may have an impact on the clinical phenotypes. However, it continues to emphasize the need for assessment and treatment of psychiatric problems in female premutation carriers.

Psychiatric disorders among women with the fragile X premutation without children affected by fragile X syndrome

Several studies have demonstrated increased rates of anxiety and depressive disorders among female carriers of the fragile X premutation. However, the majority of these studies focused on mothers of children with fragile X syndrome, who experience higher rates of parenting stress that may contribute to the emergence of these disorders. The present study compared psychiatric symptom presentation (utilizing measures of current symptoms and lifetime DSM-IV Axis I disorders) in 24 female carriers without affected children (mean age = 32.1 years) to 26 non-carrier women from the community (mean age = 30.5 years). We also examined the association between CGG repeat size (adjusted for X activation ratio) and mRNA, with severity of psychiatric symptoms. Women with the premutation reported significantly elevated symptoms of anxiety, depression, interpersonal sensitivity, obsessive-compulsiveness, and somatization relative to controls during the past week. Carriers had significantly higher rates of lifetime social phobia (42.3%) compared to controls (12.5%); however, this comparison did not remain significant after multiple comparison adjustment. Rates of other psychiatric disorders were not significantly elevated relative to controls, though it should be noted that lifetime rates among controls were much higher than previously published population estimates. Although the sample is relatively small, the study of this unique cohort suggests the premutation confers risk for mood and anxiety disorders independent of the stress of parenting children with FXS. Screening for psychiatric disorders in women with the premutation, even before they become parents, is important and highly encouraged. © 2016 Wiley Periodicals, Inc.

Endocrine Dysfunction in Female FMR1 Premutation Carriers: Characteristics and Association with Ill Health

Female FMR1 premutation carriers (PMC) have been suggested to be at greater risk of ill health, in particular endocrine dysfunction, compared to the general population. We set out to review the literature relating to endocrine dysfunction, including premature ovarian insufficiency (POI), in female PMCs, and then to consider whether endocrine dysfunction in itself may be predictive of other illnesses in female PMCs. A systematic review and pilot data from a semi-structured health questionnaire were used. Medline, Embase, and PsycInfo were searched for papers concerning PMCs and endocrine dysfunction. For the pilot study, self-reported diagnoses in females were compared between PMCs with endocrine dysfunction (n = 18), PMCs without endocrine dysfunction (n = 14), and individuals without the premutation (n = 15). Twenty-nine papers were identified in the review; the majority concerned POI and reduced fertility, which are consistently found to be more common in PMCs than controls. There was some evidence that thyroid dysfunction may occur more frequently in subgroups of PMCs and that those with endocrine difficulties have poorer health than those without. In the pilot study, PMCs with endocrine problems reported higher levels of fibromyalgia (p = 0.03), tremor (p = 0.03), headache (p = 0.01) and obsessive-compulsive disorder (p = 0.009) than either comparison group. Further larger scale research is warranted to determine whether female PMCs are at risk of endocrine disorders other than those associated with reproduction and whether endocrine dysfunction identifies a high-risk group for the presence of other health conditions.

Risk Factors for Cognitive Impairment in Fragile X-Associated Tremor/Ataxia Syndrome

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disease with motor, psychiatric, and cognitive manifestations that occurs in carriers of the fragile X mental retardation 1 ( FMR1) gene premutations. This was a retrospective chart review of 196 individuals (127 men and 69 women) with FXTAS. Forty-six (23%) participants were cognitively impaired, of whom 19 (10%) had dementia. Risk factors for dementia were examined (CGG repeat size; alcohol, benzodiazepine, and opioid use; diabetes; hyperlipidemia; hypertension; hypothyroidism; obesity; sleep apnea; surgeries with general anesthesia; depression; family history of dementia). Thirteen individuals with FXTAS and dementia were then compared to 13 cognitively intact individuals matched on age, gender, and FXTAS stage. CGG repeat size was significantly higher (mean = 98.5, standard deviation [SD] = 22.2) in the dementia group, compared to the cognitively intact group (mean = 81.6, SD = 11.5; P = .0256). These results show that CGG repeat size is a risk factor for FXTAS dementia.

Clinically significant psychiatric symptoms among male carriers of the fragile X premutation, with and without FXTAS, and the mediating influence of executive functioning

OBJECTIVES

To clarify the neuropsychiatric phenotype of fragile X-associated tremor/ataxia syndrome (FXTAS), and assess the extent to which it is mediated by the dysexecutive syndrome that is a major feature of the disorder.

METHODS

We examined the prevalence of clinically meaningful psychiatric symptoms among male carriers of the fragile X premutation, with and without FXTAS, in comparison with men with a normal allele. Measures included the Neuropsychiatric Inventory (NPI), Symptom Checklist-90-R (SCL-90-R), and the Behavioral Dyscontrol Scale, a measure of executive functioning. Between-group differences were evaluated using logistic regression, followed by a mediation analysis with ordinary least squares regression to assess the contribution of dysexecutive syndrome to the observed psychiatric domains.

RESULTS

Men with FXTAS showed higher rates of clinically significant symptoms overall and in specific domains: somatization, obsessive compulsive, depression, anxiety, psychoticism, agitation/aggression, apathy/indifference, irritability, and nighttime behavior problems. Post hoc analyses suggested that findings of psychoticism among men with FXTAS may be associated with participants' accurate acknowledgment of cognitive and physical dysfunction, rather than reflecting psychosis. Asymptomatic carriers showed no evidence of clinically significant psychiatric symptoms, but when all carriers were compared with men having a normal FMR1 allele, executive function deficits were found to mediate scores in several domains on both NPI and SCL-90-R.

CONCLUSIONS

Building on prior research, the results provide evidence that the psychiatric phenotype for men includes clinically meaningful depression, hostility, and irritability, in association with behavioral and attentional disinhibition. It is likely that these problems reflect the effects of impaired executive functioning.

Fragile X-associated tremor/ataxia syndrome - features, mechanisms and management

Many physicians are unaware of the many phenotypes associated with the fragile X premutation, an expansion in the 5' untranslated region of the fragile X mental retardation 1 (FMR1) gene that consists of 55-200 CGG repeats. The most severe of these phenotypes is fragile X-associated tremor/ataxia syndrome (FXTAS), which occurs in the majority of ageing male premutation carriers but in fewer than 20% of ageing women with the premutation. The prevalence of the premutation is 1 in 150-300 females, and 1 in 400-850 males, so physicians are likely to see people affected by FXTAS. Fragile X DNA testing is broadly available in the Western world. The clinical phenotype of FXTAS at presentation can vary and includes intention tremor, cerebellar ataxia, neuropathic pain, memory and/or executive function deficits, parkinsonian features, and psychological disorders, such as depression, anxiety and/or apathy. FXTAS causes brain atrophy and white matter disease, usually in the middle cerebellar peduncles, the periventricular area, and the splenium and/or genu of the corpus callosum. Here, we review the complexities involved in the clinical management of FXTAS and consider how targeted treatment for these clinical features of FXTAS will result from advances in our understanding of the molecular mechanisms that underlie this neurodegenerative disorder. Such targeted approaches should also be more broadly applicable to earlier forms of clinical involvement among premutation carriers.

Current research, diagnosis, and treatment of fragile X-associated tremor/ataxia syndrome

Fragile X-associated tremor/ataxia syndrome (FXTAS) is caused by a premutation CGG-repeat expansion in the 5'UTR of the fragile X mental retardation 1 (FMR1) gene. The classical clinical manifestations include tremor, cerebellar ataxia, cognitive decline and psychiatric disorders. Other less frequent features are peripheral neuropathy and autonomic dysfunction. Cognitive decline, a form of frontal subcortical dementia, memory loss and executive function deficits are also characteristics of this disorder. In this review, we present an expansion of recommendations for genetic testing for adults with suspected premutation disorders and provide an update of the clinical, radiological and molecular research of FXTAS, as well as the current research in the treatment for this intractable complex neurodegenerative genetic disorder.

Associated features in females with an FMR1 premutation

Changes in the fragile X mental retardation 1 gene (FMR1) have been associated with specific phenotypes, most specifically those of fragile X syndrome (FXS), fragile X tremor/ataxia syndrome (FXTAS), and fragile X primary ovarian insufficiency (FXPOI). Evidence of increased risk for additional medical, psychiatric, and cognitive features and conditions is now known to exist for individuals with a premutation, although some features have been more thoroughly studied than others. This review highlights the literature on medical, reproductive, cognitive, and psychiatric features, primarily in females, that have been suggested to be associated with changes in the FMR1 gene. Based on this review, each feature is evaluated with regard to the strength of evidence of association with the premutation. Areas of need for additional focused research and possible intervention strategies are suggested.

Towards an Understanding of Neuropsychiatric Manifestations in Fragile X Premutation Carriers

Fragile X-associated disorders (FXD) are a group of disorders caused by expansion of non-coding CGG repeat elements in the fragile X (FMR1) gene. One of these disorders, fragile X syndrome (FXS), is the most common heritable cause of intellectual disability, and is caused by large CGG repeat expansions (>200) resulting in silencing of the FMR1 gene. An increasingly recognized number of neuropsychiatric FXD have recently been identified that are caused by 'premutation' range expansions (55-200). These disorders are characterized by a spectrum of neuropsychiatric manifestations ranging from an increased risk of neurodevelopmental, mood and anxiety disorders to neurodegenerative phenotypes such as the fragile X-associated tremor ataxia syndrome (FXTAS). Here, we review advances in the clinical understanding of neuropsychiatric disorders in premutation carriers across the lifespan and offer guidance for the detection of such disorders by practicing psychiatrists and neurologists.

Abnormal semantic processing in females with fragile X-associated tremor/ataxia syndrome

Fragile X-associated tremor/ataxia syndrome (FXTAS), a neurodegenerative disorder, affects fragile X (FMR1) gene premutation carriers in late life. Studies have shown cognitive impairments in FXTAS including executive dysfunction, working memory and visuospatial deficits. However, less is known about cognition in females with FXTAS. Thus, we examined semantic processing and verbal memory in female FXTAS patients with event-related potentials (ERPs) and neuropsychological testing. Sixty-one females (34 FXTAS, Mage  = 62.7; 27 controls, Mage  = 60.4) were studied with 32-channel ERPs during a category judgment task in which semantically congruous (50%) and incongruous items were repeated approximately 10-140 seconds later. N400 and P600 amplitude data were submitted to analysis of covariance. Neuropsychological testing demonstrated lower performance in verbal learning and executive function in females with FXTAS. Event-related potential analyses showed a significant reduction of the N400 congruity effect (incongruous - congruous) in the FXTAS group. The N400 congruity effect reduction in females with FXTAS was mainly due to increased N400 amplitude to congruous new words. No significant abnormalities of the N400 repetition effect or the P600 repetition effect were found, indicating preserved implicit memory and verbal memory, respectively, in females with FXTAS. The decreased N400 congruity effect suggests abnormal semantic expectancy and/or semantic network disorganization in female FXTAS patients. The enhanced N400 amplitude to congruous new words may reflect decreased cognitive flexibility among FXTAS women, making access to less typical category exemplar words more difficult.

Advances in clinical and molecular understanding of the FMR1 premutation and fragile X-associated tremor/ataxia syndrome

Fragile X syndrome, the most common heritable form of cognitive impairment, is caused by epigenetic silencing of the fragile X (FMR1) gene owing to large expansions (>200 repeats) of a non-coding CGG-repeat element. Smaller, so-called premutation expansions (55-200 repeats) can cause a family of neurodevelopmental phenotypes (attention deficit hyperactivity disorder, autism spectrum disorder, seizure disorder) and neurodegenerative (fragile X-associated tremor/ataxia syndrome [FXTAS]) phenotypes through an entirely distinct molecular mechanism involving increased FMR1 mRNA production and toxicity. Results of basic cellular, animal, and human studies have helped to elucidate the underlying RNA toxicity mechanism, while clinical research is providing a more nuanced picture of the range of clinical manifestations. Advances of knowledge on both mechanistic and clinical fronts are driving new approaches to targeted treatment, but two important necessities are emerging: to define the extent to which the mechanisms contributing to FXTAS also contribute to other neurodegenerative and medical disorders, and to redefine FXTAS in view of its differing presentations and associated features.

Fragile X-associated tremor/ataxia syndrome (FXTAS): pathology and mechanisms

Since its discovery in 2001, our understanding of fragile X-associated tremor/ataxia syndrome (FXTAS) has undergone a remarkable transformation. Initially characterized rather narrowly as an adult-onset movement disorder, the definition of FXTAS is broadening; moreover, the disorder is now recognized as only one facet of a much broader clinical pleiotropy among children and adults who carry premutation alleles of the FMR1 gene. Furthermore, the intranuclear inclusions of FXTAS, once thought to be a CNS-specific marker of the disorder, are now known to be widely distributed in multiple non-CNS tissues; this observation fundamentally changes our concept of the disease, and may provide the basis for understanding the diverse medical problems associated with the premutation. Recent work on the pathogenic mechanisms underlying FXTAS indicates that the origins of the late-onset neurodegenerative disorder actually lie in early development, raising the likelihood that all forms of clinical involvement among premutation carriers have a common underlying mechanistic basis. There has also been great progress in our understanding of the triggering event(s) in FXTAS pathogenesis, which is now thought to involve sequestration of one or more nuclear proteins involved with microRNA biogenesis. Moreover, there is mounting evidence that mitochondrial dysregulation contributes to the decreased cell function and loss of viability, evident in mice even during the neonatal period. Taken together, these recent findings offer hope for early interventions for FXTAS, well before the onset of overt disease, and for the treatment of other forms of clinical involvement among premutation carriers.