How Does Cognition Differ in People with Trichotillomania?

What you need to know

• People with trichotillomania show impairments in motor inhibition and cognitive flexibility compared to healthy individuals.
• Other cognitive abilities like memory, planning, and verbal skills appear to be unaffected in trichotillomania.
• These findings suggest trichotillomania involves specific cognitive deficits rather than broad impairments across multiple domains.

Understanding Trichotillomania

Trichotillomania, also known as hair-pulling disorder, is a mental health condition characterized by recurrent urges to pull out one’s own hair. This can result in noticeable hair loss and significant distress or impairment in daily life. Trichotillomania affects about 1-2% of the population and typically begins in adolescence.

To better understand the cognitive processes involved in trichotillomania, researchers have conducted various studies comparing cognitive performance between people with trichotillomania and healthy individuals without the condition. However, results from individual studies have been inconsistent. This meta-analysis aimed to synthesize findings across multiple studies to identify robust patterns in cognitive functioning associated with trichotillomania.

Specific Cognitive Deficits in Trichotillomania

The meta-analysis revealed two key areas where people with trichotillomania showed impaired performance compared to healthy controls:

Impaired Motor Inhibition

Motor inhibition refers to the ability to stop or suppress a physical action. This was measured using a task called the stop-signal task. In this task, participants are asked to respond quickly to a stimulus, but occasionally they are given a “stop signal” indicating they should withhold their response.

People with trichotillomania showed significantly slower stop-signal reaction times compared to healthy controls. This suggests they have more difficulty inhibiting or stopping an action once it has been initiated. The impairment in motor inhibition had a medium effect size, indicating a notable difference between groups.

This finding aligns with the core symptoms of trichotillomania - difficulty resisting the urge to pull hair despite wanting to stop. Impaired motor inhibition may contribute to challenges in controlling the hair-pulling behavior.

Impaired Cognitive Flexibility

Cognitive flexibility refers to the ability to adapt thinking and behavior in response to changing situations or rules. This was assessed using a task called the extradimensional (ED) set-shifting task. In this task, participants learn to respond to stimuli based on one feature (e.g. shape) and then must switch to responding based on a different feature (e.g. color).

The analysis found that people with trichotillomania performed significantly worse on the ED set-shifting portion of the task compared to healthy controls. This suggests they have more difficulty shifting their attention and adapting their responses when rules change.

Impaired cognitive flexibility may help explain the repetitive nature of hair-pulling behaviors in trichotillomania. People may have trouble disengaging from the behavior or shifting to alternative coping strategies.

Unaffected Cognitive Abilities

Importantly, the meta-analysis found no significant differences between people with trichotillomania and healthy controls in several other cognitive domains:

• Verbal learning and memory
• Visual memory
• Visuospatial abilities
• Executive planning
• Attention

This suggests that trichotillomania is associated with specific deficits in motor inhibition and cognitive flexibility rather than broad cognitive impairment across multiple domains.

Implications for Understanding Trichotillomania

These findings provide important insights into the cognitive processes involved in trichotillomania:

Distinct from OCD

Trichotillomania is classified as an obsessive-compulsive related disorder. However, the specific pattern of cognitive deficits differs from what is typically seen in obsessive-compulsive disorder (OCD). People with OCD often show impairments across a wider range of cognitive domains.

The more limited cognitive deficits in trichotillomania suggest it may have distinct underlying neurobiological mechanisms compared to OCD, despite some phenomenological similarities.

Potential Treatment Targets

Identifying specific cognitive impairments provides potential targets for treatment interventions. Cognitive remediation approaches aimed at improving motor inhibition and cognitive flexibility may be beneficial as adjuncts to standard treatments for trichotillomania.

Additionally, cognitive testing could potentially be used to identify individuals at higher risk for trichotillomania or to track treatment progress.

Developmental Considerations

Some studies included in the analysis found differences in cognitive performance between children and adults with trichotillomania. This raises the possibility that cognitive deficits may manifest differently across development.

More research is needed to clarify how cognitive functioning in trichotillomania may change from childhood to adulthood. This could inform early intervention approaches.

Limitations and Future Directions

While this meta-analysis provides valuable insights, there are some important limitations to consider:

• Many of the included studies had relatively small sample sizes
• There was limited diversity in terms of ethnicity and gender in the samples
• Some cognitive domains only had data from a small number of studies

Future research should aim to:

• Conduct larger studies with more diverse samples
• Compare cognitive functioning between potential subtypes of trichotillomania (e.g. “focused” vs “automatic” pulling)
• Investigate how cognitive deficits relate to symptom severity and treatment outcomes
• Use neuroimaging to examine the neural basis of the observed cognitive impairments

Conclusions

• People with trichotillomania show impairments in motor inhibition and cognitive flexibility compared to healthy individuals.
• Other cognitive abilities appear to be intact in trichotillomania.
• These specific deficits may contribute to difficulties controlling hair-pulling urges and behaviors.
• Targeting motor inhibition and cognitive flexibility could be promising for developing new treatment approaches.