Heritability of hoarding symptoms across adolescence and young adulthood: A longitudinal twin study

Hoarding Disorder: The Current Evidence in Conceptualization, Intervention, and Evaluation

Hoarding disorder is characterized by difficulty parting with possessions due to strong urges to save the items, leading to the excessive accumulation of items. High clutter levels result in varied personal, social, and legal consequences. Specialized treatments, including individual, virtual, and group cognitive and behavioral therapies, community-based interventions, and peer support approaches have shown preliminary effectiveness. Animal, attachment, and neurobiological models are expanding our understanding of the etiological bases of the disorder. Specialized populations such as children, older adults, and involuntary patients are highlighted as requiring special consideration for intervention and risk mitigation. Directions for future research are identified.

Association between attachment and hoarding behavior: Mediation of anthropomorphism and moderation of hoarding beliefs among Chinese adolescents

The impact of insecure attachment on hoarding behavior (HB) has been supported by empirical evidence. However, scant literature has focused on how anthropomorphism (attributing human-like traits, characteristics, or emotions to nonhuman objects) and hoarding beliefs (motivations for ownership) affect the relationship between insecure attachment and HB, especially among Chinese adolescents. Using a cross-sectional study, we reserved 903 participants (561 males, 342 females, M = 20.20, SD = 1.85, age range = 18-24 years) to complete self-report questionnaires about close relationships, anthropomorphism, saving beliefs, and saving inventory to investigate the mediating role of anthropomorphism and the moderating role of hoarding beliefs in the relationship between insecure attachment and HB. Attachment anxiety and avoidance had a positive relationship with HB, and anthropomorphism is a mediating factor in the association between attachment anxiety and HB. In addition, hoarding beliefs moderated the relationship between attachment anxiety and HB. This study further elaborated on the relationships between insecure attachment, anthropomorphism, hoarding beliefs, and HB, which might shed some light on adolescent clinical interventions.

Meta-analysis of genome-wide association studies of hoarding symptoms in 27,537 individuals

Hoarding Disorder (HD) is a mental disorder characterized by persistent difficulties discarding or parting with possessions, often resulting in cluttered living spaces, distress, and impairment. Its etiology is largely unknown, but twin studies suggest that it is moderately heritable. In this study, we pooled phenotypic and genomic data from seven international cohorts (N = 27,537 individuals) and conducted a genome wide association study (GWAS) meta-analysis of parent- or self-reported hoarding symptoms (HS). We followed up the results with gene-based and gene-set analyses, as well as leave-one-out HS polygenic risk score (PRS) analyses. To examine a possible genetic association between hoarding symptoms and other phenotypes we conducted cross-trait PRS analyses. Though we did not report any genome-wide significant SNPs, we report heritability estimates for the twin-cohorts between 26-48%, and a SNP-heritability of 11% for an unrelated sub-cohort. Cross-trait PRS analyses showed that the genetic risk for schizophrenia and autism spectrum disorder were significantly associated with hoarding symptoms. We also found suggestive evidence for an association with educational attainment. There were no significant associations with other phenotypes previously linked to HD, such as obsessive-compulsive disorder, depression, anxiety, or attention-deficit hyperactivity disorder. To conclude, we found that HS are heritable, confirming and extending previous twin studies but we had limited power to detect any genome-wide significant loci. Much larger samples will be needed to further extend these findings and reach a "gene discovery zone". To move the field forward, future research should not only include genetic analyses of quantitative hoarding traits in larger samples, but also in samples of individuals meeting strict diagnostic criteria for HD, and more ethnically diverse samples.

Hoarding Disorder: Development in Conceptualization, Intervention, and Evaluation

Hoarding disorder is characterized by difficulty parting with possessions because of strong urges to save the items. Difficulty discarding often includes items others consider to be of little value and results in accumulation of a large number of possessions that clutter the home. Cognitive-behavioral therapy (CBT) with exposure and response prevention and selective serotonin reuptake inhibitor medications traditionally used to treat obsessive-compulsive disorder are generally not efficacious for people with hoarding problems. A specialized CBT approach for hoarding has shown progress in reaching treatment goals and has been modified to be delivered in group, peer-facilitated, and virtual models. Research on hoarding remains in the early phases of development. Animal, attachment, and genetic models are expanding. Special populations, such as children, older adults, and people who do not voluntarily seek treatment need special consideration for intervention. Community-based efforts aimed at reducing public health and safety consequences of severe hoarding are needed.

Brain Functional Connectivity Correlates of Subclinical Obsessive-Compulsive Symptoms in Healthy Children

OBJECTIVE

Commonly observed subclinical obsessive-compulsive symptoms in healthy children may predispose to obsessive-compulsive disorder (OCD). Therefore, investigating the underlying neurobiology may be relevant to identify alterations in specific brain circuits potentially accounting for clinical heterogeneity in OCD without the confounding effects of clinical samples. We analyzed the brain correlates of different obsessive-compulsive symptoms in a large group of healthy children using functional connectivity measures.

METHOD

We evaluated 227 healthy children (52% girls; mean [SD] age 9.71 [0.86] years; range, 8-12.1 years). Participants underwent clinical assessment with the Obsessive-Compulsive Inventory-Child Version and a resting-state functional magnetic resonance imaging examination. Total and symptom-specific severity were correlated with voxelwise global functional connectivity degree values. Significant clusters were then used as seeds of interest in seed-to-voxel analyses. Modulating effects of age and sex were also assessed.

RESULTS

Global functional connectivity of the left ventral putamen and medial dorsal thalamus correlated negatively with total obsessive-compulsive symptom severity. Seed-to-voxel analyses revealed specific negative correlations from these clusters with limbic, sensorimotor, and insular regions in association with obsessing, ordering, and doubt-checking symptoms, respectively. Hoarding symptoms were associated with negative correlations between the left medial dorsal thalamus and a widespread pattern of regions, with such associations modulated by sex and age.

CONCLUSION

Our findings concur with prevailing neurobiological models of OCD on the importance of cortico-striato-thalamo-cortical dysfunction to account for symptom severity. Notably, we showed that changes in cortico-striato-thalamo-cortical connectivity are present at subclinical stages, which may result in an increased vulnerability for OCD. Moreover, we mapped different symptom dimensions onto specific cortico-striato-thalamo-cortical circuit attributes.

Genetics of OCD and Related Disorders; Searching for Shared Factors

Obsessive compulsive disorder (OCD) and several other obsessive-compulsive related disorders (OCRDs) including hoarding disorder, body dysmorphic disorder (BDD), skin picking disorder, trichotillomania and the newly arising public health conditions of online gaming and gambling disorders, under the umbrella of Problematic Usage of the Internet (PUI), not only share some common phenotypes, but there is evidence to suggest share some genetic risk factors. The simple fact that these disorders segregate within families points to this notion. However, the current data are still scarce. This chapter focuses on identifying the shared genetic factors. To address this question, a systematic review of the literature investigating genetic findings in OCD and OCRDs including PUI was conducted, with a focus on their genetic similarities. Greater knowledge of the specific genetic risks shared among OCRDs would be expected to open new avenues in the understanding of the biological mechanisms causing the development of these phenotypes, as well as provide opportunities to develop new animal and cellular models testing new therapy avenues.

The developmental origins of hoarding disorder in adolescence: a longitudinal clinical interview study following an epidemiological survey

Hoarding disorder (HD) is hypothesized to originate in childhood/adolescence but little is known about the presentation of hoarding symptoms in youth and their natural history. In this longitudinal study, we tracked and conducted in-depth psychiatric interviews with twins who participated in an epidemiological survey and screened positive on a measure of hoarding symptoms at age 15. Twins screening positive for clinically significant hoarding symptoms at age 15 (n = 42), their co-twins (n = 33), a group of screen negative twins (n = 49), and their parents underwent a clinical assessment a median of 3 years after the initial screening. The assessment included psychiatric screening, hoarding symptoms and cognitions, in-home or photographic assessment of clutter levels, parental accommodation and familial burden. None of the participants had significant levels of clutter at follow-up and thus did not meet strict criteria for HD. However, twins meeting partial criteria (i.e., DSM-5 criteria A and B) for HD (n = 28) had more psychiatric disorders and scored significantly higher on all measures of hoarding symptoms including researcher-rated levels of clutter in their homes, compared to twins who did not meet partial criteria for HD (n = 46). As currently defined in DSM-5, HD may be rare in young people. A non-negligible proportion of young people who were screen positive on hoarding symptoms at age 15 had substantial hoarding symptoms and other psychopathology at follow-up. Whether and how many of these individuals will develop full-blown HD is unknown but the results offer unique insights about the probable origins of HD in adolescence.

Serotonin system genes and hoarding with and without other obsessive-compulsive traits in a population-based, pediatric sample: A genetic association study

BACKGROUND

Hoarding, originally only considered a symptom of obsessive-compulsive disorder (OCD), is now categorized as a separate disorder in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). We studied candidate serotonergic genes and the distinctness of hoarding in children and adolescents and hypothesized that unique gene variants would be associated with hoarding alone.

METHODS

We examined obsessive-compulsive (OC) traits, including hoarding, in a total of 5,213 pediatric participants in the community. We genotyped candidate serotonin genes (5-HTTLPR polymorphism in SLC6A4 for 2,018 individuals and single nucleotide polymorphisms [SNPs] across genes SLC6A4, HTR2A, and HTR1B for 4,711 individuals). In a previous study conducted by our group in the same sample, we identified a significant association between 5-HTTLPR and hoarding in males. In this study, we examined hoarding more closely by testing the association between serotonin gene variants and hoarding traits with and without other accompanying OC traits.

RESULTS

The [L_G +S] variant in 5-HTTLPR was significantly associated with hoarding alone in males (p-value of 0.009). There were no significant findings for 5-HTTLPR in females. There were no significant findings after correction for multiple comparisons using SNP array data, but top SNP findings suggested that variation downstream of HTR1B may be implicated in hoarding alone in females.

CONCLUSIONS

Our results suggest specific serotonin gene variants are associated with hoarding traits alone, differing between sexes. Top findings are in line with our former study, suggesting that individuals with hoarding alone were driving previous results. Our paper supports hoarding disorder's new designation.

Pharmacotherapy for Hoarding Disorder: How did the Picture Change since its Excision from OCD?

This brief review deals with the various issues that contributed to the creation of the new Diagnostic and Statistical Manual condition of hoarding disorder (HD) and attempts at reviewing its pharmacotherapy. It appears that after the newly founded diagnosis appeared in the literature as an autonomous entity, distinct from obsessive-compulsive disorder, drug trials are not being conducted and the disorder is left in the hands of psychotherapists, who on their part, report fair results in some core dimensions of HD. The few trials on HD specifically regard the serotonin-noradrenaline reuptake inhibitor venlafaxine, and, possibly due to the suggestion of a common biological background of HD with attention-deficit/hyperactivity disorder, the psychostimulant methylphenidate and the noradrenaline reuptake inhibitor atomoxetine. For all these drugs, positive results have been reported, but the evidence level of these studies is low, due to small samples and non-blind designs. Regretfully, there are currently no future studies aiming at seriously testing drugs in HD.

The Swedish Twin Registry: Content and Management as a Research Infrastructure

The Swedish Twin Registry functions as research infrastructure containing information on 216,258 twins born between 1886 and 2015, of whom 86,199 pairs have zygosity determined by DNA, an intrapair similarity algorithm, or being of opposite sex. In essence, practically all twins alive and currently 9 years or older have been invited for participation and donation of DNA on which genomewide single nucleotide polymorphisms array genotyping has been performed. Content, management and alternatives for future improvements are discussed.

Recent Advances in Research on Hoarding

PURPOSE OF REVIEW

The purpose of the following paper is to review recent literature trends and findings in hoarding disorder (HD). Our goal is to highlight recent research on etiology, associated features, and empirically based treatments.

RECENT FINDINGS

Recent literature has added support for cognitive differences as a risk factor for HD; however, there is evidence that individuals with HD may overestimate their level of cognitive impairment. Several associated features have been highlighted in recent studies, including emotion regulation, intolerance of uncertainty and distress intolerance, and attachment. Finally, several psychotherapeutic treatments for hoarding have been recently validated, including group-based therapy and treatments using the cognitive-behavioral model. Although recent research demonstrates that hoarding can be effectively treated with available psychotherapeutic modalities, the effectiveness of current treatments is not as robust as that for other psychiatric disorders and more work is needed in treatment precision.

Relevance of hoarding behavior and the traits of developmental disorders among university students: a self-reported assessment study

Background

Previous studies have shown that hoarding behavior usually starts at a subclinical level in early adolescence and gradually worsens; however, a limited number of studies have examined the prevalence of hoarding behavior and its association with developmental disorders in young adults. The aims of this study were to estimate the prevalence of hoarding behavior and to identify correlations between hoarding behavior and developmental disorder traits in university students.

Methods

The study participants included 801 university students (616 men, 185 women) who completed questionnaires (ASRS: Adult ADHD Self-Report Scale version 1.1, AQ16: Autism-Spectrum Quotient with 16 items, and CIR: Clutter Image Rating).

Results

Among 801 participants, 27 (3.4%) exceeded the CIR cut-off score. Moreover, the participants with hoarding behavior had a significantly higher percentage of ADHD traits compared to participants without hoarding behavior (HB(+) vs HB(−), 40.7% vs 21.7%). In addition, 7.4% of HB(+) participants had autism spectrum disorder (ASD) traits, compared to 4.1% of HB(−) participants. A correlation analysis revealed that the CIR composite score had a stronger correlation with the ASRS inattentive score than with the hyperactivity/impulsivity score (CIR composite vs ASRS IA, r = 0.283; CIR composite vs ASRS H/I, r = 0.147).

Conclusions

The results showed a high prevalence of ADHD traits in the university students with hoarding behavior. Moreover, we found that the hoarding behavior was more strongly correlated with inattentive symptoms rather than with hyperactivity/impulsivity symptoms. Our results support the concept of a common pathophysiology behind hoarding behavior and ADHD in young adults.

Prevalence and heritability of body dysmorphic symptoms in adolescents and young adults: a population-based nationwide twin study

BACKGROUND

Body dysmorphic disorder (BDD) usually begins during adolescence but little is known about the prevalence, etiology, and patterns of comorbidity in this age group. We investigated the prevalence of BDD symptoms in adolescents and young adults. We also report on the relative importance of genetic and environmental influences on BDD symptoms, and the risk for co-existing psychopathology.

METHODS

Prevalence of BDD symptoms was determined by a validated cut-off on the Dysmorphic Concerns Questionnaire (DCQ) in three population-based twin cohorts at ages 15 (n = 6968), 18 (n = 3738), and 20-28 (n = 4671). Heritability analysis was performed using univariate model-fitting for the DCQ. The risk for co-existing psychopathology was expressed as odds ratios (OR).

RESULTS

The prevalence of clinically significant BDD symptoms was estimated to be between 1 and 2% in the different cohorts, with a significantly higher prevalence in females (1.3-3.3%) than in males (0.2-0.6%). The heritability of body dysmorphic concerns was estimated to be 49% (95% CI 38-54%) at age 15, 39% (95% CI 30-46) at age 18, and 37% (95% CI 29-42) at ages 20-28, with the remaining variance being due to non-shared environment. ORs for co-existing neuropsychiatric and alcohol-related problems ranged from 2.3 to 13.2.

CONCLUSIONS

Clinically significant BDD symptoms are relatively common in adolescence and young adulthood, particularly in females. The low occurrence of BDD symptoms in adolescent boys may indicate sex differences in age of onset and/or etiological mechanisms. BDD symptoms are moderately heritable in young people and associated with an increased risk for co-existing neuropsychiatric and alcohol-related problems.

Psychometric Evaluation of a Revised Scoring Approach for the Children's Saving Inventory in a Canadian Sample of Youth With Obsessive-Compulsive Disorder

The Children's Saving Inventory (CSI) was introduced in 2011 and is the first parent-rated questionnaire specifically designed to measure the severity of hoarding symptoms in youth. To date, however, no replication studies of the CSI have been published. Additionally, the total CSI score includes several items measuring acquisition, a behavioural dimension that has since been excluded from DSM-5's hoarding disorder criteria. Given these limitations, the primary goal of the present study was to test a modified, DSM-5-consistent, total score of the CSI. Because a confirmatory factor analysis did not support the 2011 four-factor model of the CSI, we reviewed the original CSI and excluded all acquisition items. An exploratory factor analysis yielded a strong three-factor solution (difficulty discarding, Clutter, and distress/impairment) with good reliability and validity for a 15-item version of the CSI. Overall, our results support the use of the 15-item CSI in youth with OCD.

Animal hoarding: The challenge for mental health, law enforcement, and animal welfare professionals

Animal hoarding has been considered a significant problem by animal welfare and law enforcement professionals for over a century. However, it has only been recognized as an indication of a mental disorder in the last decade. I review the different forms that animal hoarding can take and the current understanding of the prevalence, demographics and possible etiology of this disorder. Conventional animal cruelty laws have often been inadequate to respond to animal hoarding cases until they reach levels that may involve serious harm to animals and people. I document how prosecution of such cases can be difficult and often does not adequately consider the mental health issues underlying the problem or the high likelihood of recidivism. Attempts to solve these problems by enacting new laws specifically addressing animal hoarding have been controversial and ineffective. I explore new approaches that coordinate a variety of community resources in response to hoarding cases that offer the best opportunity to respond to both the human and animal problems associated with animal hoarding.

Gene × Environment Interaction in Developmental Disorders: Where Do We Stand and What's Next?

Although the field of psychiatry has witnessed the proliferation of studies on Gene × Environment (G×E) interactions, still limited is the knowledge we possess of G×E interactions regarding developmental disorders. In this perspective paper, we discuss why G×E interaction studies are needed to broaden our knowledge of developmental disorders. We also discuss the different roles of hazardous versus self-generated environmental factors and how these types of factors may differentially engage with an individual's genetic background in predicting a resulting phenotype. Then, we present examplar studies that highlight the role of G×E in predicting atypical developmental trajectories as well as provide insight regarding treatment outcomes. Supported by these examples, we explore the need to move beyond merely examining statistical interactions between genes and the environment, and the motivation to investigate specific genetic susceptibility and environmental contexts that drive developmental disorders. We propose that further parsing of genetic and environmental components is required to fully understand the unique contribution of each factor to the etiology of developmental disorders. Finally, with a greater appreciation of the complexities of G×E interaction, this discussion will converge upon the potential implications for clinical and translational research.

Predictors of treatment outcome and attrition in adults with hoarding disorder

While a number of hoarding disorder-specific therapeutic interventions have been developed over recent years, hoarding disorder (HD) remains difficult to treat. The purpose of this investigation is to inform HD treatment efforts by examining factors that influence treatment attrition and treatment response. Secondary data analysis of baseline and post-treatment data from two previously published psychotherapy treatment studies for hoarding were performed to identify predictors of hoarding symptom improvement and treatment attrition in 106 adults with HD. No demographic variables were associated with symptom improvement or treatment attrition. However, higher levels of avoidant coping (i.e., self-distraction combined with behavioral disengagement) significantly predicted symptom improvement. The maintenance stage of change along with high readiness for change also significantly predicted symptom improvement. Participants who dropped from treatment had significantly higher baseline levels of denial and clutter, both of which independently predicted treatment attrition. The findings from this study suggest that emotion-related constructs, such as managing stress and motivation for change, may play an important role in patients' response to and participation in HD treatment.