Brooke Sheppard

ADHD Prevalence and Association with Hoarding Behaviors in Childhood-Onset OCD

Background: It has been suggested that attention‐deficit hyperactivity disorder (ADHD) and obsessive–compulsive disorder (OCD), both neurodevelopmental disorders with onset in childhood, are highly comorbid, but previous studies examining ADHD and OCD comorbidity have been quite variable, partly because of inconsistency in excluding individuals with tic disorders. Similarly, ADHD has been postulated to be associated with hoarding although this potential relationship is largely methodologically unexplored. This study aimed to examine the prevalence of ADHD among individuals with childhood‐onset OCD but without comorbid tic disorders, as well as to examine the relationship between clinically significant hoarding behaviors (hoarding) and ADHD. Method: ADHD prevalence rates and the relationship between ADHD and hoarding were examined in 155 OCD‐affected individuals (114 probands and 41 relatives, age range 4–82 years) recruited for genetic studies and compared to pooled prevalence rates derived from previously published studies. Results: In total, 11.8% met criteria for definite ADHD, whereas an additional 8.6% had probable or definite ADHD (total=20.4%). In total, 41.9% of participants with ADHD also had hoarding compared to 29.2% of participants without ADHD. Hoarding was the only demographic or clinical variable independently associated with ADHD (odds ratio=9.54, P<0.0001). Conclusion: ADHD rates were elevated in this sample of individuals with childhood‐onset OCD compared to the general population rate of ADHD, and there was a strong association between ADHD and clinically significant hoarding behavior. This association is consistent with recent studies suggesting that individuals with hoarding may exhibit substantial executive functioning impairments and/or abnormalities, including attentional problems. Depression and Anxiety, 2010.

Genome-Wide Linkage Analysis of Obsessive-Compulsive Disorder Implicates Chromosome 1p36

BACKGROUND Obsessive-compulsive disorder (OCD) has a complex etiology involving both genetic and environmental factors. However, the genetic causes of OCD are largely unknown, despite the identification of several promising candidate genes and linkage regions. METHODS Our objective was to conduct genetic linkage studies of the type of OCD thought to have the strongest genetic etiology (i.e., childhood-onset OCD), in 33 Caucasian families with ≥2 childhood-onset OCD-affected individuals from the United States (n = 245 individuals with genotype data). Parametric and nonparametric genome-wide linkage analyses were conducted with Morgan and Merlin in these families using a selected panel of single nucleotide repeat polymorphisms from the Illumina 610-Quad Bead Chip. The initial analyses were followed by fine-mapping analyses in genomic regions with initial heterogeneity logarithm of odds (HLOD) scores of ≥2.0. RESULTS We identified five areas of interest (HLOD score ≥2) on chromosomes 1p36, 2p14, 5q13, 6p25, and 10p13. The strongest result was on chromosome 1p36.33-p36.32 (HLOD = 3.77, suggestive evidence for linkage after fine mapping). At this location, several of the families showed haplotypes co-segregating with OCD. CONCLUSIONS The results of this study represent the strongest linkage finding for OCD in a primary analysis to date and suggest that chromosome 1p36, and possibly several other genomic regions, may harbor susceptibility loci for OCD. Multiple brain-expressed genes lie under the primary linkage peak (approximately 4 megabases in size). Follow-up studies, including replication in additional samples and targeted sequencing of the areas of interest, are needed to confirm these findings and to identify specific OCD risk variants.

Medical Comorbidity of Attention-Deficit/Hyperactivity Disorder in US Adolescents

Understanding patterns of medical comorbidity in attention-deficit/hyperactivity disorder (ADHD) may lead to better treatment of affected individuals as well as aid in etiologic study of disease. This article provides the first systematic evaluation on the medical comorbidity of ADHD in a nationally representative sample (National Comorbidity Replication Survey–Adolescent Supplement; N = 6483) using formal diagnostic criteria. Survey-weighted odds ratios adjusted for demographics, additional medical, and mental disorders were calculated for associations between ADHD and medical conditions. Models adjusted for demographics revealed significantly increased odds of allergy, asthma, enuresis, headache/migraine, and serious stomach or bowel problems. After adjusting for comorbidity, across the medical conditions, enuresis and serious stomach problems were the strongest correlates of ADHD. These findings confirm the pervasive medical comorbidity of ADHD reported in previous clinical and community-based studies. The intriguing salience of enuresis and serious stomach or bowel conditions may also provide an important clue to multisystem involvement in ADHD.

Characteristics and comorbidity of ADHD sib pairs in the Central Valley of Costa Rica.

BACKGROUND While genetic epidemiological studies demonstrate a substantial degree of genetic predisposition for attention-deficit/hyperactivity disorder (ADHD), they also suggest that the genetics are complex and may differ between populations or ethnic groups. OBJECTIVE This study describes the phenomenology of siblings with ADHD from the genetically isolated population of the Central Valley of Costa Rica. METHODS Rates of Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV)-defined ADHD subtypes and comorbid conditions were calculated in a sample of 157 ADHD-affected children (probands and siblings) recruited for genetic studies using standardized approaches. Sib-sib comparisons and logistic regressions were conducted to identify significant patterns of concordance. RESULTS Combined-type ADHD (69.5%) was the most common subtype among probands, followed by the inattentive (27.4%), and hyperactive-impulsive (3.2%) subtypes. Anxiety disorders were prevalent (55.9%), as were disruptive behavior disorders (30.9%) and Tourette disorder (17.0%). Probands and siblings showed high sib-sib concordance for anxiety disorders. CONCLUSIONS ADHD in Costa Rica is similar in clinical and demographic characteristics to ADHD seen in other parts of the world, although the rates of co-occurring psychiatric disorders differ somewhat from those previously reported in Latin American samples. Comorbid anxiety is prevalent, with high rates of sib-sib concordance, and may represent a distinct, homogeneous subgroup suitable for genetic studies.