Introduction and conceptualization Hair-pulling disorder (HPD) has not received much attention in comparison to other psychiatric illnesses. Considering South African research, only a limited number of studies have focused on HPD with minimal focus on treatment interventions. Several treatments with regards to pharmacotherapy and psychotherapy have been developed and investigated. Evidence suggests limited efficacy of these treatments, thus there is a need for an intervention that shows better efficacy in symptom reduction with longer maintenance of treatment gains, whilst also being cost-effective and easily accessible. Studies have indicated that patients with HPD experience difficulty in working memory (WM), impulse control (IC) and emotion regulation (ER). The involvement of the frontoparietal circuitry, as well as frontal cortex, amygdalo-hippocampal formation and putamen have been specified in HPD. WM and ER circuitry are both based in the frontoparietal neural circuit, and thus training of WM shows potential to also address ER difficulties. An intervention focusing on WM training, may promise to address difficulties in IC and ER, and thus be appropriate in the treatment of patients with HPD. Cognitive training (CT) is a novel intervention that focuses on enhancing executive functioning and more specifically WM. WM tasks in CT also focus on the frontoparietal network which plays a role in ER, and therefore when this network is activated by executive functioning tasks, ER should improve. The positive impact of computerized cognitive training (CCT) on neuroplasticity in these indicated pathways have recently been acknowledged. Psychotherapeutic support might not be readily available or accessible to most people in developing countries, such as South Africa. Indeed, locally the physical distance from mental health centres and cost of individual sessions with health care professionals, are challenging - preventing patients finding the help that they need. CT can thus be a more accessible and cost-effective alternative. Cogmed Working Memory Training, an internet-based CT program, will be investigated for its efficacy in the treatment of HPD.

Purpose of the study: The principal aim of this project is to establish the impact of CT in patients with primary HPD. Study findings will also provide information on whether an internet based CT intervention, done at patients' homes, is feasible as a mode of treatment for HPD patients in SA. The proposed research will focus on the following objectives: To determine the effect of CT (25 sessions over 5 weeks) on WM, ER, IC and hair-pulling severity (HPS), in patients with HPD. To determine whether the effect of the true CT program on WM, ER, IC and HPS differed from that of the active control program. To determine whether effects are maintained at 3 months post-intervention. To qualitatively explore participants' subjective experience of the intervention process and responses to CT (in terms of WM, ER, IC and HPS).

It is hypothesised that after 5 weeks of CT, the treatment HPD group will show significant improvement in WM, ER, IC and significant reduction in HPS. The effect of the true CT program on WM, ER, IC and HPS will be significantly different from the active control group. During a 3-month follow-up evaluation, the HPD intervention group will have maintained reduction in symptoms after the treatment, compared to the active control HPD group. The treatment HPD group will generally be positive about the effects of CT on HPD and their functioning at post-intervention and 3-month follow-up and consider CT as easy to use and affordable.

Study design: The study design is a 5-week, 25-session intervention study with an active control, and 3-month follow-up evaluation. As a registered clinical psychologist, the principal investigator has the expertise to diagnose, do clinical interviews, and implement the psychometric battery pre and post intervention. Inclusion criteria is a primary diagnosis of HPD (DSM-5); Adults (18 years and older); Fluent in English; Access to the internet for the duration of their study participation. Exclusion criteria is any significant current DSM comorbidity; Montgomery-Asberg Depression Rating Scale (MADRS) Score \> 20 to exclude patients with comorbid depressive syndromes; Previous exposure to cognitive training (previous 'brain training' games on cell phone and/or computer allowed). The criteria will be assessed during the screening procedure. Participants will enter the study as recruited and randomly assigned to the treatment or active control group. Participants entering the study will be randomized into the intervention or active control group, using a randomization list provided by the statistician. The intervention task (Cogmed QM) and the placebo (Jigsaw Puzzles) differ significantly. The principal investigator will not be blind to the group that the participants are in, whereas the participants will be blind to their group inclusion. It is aimed to achieve a sample size of at least 40 (20 treatment, 20 active control). This is comparable to group sizes in other HPD treatment studies. The research method is based in embedded theory design, utilizing both quantitative and qualitative components. The benefit of this hybrid approach is to be able to investigate and describe subject matter with statistical power, as well as being able to comment on the participant's experience, thus creating a richer and more holistic description of the research theme. The quantitative research consists of the pre- and post intervention assessment battery, 3-month follow-up evaluation and continuous information provided by the treatment intervention (Cogmed). The qualitative data analysis will be done on semi-structured interviews, as part of the pre- and post assessment battery and 3-month follow-up evaluation. Pre- and post intervention data collection will be done by the principal investigator by means of the assessment battery including both quantitative and qualitative measures. Statistical analysis will be conducted using mixed model repeated measures ANOVA, which is most suitable for dealing with possible lost to follow-up. Patients in the study will be treated as random effects (randomly selected from a larger population). Treatment (intervention vs placebo) and time (pre, post, 3 months) will be treated as fixed effects. The treatment\*time interaction effect will be the primary effect of investigation because it tests whether the change over time is the same for the two groups. If the intervention has a different effect to the placebo, then this interaction effect should be significant. Post hoc testing will be done using Fisher Least Significant Difference (LSD) testing. Normality assumptions will be checked for all analyses and appropriately dealt with if necessary, based on the nature of the data. A 5% significance level will be used as guideline for significant results. The qualitative data will be analysed using an interpretative phenomenological approach (TerreBlanche, Durrheim, \& Kelly, 2010), utilizing a qualitative data analysis software program, Atlas.ti.

Anticipated benefits and risks: CT has not been investigated as a treatment intervention for HPD and reduction of HPS cannot be guaranteed. However, HPS may reduce during the true CT program. Participants, who are part of the placebo group, will get the opportunity to access the true CT program on completion of the study. Except for the fact that they might not be in the treatment group for the duration of the study due to randomization, there are no known risks involved in participation.

Ethical Considerations: The study procedures, risks and benefits will be communicated in lay terminology to all participants (verbally and in writing) in Afrikaans or English. All data collected will be kept strictly confidential and study results made public and published without compromising confidentiality. The demographics questionnaire will be removed from the questionnaire pack to ensure that the completed questionnaires and the demographic details cannot be linked. Personal identifying details such as the name and contact information will not be recorded on the electronic database. All participants will be allocated a unique study code on the electronic database. Identifiers linked to a study code will be kept in a separate, password protected file. Only the principal investigator will have access to this information. It will be clearly indicated that the participant is free to withdraw participation from this trial, without consequence. Participating individuals will incur no costs.