Systematic Review of Published Primary Studies of Neuropsychology and Neuroimaging in Trichotillomania

Neurocognitive functioning in adults with trichotillomania: Predictors of treatment response and symptom severity in a randomized control trial

Trichotillomania (TTM) is associated with impairments in response inhibition and cognitive flexibility, but it is unclear how such impairments relate to treatment outcome. The present study examined pre-treatment response inhibition and cognitive flexibility as predictors of treatment outcome, change in these domains from pre-to post-treatment, and associations with TTM severity. Participants were drawn from a randomized controlled trial comparing acceptance-enhanced behavior therapy (AEBT) to psychoeducation and supportive therapy (PST) for TTM. Adults completed assessments at pre-treatment (n = 88) and following 12 weeks of treatment (n = 68). Response inhibition and cognitive flexibility were assessed using the Stop Signal Task and Object Alternation Task, respectively. Participants completed the MGH-Hairpulling Scale. Independent evaluators administered the NIMH-Trichotillomania Severity Scale and Clinical Global Impressions-Improvement Scale. Higher pre-treatment TTM severity was associated with poorer pre-treatment cognitive flexibility, but not response inhibition. Better pre-treatment response inhibition performance predicted positive treatment response and lower post-treatment TTM symptom severity, irrespective of treatment assignment. Cognitive flexibility did not predict treatment response. After controlling for age, neither neurocognitive variable changed during treatment. Response inhibition and cognitive flexibility appear uniquely related to hair pulling severity and treatment response in adults with TTM. Implications for treatment delivery and development are discussed.

Cognition in trichotillomania: a meta-analysis

OBJECTIVE

Trichotillomania (TTM) is a mental health disorder characterized by repetitive urges to pull out one's hair. Cognitive deficits have been reported in people with TTM compared to controls; however, the current literature is sparse and inconclusive about affected domains. We aimed to synthesize research on cognitive functioning in TTM and investigate which cognitive domains are impaired.

METHODS

After preregistration on the International Prospective Register of Systematic Reviews (PROSPERO), we conducted a comprehensive literature search for papers examining cognition in people with TTM versus controls using validated tests. A total of 793 papers were screened using preestablished inclusion/exclusion criteria, yielding 15 eligible studies. Random-effects meta-analysis was conducted for 12 cognitive domains.

RESULTS

Meta-analysis demonstrated significant deficits in motor inhibition and extradimensional (ED) shifting in people with TTM versus controls as measured by the stop-signal task (SST) (Hedge's g = 0.45, [CI: 0.14, 0.75], p = .004) and ED set-shift task (g = 0.38, [CI: 0.13, 0.62], p = .003), respectively. There were no significant between-group differences in the other cognitive domains tested: verbal learning, intradimensional (ID) shifting, road map spatial ability, pattern recognition, nonverbal memory, executive planning, spatial span length, Stroop inhibition, Wisconsin card sorting, and visuospatial functioning. Findings were not significantly moderated by study quality scores.

CONCLUSIONS

Motor inhibition and ED set-shifting appear impaired in TTM. However, a cautious interpretation of results is necessary as samples were relatively small and frequently included comorbidities. Treatment interventions seeking to improve inhibitory control and cognitive flexibility merit exploration for TTM.

Impulsivity in adolescent girls diagnosed with trichotillomania: an evaluation of clinical and neuropsychological characteristics

The aim of this study is to compare the clinical and neuropsychological features of impulsivity in adolescent girls with trichotillomania (TTM) and healthy controls, and to assess the relationships between the severity of TTM and the impulsivity/concomitant symptoms of anxiety and depression. The study sample consisted of 43 adolescent girls who were 12 to 18 years old. The Kiddie-Schedule for Affective Disorders and Schizophrenia for School Age Children-Present and Lifetime Version DSM-5 (K-SADS-PL) was administered to the adolescents and their parents. All of the participants completed a sociodemographic data form, the Revised Children's Anxiety and Depression Scale-Child Version (RCADS-CV), the Barratt Impulsiveness Scale-Brief (BIS-Brief), and the Massachusetts General Hospital Hairpulling Scale (MGH-HPS). The Eriksen Flanker task, the Stop Signal Reaction Time (SSRT) task, the Go/No-Go task, and the Balloon Analog Risk Task (BART) were used to assess behavioral impulsivity. The adolescents with TTM reported higher levels of impulsivity and anxiety/depression symptoms than the healthy controls, and they also performed worse on the behavioral tasks. While there were no relationships between clinical and behavioral impulsivity and TTM severity, social anxiety symptoms were the most important predictor of the severity of TTM. It seems important to better understand the role of impulsivity in the onset and persistence of TTM symptoms in adolescents.

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.

Body-focused repetitive behaviors: Beyond bad habits

ABSTRACT

Body-focused repetitive behavior (BFRB) is a significantly underrecognized phenomenon that can cause physical complications and marked mental distress. Understanding the condition and offering patients pharmacologic as well as psychotherapeutic support may effectively reduce adverse health outcomes. This article reviews BFRBs, which can present clinically in multiple settings.

Duration of illness and cortical thickness in trichotillomania: Preliminary evidence for illness change over time

Trichotillomania is a psychiatric condition characterized by repetitive pulling out of one's hair, leading to marked functional impairment. The aim of this study was to examine the association between duration of trichotillomania (defined as time between initial age of onset and current age) and structural brain abnormalities by pooling all available global data. Authors of published neuroimaging studies of trichotillomania were contacted and invited to contribute de-identified MRI scans for a pooled analysis. Freesurfer pipelines were used to examine whether cortical thickness and sub-cortical volumes were associated with duration of illness in adults with trichotillomania. The sample comprised 50 adults with trichotillomania (100% not taking psychotropic medication; mean [SD] age 34.3 [12.3] years; 92% female). Longer duration of illness was associated with lower cortical thickness in bilateral superior frontal cortex and left rostral middle frontal cortex. Volumes of the a priori sub-cortical structures of interest were not significantly correlated with duration of illness (all p > 0.05 uncorrected). This study is the first to suggest that trichotillomania is associated with biological changes over time. If this finding is supported by prospective studies, it could have important implications for treatment (i.e. treatment might need to be tailored for stage of illness). Viewed alongside prior work, the data suggest that brain changes in trichotillomania may be differentially associated with vulnerability (excess thickness in right inferior frontal cortex) and with chronicity (reduced thickness in medial and superior frontal cortex). Longitudinal research is now indicated.