Hoarding in attention deficit hyperactivity disorder: Understanding the comorbidity

doi:10.1016/j.jocrd.2014.12.001

Journal of Obsessive-Compulsive and Related Disorders

Volume 4, January 2015, Pages 37-46

https://doi.org/10.1016/j.jocrd.2014.12.001 Get rights and content

Highlights

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Hoarding disorder has been associated with ADHD.
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Shared executive functioning deficits have been suggested to explain the comorbidity.
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A correlated liabilities model to understand the comorbidity is proposed.

Abstract

Hoarding disorder has a frequent co-occurrence with attention-deficit/hyperactivity disorder (ADHD). An accurate understanding of the comorbidity between hoarding disorder and ADHD remains unclear but is essential to inform appropriate assessment, prevention and treatment approaches. This paper will provide a review of potential comorbidity models and aetiological mechanisms implicated in both disorders in order to inform understanding of the nature of the comorbidity between hoarding disorder and ADHD. A correlated liabilities model is identified that implicates genetic, neurological, and executive functioning factors in the development and maintenance of hoarding symptoms in individuals with ADHD.

Introduction

Although ADHD and hoarding disorder commonly co-occur, relatively little is known about the aetiology of this comorbidity. Hoarding disorder is a new addition to the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5; American Psychiatric Association, 2013) and is defined as the difficulty discarding items due to urges to save possessions or distress when discarding; accumulation of items and cluttering of living spaces; and significant distress or impairment caused by these symptoms. Prior to its addition in the DSM-5, various terms were used to define hoarding disorder, such as compulsive hoarding (Frost & Hartl, 1996). However, the present paper will use the term ‘hoarding disorder’ to reflect the current DSM-5 designation but will note any important differences in individual studies׳ definitions of hoarding disorder.

Among the 2.3% of adults with hoarding disorder (Iervolino et al., 2009), approximately 28% have comorbid ADHD (Frost, Steketee, & Tolin, 2011). This population appears to experience greater deficits in functioning than those with hoarding disorder alone (Hall, Tolin, Frost, & Steketee, 2013), including more difficulties in activities of daily living, increased stress, and higher levels of domestic squalor (Hall et al., 2013). These deficits occur in addition to the hoarding-related impairments of compromised safety (Frost, Steketee, & Williams, 2000), reduced quality of life (Palermo et al., 2011), increased employment and housing difficulties (Saxena et al., 2011), and severe medical issues, including higher risk of arthritis, diabetes, obesity, and stroke compared to individuals without hoarding disorder (Tolin, Frost, Steketee, Gray, & Fitch, 2008).

The severe potential consequences of comorbid hoarding disorder in individuals with ADHD and the high association between the two disorders point to the importance of developing a greater understanding of the features involved in the co-occurrence of these disorders, particularly the causal and maintenance factors. It has recently been suggested that shared executive functioning deficits may explain the comorbidity between ADHD and hoarding disorder (Fullana et al., 2013, Hall et al., 2013). However, to date, no study has investigated this possibility in a sample of individuals with ADHD with comorbid hoarding disorder. The potential role of executive functioning as a mechanism linking ADHD and hoarding disorder therefore remains unknown.

The present review aims to synthesise the current literature to develop a model that may be used to understand the comorbidity between hoarding disorder and ADHD. To do this, several potential comorbidity models will be explored. The correlated liabilities model will be evaluated by providing a critical analysis of possible evidence of a shared genetic, neurological, and executive functioning aetiology of hoarding disorder among adults with ADHD. Such an analysis may inform understanding of the mechanisms of hoarding symptoms in this population and may highlight clinical implications, including prevention and treatment approaches.

Section snippets

Overlap between ADHD and hoarding disorder

There is substantial evidence for an association between ADHD and hoarding disorder. For example, in an assessment of comorbidity in adults with hoarding disorder, 27.8% were found to have comorbid inattentive ADHD, while 13.7% had hyperactive ADHD (Frost et al., 2011). Furthermore, Sheppard et al. (2010) found that 21.9% of adults with hoarding disorder had comorbid ADHD. In contrast, it appears from a meta-analysis of prevalence rates of ADHD using DSM-IV diagnostic criteria that ADHD only

Genetic factors

The contribution of genetic components and neural dysfunction associated with ADHD and hoarding disorder has led to a consensus that the aetiology of both disorders includes substantial biological factors. For example, in a comprehensive study of 5022 pairs of twins, Iervolino et al. (2009) reported that genetic factors explained approximately 50% of the variance in hoarding disorder. Samuels, Bienvenu III, et al. (2007) examined hoarding symptoms in 132 relatives of individuals with OCD and

The role of executive functions

Executive functions can be broadly described as higher-order capacities of self-regulation that are instrumental to independent, future-oriented intentional behaviours (Barkley, 2001). These include numerous actions such as planning, inhibition, flexibility, organisation, working memory, updating, and mental set-shifting, among others (Ardila, 2008, Barkley, 2001, Chan et al., 2008, Miyake et al., 2000). Deficits in these functions are typically associated with abnormal activation in, or damage

Summary

This review of empirical findings has shown support for the correlated liabilities model in explaining the comorbidity between ADHD and hoarding disorder. The key executive functions of spatial working memory, planning, and inhibition have been specifically implicated in the hoarding disorder profile. A review of these functions in ADHD has found that adults with ADHD may be particularly vulnerable to difficulties in each of these areas. Despite these findings, and the suggestions that

Clinical implications

The findings of this review provide support for a shared vulnerability between hoarding disorder and ADHD, including executive functioning difficulties, genetic vulnerability, and neurological impairments. This has several implications for current treatment approaches. Firstly, hoarding disorder has an early age of onset (Tolin, Meunier, Frost, & Steketee, 2010) with a severe symptom progression (Ayers, Saxena, Golshan, & Wetherell, 2010) that results in particularly disruptive consequences for

Suggestions for future research

The research reviewed has focused on the influence of genetic factors, neurological impairments, and executive functioning weaknesses on hoarding disorder and ADHD alone; however the nature of these factors in individuals with ADHD and comorbid hoarding disorder remains unknown. It may be helpful for future research to determine the extent to which individuals with comorbid ADHD and hoarding disorder have similar or different genetic compositions, neurological, and executive functioning

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Hoarding mysteries Jack would appreciate
2022, Journal of Behavior Therapy and Experimental Psychiatry
Citation Excerpt :
He could sometimes talk aloud to himself to better stay on task, but often strayed from his own self-instructions when new projects occurred to him. Lynch and colleagues (Lynch, McGillivray, Moulding, & Y Byrne, 2015) have suggested that genetic, neurological and executive functioning problems are shared vulnerabilities that underlie both hoarding and attention deficit disorders. Given the hypothesized vulnerabilities in the CBT model for HD that typically include cognitive processing problems and especially decision-making difficulties, we are surprised that attention deficit is not more characteristic of HD.
Hoarding disorder (HD) is a multifaceted problem that presents challenges both for understanding its dimensions and for developing effective treatments. We are grateful to have known Dr. Stanley J. Rachman and his incredibly thoughtful approach to clinical psychology and research on anxiety, obsessive-compulsive disorders (OCD) and their treatment. His work has helped set the stage for our own efforts to study this challenging condition. The discussion below reviews a range of mysteries we and others have encountered in working with people who exhibit HD symptoms. Of particular interest to us are questions about biological vulnerabilities like heritability and the high rate of concurrent health problems and whether hoarded objects might serve as safety signals that protect people from traumatic life events. We are curious about the attachment process in HD and whether attachment to objects is related to early parental experiences that affect self-concept. We raise questions about the several information processing problems often seen in people with HD – attention focusing, memory, and associative responses to objects and information. Raising many questions are observations about strong emotional attachments to objects and multiple reasons given for saving them, as well as what sometimes appears to be remarkable aesthetic appreciation and creative interest in objects. Emotions in HD seem to range more widely than in some psychological disorders as both positive and negative reactions appear to reinforce excessive acquisition and difficulty discarding. Clutter blindness may be an effort to avoid confrontation with overwhelming clutter in the home. Finally, we comment on difficulty achieving more positive outcomes following a carefully designed cognitive and behavioral treatment for HD and encourage the next generation of researchers to follow in Jack Rachman's footsteps as they try to unravel these mysteries.
Elevated levels of hoarding in ADHD: A special link with inattention
2022, Journal of Psychiatric Research
Hoarding Disorder (HD) is under recognised and under-treated. Though HD develops by early adulthood, patients present only later in life, resulting in research based largely on samples of predominantly older females. Whilst formerly associated with Obsessive-Compulsive Disorder (OCD), it is now recognised that individuals with HD often have inattention symptoms reminiscent of Attention Deficit/Hyperactivity Disorder (ADHD). Here, we investigated HD in adults with ADHD. Patients in an ADHD clinic (n = 88) reported on ADHD, HD and OCD-related symptoms, and compared with age, gender and education matched controls (n = 90). Findings were assessed independently in an online UK sample to verify replication using a dimensional approach (n = 220). Clinically significant hoarding symptoms were found in ∼20% versus 2% of ADHD and control groups, respectively, with those with hoarding being on average in their thirties and with approximately half being male. Greater hoarding severity was noted even in the remaining patients compared with controls (d = 0.89). Inattention was the only significant statistical predictor of hoarding severity in patients. Similarly, inattention, alongside depression and anxiety were the greatest predictors of hoarding in the independent sample where 3.2% identified as having clinically significant hoarding. Patients with ADHD had a high frequency of hoarding symptoms, which were specifically linked to inattention. HD should be routinely assessed in individuals with ADHD, as they do not typically disclose associated difficulties, despite these potentially leading to impaired everyday functioning. Research in HD should also investigate adults with ADHD, who are younger and with a greater prevalence of males than typical HD samples.
Hoarding disorder and co-occurring medical conditions: A systematic review
2021, Journal of Obsessive-Compulsive and Related Disorders
Citation Excerpt :
Other potential third variable factors hypothesized to account for a link between HD and medical conditions include those related to information processing and executive functioning difficulties (e.g., impulsivity, attention deficit hyperactivity disorder). Extant research highlights associations between HD and various executive functioning and information processing concerns (Ayers et al., 2013; Frost & Hartl, 1996; Grisham & Barlow, 2005; Grisham et al., 2007; Mataix-Cols et al., 2011; McMillan et al., 2012; Tolin, Kiehl, et al., 2008; Tolin & Villavicencio, 2011), such as difficulties with impulsivity/impulse control disorders (de Mattos et al., 2018; Frost et al, 2001, 2011; Rasmussen et al., 2013; Steketee & Frost, 2003; Timpano et al., 2012) and ADHD (Frost et al., 2011; Lynch et al., 2015; Tolin & Villavicencio, 2011). Given that individuals with ADHD tend to have heightened health risks (e.g., obesity, smoking), injury (e.g., fractures, sprains, open wounds), and medical conditions (e.g., asthma, inflammation, allergic diseases, autoimmune disorders, respiratory infections, epilepsy) similar to those seen in HD (Chen et al., 2017; Merrill et al., 2009; Nigg, 2013; Salpekar & Mishra, 2014; Zhou et al., 2017), such executive functioning/information processing clinical presentations may confer additional risk for the development of HD, resultant excessive clutter, and related health concerns.
Hoarding disorder (HD) is relatively common within the community but remains notoriously difficult to treat, a phenomenon that could be related, at least in part, to the number of medical diagnoses typically co-occurring with the condition. In an effort to examine the potential link between treatment ambivalence in hoarding and certain co-occurring medical diagnoses, what follows is a comprehensive review of the empirical literature addressing HD, physical health, and medical conditions. A systematic search of scholarly databases (i.e., PubMed, PsycInfo, Google Scholar) identified nine relevant articles for review. Broadly, the research suggests that individuals with hoarding behaviors suffer from poorer health than those without hoarding tendencies, although clinically significant hoarding and levels of physical health were defined differently across studies. The review also identifies clinical correlates that could account for the link between HD and co-occurring medical conditions, such as obesity, impulsivity, executive dysfunction, and emotion regulation. Preliminary bidirectional hypotheses of HD and co-occurring medical conditions are presented in an effort to guide future research and theory-building in this area. Finally, limitations, directions for future research, and clinical implications are also discussed.
Psychological and electrophysiological indices of inattention in hoarding
2018, Psychiatry Research
Individuals with elevated hoarding symptoms report elevated symptoms of ADHD and these symptoms are related to impaired daily functioning. Neuropsychological studies have found specific deficits in attention, and a recent review of attentional data from numerous hoarding studies concluded that inattention likely represents an etiological factor in hoarding, rather than a comorbidity. Our study aimed to examine which symptoms of ADHD, inattention or hyperactivity, are related to hoarding symptom severity, and whether individuals with hoarding symptoms display a neurophysiological marker of poor attention (Theta/Beta Ratio; THBR) that might explain these associations. The THBR indexes theta power relative to beta power in the frontal cortex and is often atypical in individuals with ADHD. We hypothesised that individuals would report more severe problems with inattention and would exhibit an elevated theta/beta ratio relative to a healthy control group. We also predicted that any relationship between hoarding and inattention would be independent of anxiety and depression symptoms. 17 hoarding-symptomatic participants and 16 healthy control participants completed self-report measures relating to ADHD, hoarding and general psychopathology, and then underwent resting measures of electroencephalography (EEG). Individuals with hoarding symptoms reported greater difficulties with inattention and hyperactivity, however they did not exhibit an elevated theta/beta ratio. When taking into account recent anxiety and depression, only inattention predicted hoarding symptom severity. Further investigations may help clarify this association and help inform attention-based treatments for hoarding.
Phenomenology of hoarding in children with comorbid attention-deficit/hyperactivity disorder (ADHD): The perceptions of parents
2017, Comprehensive Psychiatry
Citation Excerpt :
It has been suggested that the core ADHD symptoms and the executive functioning deficits common among those with ADHD may help to explain the high comorbidity of hoarding symptoms [10–12]. This may indicate support for the multiformity model of comorbidity [13], which suggests that hoarding symptoms may be an epiphenomena of ADHD, rather than arising from a separate etiological mechanism (for discussion, see [14]). However, this model is yet to be systematically evaluated in the comorbidity between ADHD and hoarding disorder.
Individuals with ADHD and comorbid hoarding disorder are vulnerable to severe consequences from hoarding symptoms. Despite this, and the early onset of hoarding disorder, the nature of hoarding symptoms in children with comorbid ADHD is unknown. We therefore explored the phenomenology of hoarding symptoms among ten 8–12 year olds with ADHD and clinically significant hoarding symptoms through parental perceptions. Parents completed in-depth semi-structured interviews. The data was analyzed using Interpretative Phenomenological Analysis. Six superordinate themes were identified: emotional distress; parental avoidance and accommodating behaviors; family impacts of hoarding; excessive acquisition and saving; executive functioning; parental insight and intervention. In contrast to previous suggestions that emotional distress was not associated with hoarding in ADHD, these findings highlight that emotional distress appeared to be core to the hoarding disorder profile of the present sample of children with ADHD. This has important implications for health practitioners who may consider conceptualizing, assessing, and treating hoarding symptoms in children with comorbid ADHD using a cognitive behavioral model of hoarding disorder.
The relationship between self-reported and objective neuropsychological impairments in patients with hoarding disorder
2016, Journal of Obsessive-Compulsive and Related Disorders
Although hoarding disorder (HD) is characterized by self- and clinician-reported difficulties with cognitive functioning, studies of neuropsychological performance have yielded little evidence of consistent, clinical-level cognitive impairments. The aim of this study was to quantify this inconsistency and to examine whether this pattern is unique to HD. Fifty-three adults (20 with HD, 19 with obsessive compulsive disorder (OCD) and minimal hoarding symptoms, and 14 with OCD and a high degree of hoarding symptoms (OCD-H)) completed self-report and objective neuropsychological tests of inhibition, attention, and memory. The three groups differed significantly on self-reported attention and memory deficits, with the HD group reporting greater difficulties. However, the groups performed comparably on objective neuropsychological tests of inhibition, attention, immediate and delayed nonverbal memory, and immediate verbal memory. The OCD-H group demonstrated a greater rate of impairment on a test of delayed verbal memory. The HD group was characterized by lower concordance rates between self-report and objective memory impairment. The groups did not differ significantly in concordance rates for self-report and objective measures of attention and inhibition. Understanding the discrepancy between self-report and objective neuropsychological measures may help to better characterize the role of cognitive processes in HD.

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Hoarding in attention deficit hyperactivity disorder: Understanding the comorbidity

Highlights

Abstract

Introduction

Section snippets

Overlap between ADHD and hoarding disorder

Genetic factors

The role of executive functions

Summary

Clinical implications

Suggestions for future research

Neuroimaging

Brain and Cognition

American Journal of Geriatric Psychiatry

Biological Psychiatry

Biological Psychiatry

Trends in Cognitive Sciences

Archives of Clinical Neuropsychology

Biological Psychiatry

Journal of Psychiatric Research

Journal of Obsessive–Compulsive and Related Disorders

Behaviour Research and Therapy

Behaviour Research and Therapy

Journal of Obsessive–Compulsive and Related Disorders

Behaviour Research and Therapy

Behaviour Research and Therapy

Journal of the American Academy of Child and Adolescent Psychiatry

Neurobiology of Aging

Biological Psychiatry

Cognitive Psychology

Psychiatry Research

Behaviour Research and Therapy

Comprehensive Psychiatry

Journal of Obsessive–Compulsive and Related Disorders

Behaviour Research and Therapy

Journal of Psychiatric Research

Behaviour Research and Therapy

Psychiatry Research

Diagnosis, assessment, and comorbidity in psychosocial treatment research

Journal of Abnormal Child Psychology

Working memory deficits in adults with attention-deficit/hyperactivity disorder (ADHD): an examination of central executive and storage/rehearsal processes

Journal of Abnormal Psychology

Genetic susceptibility to obsessive–compulsive hoarding: the contribution of neurotrophic tyrosine kinase receptor type 3 gene

Genes, Brain & Behavior

Executive function and the frontal lobes: a meta-analytic review

Neuropsychology Review

Diagnostic and statistical manual of mental disorders

To discard or not to discard: The neural basis of hoarding symptoms in obsessive–compulsive disorder

Molecular Psychiatry

A neural basis for collecting behaviour in humans

Brain

Therapist and patient perspectives on cognitive-behavioral therapy for older adults with hoarding disorder: a collective case study

Aging and Mental Health

Age at onset and clinical features of late life compulsive hoarding

Geriatric Psychiatry

Executive functioning in older adults with hoarding disorder

International Journal of Geriatric Psychiatry

The executive functions and self-regulation: an evolutionary neuropsychological perspective

Neuropsychology Review

Anterior cingulate cortex and symptom severity in attention-deficit/hyperactivity disorder

Journal of Abnormal Psychology

Cognitive functioning in compulsive hoarding

Journal of Anxiety Disorders

To act or not to act, that׳s the problem: primarily inhibition difficulties in adult ADHD

Neuropsychology

Effects of subtype of attention-deficit/hyperactivity disorder in adults on lateralized readiness potentials during a go/no-go choice reaction time task

Journal of Abnormal Psychology

Executive functioning differences between adults with attention deficit hyperactivity disorder and autistic spectrum disorder in initiation, planning, and strategy formation

Autism

The neurobiological link between OCD and ADHD

ADHD Attention Deficit and Hyperactivity Disorders

Cognitive deficit caused by regional depletion of dopamine in prefrontal cortex of rhesus monkey

Science

Heritability and the comorbidity of attention deficit hyperactivity disorder with behavioral disorders and executive function deficits: a preliminary investigation

Developmental Neuropsychology

Toward systems neuroscience of ADHD: a meta-analysis of 55 fMRI studies

The American Journal of Psychiatry

Constructing constructs for psychopathology: the NIMH research domain criteria

The Journal of Abnormal Psychology

Normative data from the Cantab. I: development of executive function over the lifespan