Structural brain network connectivity in trichotillomania (hair-pulling disorder)

Neuroimaging studies suggest involvement of frontal, striatal, limbic and cerebellar regions in trichotillomania, an obsessive-compulsive related disorder. However, findings regarding the underlying neural circuitry remains limited and inconsistent. Graph theoretical analysis offers a way to identify structural brain networks in trichotillomania. T1-weighted MRI scans were acquired in adult females with trichotillomania (n = 23) and healthy controls (n = 16). Graph theoretical analysis was used to investigate structural networks as derived from cortical thickness and volumetric FreeSurfer output. Hubs, brain regions with highest connectivity in the global network, were identified, and group differences were determined. Regions with highest connectivity on a regional level were also determined. There were no differences in small-worldness or other network measures between groups. Hubs in the global network of trichotillomania patients included temporal, parietal, and occipital regions (at 2SD above mean network connectivity), as well as frontal and striatal regions (at 1SD above mean network connectivity). In contrast, in healthy controls hubs at 2SD represented different frontal, parietal and temporal regions, while at 1SD hubs were widespread. The inferior temporal gyrus, involved in object recognition as part of the ventral visual pathway, had significantly higher connectivity on a global and regional level in trichotillomania. The study included women only and sample size was limited. This study adds to the trichotillomania literature on structural brain network connectivity. Our study findings are consistent with previous studies that have implicated somatosensory, sensorimotor and frontal-striatal circuitry in trichotillomania, and partially overlap with structural connectivity findings in obsessive-compulsive disorder.

Characteristics of trichotillomania and excoriation disorder across the lifespan

Trichotillomania (hair-pulling disorder) and excoriation (skin-picking) disorder are body-focused repetitive behaviors, which often first present in adolescence and cause distress and impairment into adulthood. Few studies have examined the clinical characteristics of the co-occurrence of these conditions across the lifespan. We examined cross-sectional survey responses collected from April 2018-February 2020 to evaluate the relationship between trichotillomania, excoriation disorder, and their co-occurrence. Responses from individuals with trichotillomania (n = 50), excoriation disorder (n = 52), and both conditions (n = 50) ages 4-67 years old were compared for co-occurring conditions and current symptoms. Self-report measures of hair-pulling and skin-picking severity and subtypes were assessed. Gender, race, and co-occurring conditions were generally similarly distributed across the three groups with high rates of self-reported anxiety (63-82%), depression (34-50%), obsessive-compulsive disorder (16-29%), and attention-deficit/hyperactivity disorder (12-32%). Among individuals with both trichotillomania and excoriation disorder, significant positive correlations were observed between hair-pulling and skin-picking severity scores as well as hair-pulling and skin-picking subtypes. Hair-pulling and skin-picking severity peaked at the transition from adolescence to adulthood and hair-pulling/skin-picking styles appeared to shift across the lifespan. Our results support several similarities between trichotillomania and excoriation disorder, providing new insight into the clinical characteristics of these conditions.

Cognitive Inflexibility in OCD and Related Disorders

Cognitive inflexibility is suggested by the hallmark symptoms of obsessive-compulsive disorder (OCD), namely the occurrence of repetitive thoughts and/or behaviours that persist despite being functionally impairing and egodystonic to the individual. As well as being implied by the top-level symptoms, cognitive inflexibility in OCD, and some related conditions, has also been objectively quantified in case-control studies using computerised cognitive tasks. This chapter begins by considering the objective measurement of different aspects of cognitive flexibility using neuropsychological paradigms, with a focus on neural and neurochemical substrates. It moves on to conduct a systematic review and meta-analysis of findings from a widely deployed flexibility task: the Intra-Dimensional/Extra-Dimensional Set-Shift Task (IDED). By pooling data from 11 studies (335 OCD patients and 311 controls), we show that Extra-Dimensional (ED) shift deficits are a robust and reproducible finding (effect size medium-large) in OCD across the literature, and that this deficit is not attributable to group differences in age or IQ. The OCD ED deficit is then discussed in terms of dysfunction of fronto-striatal pathways (as exemplified, for example, by functional connectivity data), and the putative role of different neurotransmitters. We consider evidence that impaired ED shifting constitutes a candidate vulnerability marker (or 'endophenotype') for OCD. The available literature is then surveyed as to ED findings in other obsessive-compulsive (OC) related disorders (e.g. hoarding, body-dysmorphic disorder, and trichotillomania), as well as in non-OC disorders (schizophrenia and anxiety symptoms in general). Lastly, we consider more recent, emerging developments in the quantification of compulsivity using cognitive tasks and questionnaires, as well as key directions for future research, including the need to refine compulsivity and its composite cognitive processes.

Scared and surrounded by clutter: The influence of emotional reactivity

BACKGROUND

Home visits can improve treatment outcomes for hoarding disorder, but factors influencing the success of home visits remain unknown. As home visits expose individuals to clutter and fear, the present study examined the effect that fear and emotional reactivity have on the relationship between clutter and discarding behaviour.

METHODS

Participants with at least subclinical discarding problems (n = 143) were asked to save or discard personal possessions of varying value following an emotional induction that took place in either a tidy or cluttered context. Participants also completed questionnaires assessing hoarding severity, emotional state, and emotional reactivity, as defined by one's sensitivity, persistence, and intensity of reactions to emotional stimuli.

RESULTS

As expected, participants discarded more items in the presence of clutter and when feeling fearful. However, emotional reactivity moderated the relations between environmental context, acute emotional state, and discarding. Low sensitivity, low persistence, and high emotional intensity negatively influenced discarding in the cluttered context. When feeling fearful, low dispositional emotional intensity negatively influenced discarding in the tidy context.

LIMITATIONS

Individuals in the tidy environment reported higher levels of fear and anxiety than individuals in the cluttered environment after the fear induction. These differences could have contributed to the difference noted between the two contexts when examining the effect of emotional intensity tendencies.

CONCLUSIONS

Providing treatment in an environment more representative of the cluttered home can improve discarding or at the very least give therapists a more accurate picture of what clients do in the context that matters most.

Shame in the obsessive compulsive related disorders: a conceptual review

BACKGROUND

Theoretical and anecdotal support for the role of shame in obsessive compulsive related disorders (OCRDs) is prominent. Developing our understanding of shame׳s role in OCRDs is important to building knowledge about this new diagnostic category. This review aims to consolidate our understanding of shame in each OCRD, through summarizing existing clinical, conceptual, and empirical work.

METHODS

We provide an overview of shame, its measurement considerations, and a full review of 110 articles addressing shame in OCRDs.

RESULTS

General shame and shame about having a mental illness are the broadest types of shame relevant to OCRDs; symptom-based shame and body shame may be more specific to OCRDs. In OCD, violent, sexual, or blasphemous obsessions may trigger symptom-based shame. In trichotillomania (TTM) and skin picking (SP), symptom-based shame may be related to pulling, picking, and post-pulling/picking behaviors. In hoarding disorder, symptom-based shame may accompany beliefs about being defective due to living with clutter. Body shame appears inherent to body dysmorphic disorder, while in TTM and SP it may arise as a secondary response to damage resulting from body focused repetitive behaviors.

LIMITATIONS

Much of the current knowledge on shame in OCRDs comes from anecdotal, case, and conceptual work. Empirical studies do not always assess specific types of shame, instead assessing shame as a general construct.

CONCLUSIONS

Shame is closely related to OCRDs. Clinical and research recommendations drawing from the literature are provided.