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The aim of this study is to identify differentially methylated regions (DMRs) in the genomes of a sample of cognitively healthy individuals and a sample of individuals with LOAD, all of them nonagenarians from Costa Rica.
In this study, we compared whole blood DNA methylation profiles of 32 individuals: 21 cognitively healthy and 11 with LOAD, using the Infinium MethylationEPIC BeadChip. First, we calculated the epigenetic age of the participants based on Horvath’s epigenetic clock. DMRcate and Bumphunter were used to identify DMRs. After in silico and knowledge-based filtering of the DMRs, we performed a methylation quantitative loci (mQTL) analysis (rs708727 and rs960603).
On average, the epigenetic age was 73 years in both groups, which represents a difference of over 20 years between epigenetic and chronological age in both affected and unaffected individuals. Methylation analysis revealed 11 DMRs between groups, which contain six genes and two pseudogenes. These genes are involved in cell cycle regulation, embryogenesis, synthesis of ceramides, and migration of interneurons to the cerebral cortex. One of the six genes is PM20D1, for which altered expression has been reported in LOAD. After genotyping previously reported mQTL SNPs for the gene, we found that average methylation in the PM20D1 DMR differs between genotypes for rs708727, but not for rs960603.
This work supports the possible role of PM20D1 in protection against AD, by showing differential methylation in blood of affected and unaffected nonagenarians. Our results also support the influence of genetic factors on PM20D1 methylation levels.
Bipolar disorder (BD) and obsessive compulsive disorder (OCD) are prevalent, comorbid, and disabling conditions, often characterized by early onset and chronic course. When comorbid, OCD and BD can determine a more pernicious course of illness, posing therapeutic challenges for clinicians. Available reports on prevalence and clinical characteristics of comorbidity between BD and OCD showed mixed results, likely depending on the primary diagnosis of analyzed samples.
We assessed prevalence and clinical characteristics of BD comorbidity in a large international sample of patients with primary OCD (n = 401), through the International College of Obsessive–Compulsive Spectrum Disorders (ICOCS) snapshot database, by comparing OCD subjects with vs without BD comorbidity.
Among primary OCD patients, 6.2% showed comorbidity with BD. OCD patients with vs without BD comorbidity more frequently had a previous hospitalization (p < 0.001) and current augmentation therapies (p < 0.001). They also showed greater severity of OCD (p < 0.001), as measured by the Yale–Brown Obsessive Compulsive Scale (Y-BOCS).
These findings from a large international sample indicate that approximately 1 out of 16 patients with primary OCD may additionally have BD comorbidity along with other specific clinical characteristics, including more frequent previous hospitalizations, more complex therapeutic regimens, and a greater severity of OCD. Prospective international studies are needed to confirm our findings.
An obsessive-compulsive disorder (OCD) subtype has been associated with streptococcal infections and is called pediatric autoimmune neuropsychiatric disorders associated with streptococci (PANDAS). The neuroanatomical characterization of subjects with this disorder is crucial for the better understanding of its pathophysiology; also, evaluation of these features as classifiers between patients and controls is relevant to determine potential biomarkers and useful in clinical diagnosis. This was the first multivariate pattern analysis (MVPA) study on an early-onset OCD subtype.
Fourteen pediatric patients with PANDAS were paired with 14 healthy subjects and were scanned to obtain structural magnetic resonance images (MRI). We identified neuroanatomical differences between subjects with PANDAS and healthy controls using voxel-based morphometry, diffusion tensor imaging (DTI), and surface analysis. We investigated the usefulness of these neuroanatomical differences to classify patients with PANDAS using MVPA.
The pattern for the gray and white matter was significantly different between subjects with PANDAS and controls. Alterations emerged in the cortex, subcortex, and cerebellum. There were no significant group differences in DTI measures (fractional anisotropy, mean diffusivity, radial diffusivity, and axial diffusivity) or cortical features (thickness, sulci, volume, curvature, and gyrification). The overall accuracy of 75% was achieved using the gray matter features to classify patients with PANDAS and healthy controls.
The results of this integrative study allow a better understanding of the neural substrates in this OCD subtype, suggesting that the anatomical gray matter characteristics could have an immune origin that might be helpful in patient classification.
Obsessive-compulsive disorder (OCD) is associated with variable risk of suicide and prevalence of suicide attempt (SA). The present study aimed to assess the prevalence of SA and associated sociodemographic and clinical features in a large international sample of OCD patients.
A total of 425 OCD outpatients, recruited through the International College of Obsessive-Compulsive Spectrum Disorders (ICOCS) network, were assessed and categorized in groups with or without a history of SA, and their sociodemographic and clinical features compared through Pearson’s chi-squared and t tests. Logistic regression was performed to assess the impact of the collected data on the SA variable.
14.6% of our sample reported at least one SA during their lifetime. Patients with an SA had significantly higher rates of comorbid psychiatric disorders (60 vs. 17%, p<0.001; particularly tic disorder), medical disorders (51 vs. 15%, p<0.001), and previous hospitalizations (62 vs. 11%, p<0.001) than patients with no history of SA. With respect to geographical differences, European and South African patients showed significantly higher rates of SA history (40 and 39%, respectively) compared to North American and Middle-Eastern individuals (13 and 8%, respectively) (χ2=11.4, p<0.001). The logistic regression did not show any statistically significant predictor of SA among selected independent variables.
Our international study found a history of SA prevalence of ~15% in OCD patients, with higher rates of psychiatric and medical comorbidities and previous hospitalizations in patients with a previous SA. Along with potential geographical influences, the presence of the abovementioned features should recommend additional caution in the assessment of suicide risk in OCD patients.
Obsessive compulsive disorder (OCD) showed a lower prevalence of cigarette smoking compared to other psychiatric disorders in previous and recent reports. We assessed the prevalence and clinical correlates of the phenomenon in an international sample of 504 OCD patients recruited through the International College of Obsessive Compulsive Spectrum Disorders (ICOCS) network.
Cigarette smoking showed a cross-sectional prevalence of 24.4% in the sample, with significant differences across countries. Females were more represented among smoking patients (16% vs 7%; p<.001). Patients with comorbid Tourette’s syndrome (p<.05) and tic disorder (p<.05) were also more represented among smoking subjects. Former smokers reported a higher number of suicide attempts (p<.05).
We found a lower cross-sectional prevalence of smoking among OCD patients compared to findings from previous studies in patients with other psychiatric disorders but higher compared to previous and more recent OCD studies. Geographic differences were found and smoking was more common in females and comorbid Tourette’s syndrome/tic disorder.
Molecular genetic studies of complex disorders require a number of parallel strategies. Many of the more familial psychiatric syndromes are highly prevalent and may represent a collection of a number of distinct genetic subtypes and possibly a number of nongenetic subtypes. A nongenetic form of illness may appear clinically indistinguishable from a genetic form. These nongenetic subtypes of a syndrome would be considered phenocopies. In this and the subsequent issue of CNS Spectrums, a number of papers are presented that review the current state of psychiatric genetics of major disorders. Clinical strategies to narrow phenotypes and better define study populations are paired with laboratory and statistical strategies to optimize both candidate gene and genome scanning methods.
In this issue, Kennedy and colleagues focus on a review of the genetics of schizophrenia, highlighting genome scans already completed and studies on special populations. Schindler and colleagues present a unique and efficient method for defining the homogeneity of a study population, surname analysis, and the importance of population selection in the design of genetic studies. Macedo and colleagues demonstrate the study of anticipation in bipolar mood disorder. Genetic anticipation is the observation of an earlier age of onset and greater disease severity in younger generations. This pattern has been associated with dynamic repeat expansions in the DNA in several neuropsychiatric disorders, and represents a good example of a unique genetic mechanism causing a unique phenotypic pattern. Nicolini and colleagues present work done to date on obsessive-compulsive disorder.
Genetic study holds potential for understanding the etiology of a number of serious psychiatric disorders. In the case of obsessive-compulsive disorder (OCD), many investigators agree that there is a strong genetic component to its development. In this article, we review the scientific evidence gleaned from different types of studies that has led to a better understanding of the nature of the inherited factors in OCD.
Systematic investigations indicate that some of the recognized psychiatric disorders can be identified among those with mental retardation due to chromosomal abnormalities. We report a psychotic patient with mild mental retardation (intelligence quotient: 68) and minor anomalies that had a chromosomal aberration not previously described in a psychotic patient. Our patient highlights the importance of the cytogenetic study in psychiatric patients with comorbid mental retardation or minor anomalies. In addition, her psychosis symptoms may be helpful to propose a new candidate gene for psychosis.
Obsessive-compulsive disorder (OCD) could be considered a neurodevelopmental disorder, from several lines of evidence. One of the most widely studied genes in these disorders is the apolipoprotein E gene, particularly allele 4. We analyzed for association among patients with OCD versus normal controls and cognitively impaired patients. There were no significant differences between OCD probands compared with population controls. However, the cognitively impaired group showed a higher frequency of allele apolipoprotein E gene compared with normal controls and patients with OCD.
The present study examined the psychobiological Temperament and Character model of personality on obsessive-compulsive disorder (OCD) patients, as well as the relation of temperament and/or character dimensions on the severity of obsessive-compubive symptoms.
Fifty-four subjects diagnosed with OCD, were assessed with the Temperament and Character Inventory, the Yale-Brown Obsessive-Compulsive scale and the Hamilton Rating Scales for depression and anxiety.
Compared with controls, OCD subjects displayed increased harm avoidance and lower self-directedness and cooperativeness. Low self-directedness and high Hamilton depression scores were associated with increased severity of obsessive-compulsive symptoms.
The Temperament and Character profile of OCD patients characterized in the present stud personality model and can be linked to some of their behavioral features. Furthermore, our data provides support of the influence that some personality traits may have on the severity of OCD symptoms.
The association between the APOE gene and Alzheimer's disease and other forms of dementia has been widely documented, but its relevance as a genetic risk factor in specific ethnic groups other than Caucasians in the United States and Europe is limited. The aim of this work was to describe the distribution of the APOE genotype in 80 subjects of Spanish origin, over 60 years old, who were institutionalized in the Spanish Hospital of Mexico City. Thirty-eight subjects who met the DSM-IV and ICD-10 criteria for Alzheimer's disease or vascular dementia and 42 controls without dementia underwent genotyping. APOE ε allele frequencies were as follows: for affected individuals, ε2, 7.9%, ε3, 69.7%, and ε4, 22.4%; for controls, ε2, 4.8%, ε3, 91.6%, and ε4, 3.6%. The higher frequency of the ε4 allele in the affected group (χ2 = 14.5; df = 4, p = .006) confirms an association between this APOE molecular variant and dementia in elderly Spaniards.
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