Dronabinol, a cannabinoid agonist, reduces hair pulling in trichotillomania: a pilot study

Cannabinoids in the Treatment of Selected Mental Illnesses: Practical Approach and Overview of the Literature

Although an increasing number of patients suffering from mental illnesses self-medicate with cannabis, current knowledge about the efficacy and safety of cannabis-based medicine in psychiatry is still extremely limited. So far, no cannabis-based finished product has been approved for the treatment of a mental illness. There is increasing evidence that cannabinoids may improve symptoms in autism spectrum disorder (ASD), Tourette syndrome (TS), anxiety disorders, and post-traumatic stress disorder (PTSD). According to surveys, patients often use cannabinoids to improve mood, sleep, and symptoms of attention deficit/hyperactivity disorder (ADHD). There is evidence suggesting that tetrahydrocannabinol (THC) and THC-containing cannabis extracts, such as nabiximols, can be used as substitutes in patients with cannabis use disorder.Preliminary evidence also suggests an involvement of the endocannabinoid system (ECS) in the pathophysiology of TS, ADHD, and PTSD. Since the ECS is the most important neuromodulatory system in the brain, it possibly induces beneficial effects of cannabinoids by alterations in other neurotransmitter systems. Finally, the ECS is an important stress management system. Thus, cannabinoids may improve symptoms in patients with mental illnesses by reducing stress.Practically, cannabis-based treatment in patients with psychiatric disorders does not differ from other indications. The starting dose of THC-containing products should be low (1-2.5 mg THC/day), and the dose should be up-titrated slowly (by 1-2.5 mg every 3-5 days). The average daily dose is 10-20 mg THC. In contrast, cannabidiol (CBD) is mainly used in high doses>400 mg/day.

Cannabinoids for the Treatment of Dermatologic Conditions

In recent years, cannabinoid (CB) products have gained popularity among the public. The anti-inflammatory properties of CBs have piqued the interest of researchers and clinicians because they represent promising avenues for the treatment of autoimmune and inflammatory skin disorders that may be refractory to conventional therapy. The objective of this study was to review the existing literature regarding CBs for dermatologic conditions. A primary literature search was conducted in October 2020, using the PubMed and Embase databases, for all articles published from 1965 to October 2020. Review articles, studies using animal models, and nondermatologic and pharmacologic studies were excluded. From 248 nonduplicated studies, 26 articles were included. There were 13 articles on systemic CBs and 14 reports on topical CBs. Selective CB receptor type 2 agonists were found to be effective in treating diffuse cutaneous systemic sclerosis and dermatomyositis. Dronabinol showed efficacy for trichotillomania. Sublingual cannabidiol and Δ-9-tetrahydrocannabinol were successful in treating the pain associated with epidermolysis bullosa. Available evidence suggests that CBs may be effective for the treatment of various inflammatory skin disorders. Although promising, additional research is necessary to evaluate efficacy and to determine dosing, safety, and long-term treatment guidelines.

Medical Cannabis and Psychiatric Disorders: Implications for Psychiatric Nurses

OBJECTIVE

Cannabis use for medical condition has significantly increased over the past 20 years with 33 states and the District of Columbia passing laws legalizing medical cannabis. Five qualifying psychiatric disorders have been identified. The objective of this review article is to present a brief history of medical cannabis, the evidence for the qualifying psychiatric conditions, and to discuss the implications for psychiatric nurses.

METHOD

A review of the literature on the five qualifying psychiatric disorders was conducted. Databases searched included CINAHL, PubMed, Cochrane Library, MedLine Plus, and EMBASE. Keywords were cannabis, medical cannabis, delta-9-tetrahydrocannabinaol, cannabidiol, and psychiatric disorders.

RESULTS

The evidence that medical cannabis or cannabinoids is an effective treatment for the qualifying psychiatric disorders (e.g., posttraumatic stress disorder, agitation in Alzheimer's disease and other dementias, Tourette's syndrome, anxiety, and obsessive-compulsive disorder) is too weak and of low quality to recommend as an intervention at this time. A discussion of the implications of these findings for psychiatric nurses is offered based on the published guidelines by the American Nurses Association and National Council of State Boards of Nursing.

CONCLUSION

There is a significant gap between evidence supporting the effectiveness of medical cannabis for psychiatric disorders and patient interest and use of cannabis for such conditions as well as other psychiatric symptoms. There are tremendous opportunities for psychiatric nurses to make an impact both clinically and be conducting research in this emerging field. We need to educate ourselves and our patients about the benefits and risks of medical cannabis and to help patients make informed decisions about their health care.

Tetrahydrocannabinol fails to reduce hair pulling or skin picking: results of a double-blind, placebo-controlled study of dronabinol

Body-focused repetitive behaviors (BFRBs) such as trichotillomania and skin picking disorder are associated with decreased self-esteem and poor quality of life. The objective of this study was to evaluate dronabinol, a cannabinoid agonist, for the reduction of BFRB symptoms. Fifty adults with either trichotillomania (n = 34) or skin picking disorder (n = 16) were recruited for a randomized, double-blind, placebo-controlled study. Participants received 10-week treatment with dronabinol (5-15 mg/day) or placebo. The primary efficacy outcome measure was the change on the clinician-rated National Institute of Mental Health scale for hair pulling or skin picking. Both dronabinol and placebo treatment were associated with significant reductions in BFRB symptoms. Dronabinol did not significantly separate from placebo on any efficacy measure. At week 10, 67% of the treatment group were classified as responders (Clinical Global Impressions-Improvement Score of very much or much improved) compared to 50% in the placebo group (P value = 0.459). This study assessed the efficacy of dronabinol, a synthetic form of tetrahydrocannabinol, in the treatment of BFRBs, and found no differences in symptom reductions between dronabinol and placebo.

Psychological Aspects of Hair Disorders: Consideration for Dermatologists, Cosmetologists, Aesthetic, and Plastic Surgeons

Hair loss disorders may cause considerable distress to patients. Although many do not pose a significant medical risk, the sociocultural importance of hair is substantial. Often the extent of hair loss does not correlate to the impact on psychosocial function, thus necessitating an individualized approach. Hair loss disorders are interrelated with mental health and at times exert significant psychological percussions, and therefore, providers should address both medical and psychological aspects of treatment. This review contains a discussion of the impact on quality of life of common hair loss disorders and the psychological approaches that providers may utilize to improve care. The incorporation of psychodermatology and psychotrichology in dermatology and psychiatry residency programs is of vital importance. Dermatology and psychiatry liaison clinics may prove useful in the treatment of these patients.

Trichotillomania and Skin-Picking Disorder: An Update

Trichotillomania (hair pulling disorder) and skin-picking (excoriation) disorder are common neuropsychiatric disorders (each with a point prevalence of around 2%) but are underrecognized by professionals. Affected individuals repeatedly pull out their own hair or pick at their skin, and these symptoms not only have a negative impact on these individuals because of the time they occupy but can also lead to considerable physical disfigurement, with concomitant loss of self-esteem and avoidance of social activities and intimate relationships. The behaviors may also have serious physical consequences. Trichotillomania and skin picking frequently co-occur, and both disorders commonly present with co-occurring depression, anxiety, impulsive, and obsessive-compulsive disorders. Behavioral therapy currently appears to be the most effective treatment for both. Pharmacotherapy, in the form of N-acetylcysteine or olanzapine, may also play a role in treatment.

Pharmacotherapy for trichotillomania

BACKGROUND

Trichotillomania (TTM; hair-pulling disorder) is a prevalent and disabling disorder characterised by recurrent hair-pulling. Here we update a previous Cochrane Review on the effects of medication for TTM.

OBJECTIVES

To assess the effects of medication for trichotillomania (TTM) in adults, children and adolescents compared with placebo or other medication.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, PsycINFO, eleven other bibliographic databases, trial registries and grey literature sources (to 26 November 2020). We checked reference lists and contacted subject experts.

SELECTION CRITERIA

We selected randomised controlled trials of medication versus placebo or other medication for TTM in adults, children and adolescents.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

Twelve studies were included. We identified 10 studies in adults (286 participants) with a mean sample size of 29 participants per trial; one study in children and adolescents (39 participants); and, one study in adults and adolescents (22 participants: 18 adults and 4 adolescents). All studies were single-centre, outpatient trials. Eleven studies compared medication and placebo (334 participants); one study compared two medications (13 participants). Studies were 5 to 13 weeks duration. We undertook meta-analysis only for opioid antagonists as other comparisons contained a single study, or reported insufficient data. Antioxidants versus placebo in adults There was little to no difference in treatment response between antioxidant (35.7%) and placebo groups (28.6%) after six weeks, based on a single trial of silymarin (risk ratio (RR) 2.25, 95% confidence interval (CI) 0.84 to 5.99; 36 participants; low-certainty evidence). We could not calculate differences in number of dropouts as there were no events in either group (18 participants; low-certainty evidence). Antioxidants versus placebo in adolescents There was little to no difference in treatment response between antioxidant (50%) and placebo groups (25%) after six weeks, based on a single trial of silymarin (RR 2.00, 95% CI 0.28 to 14.20; 8 participants; low-certainty evidence). We could not calculate differences in number of dropouts as there were no events in either group (8 participants; low-certainty evidence). Antipsychotics versus placebo in adults There may be greater treatment response in the antipsychotic group (85%) compared to the placebo group (17%) after 12 weeks, based on a single trial of olanzapine (RR 5.08, 95% CI 1.4 to 18.37; 25 participants; low-certainty evidence). We could not calculate differences in number of dropouts as there were no events in either group (25 participants; low-certainty evidence). Cell signal transducers versus placebo in adults There was little to no difference in treatment response between cell signal transducer (42.1%) and placebo groups (31.6%) after 10 weeks, based on a single trial of inositol (RR 1.33, 95% CI 0.57 to 3.11; 38 participants; low-certainty evidence). We could not calculate differences in number of dropouts as there were no events in either group (38 participants; low-certainty evidence). Glutamate modulators versus placebo in adults There is probably greater treatment response in the glutamate modulator group (56%) compared to the placebo group (16%) after 12 weeks, based on a single trial of N-acetylcysteine (RR 3.5, 95% CI 1.34 to 9.17; 50 participants; moderate-certainty evidence). We could not calculate differences in number of dropouts as there were no events in either group (50 participants; low-certainty evidence). Glutamate modulators versus placebo in children and adolescents There was little to no difference in treatment response between the glutamate modulator (25%) and placebo groups (21.1%) in children and adolescents, based on a single trial of N-acetylcysteine (RR 1.19, 95% CI 0.37 to 3.77; 39 participants; low-certainty evidence). There was little to no difference in dropouts due to adverse events between glutamate modulator (5%) and placebo (0%) groups, based on a single trial (RR 2.86, 95% CI 0.12 to 66.11; 39 participants; low-certainty evidence). Opioid antagonists versus placebo in adults There may be little to no difference in treatment response between opioid antagonist (37.5%) and placebo groups (25%) after six to eight weeks, based on two studies of naltrexone, but the evidence is very uncertain (RR 2.14, 95% CI 0.25 to 18.17; 2 studies, 68 participants; very low-certainty evidence). No data were available regarding dropouts due to adverse events. Selective serotonin reuptake inhibitors (SSRIs) versus placebo in adults There were no data available for treatment response to SSRIs. There was little to no difference in dropouts due to adverse events in the SSRI group (5.1%) compared to the placebo group (0%) after 6 to 12 weeks, based on two trials of fluoxetine (RR 3.00, 95% CI 0.33 to 27.62; 2 studies, 78 participants; low-certainty evidence). Tricyclic antidepressants (TCAs) with predominantly serotonin reuptake inhibitor (SRI) actions versus placebo in adults There may be greater treatment response in the TCAs with predominantly SRI actions group (40%) compared to the placebo group (0%) after nine weeks, but the evidence is very uncertain, based on a single trial of clomipramine (RR 5.73, 95% CI 0.36 to 90.83; 16 participants; very low-certainty evidence). There may be increased dropouts due to adverse events in the TCAs with predominantly SRI actions group (30%) compared to the placebo group (0%), but the evidence is very uncertain (RR 4.45, 95% CI 0.27 to 73.81; 16 participants; very low-certainty evidence). TCAs with predominantly SRI actions versus other TCAs in adults There may be greater treatment response in the TCAs with predominantly SRI actions group compared to the other TCAs group after five weeks, based on a single trial comparing clomipramine to desipramine (mean difference (MD) -4.00, 95% CI -6.13 to -1.87; 26 participants; low-certainty evidence). We could not calculate differences in number of dropouts as there were no events in either group (26 participants; low-certainty evidence).

AUTHORS' CONCLUSIONS

There was insufficient evidence from meta-analysis to confirm or refute the efficacy of any agent or class of medication for the treatment of TTM in adults, children or adolescents. Preliminary evidence suggests there may be beneficial treatment effects for N-acetylcysteine, clomipramine and olanzapine in adults based on four trials, albeit with relatively small sample sizes.

Cannabinoid use and self-injurious behaviours: A systematic review and meta-analysis

BACKGROUND

The increasing availability of high-potency cannabis-derived compounds and the use of synthetic cannabinoids may be responsible for severe side effects like cognitive impairment, psychosis or self-injurious behaviours (SIB). In particular, SIB like non-suicidal self-injury (NSSI) and deliberate self-harm (DSH) raise growing concern as a possible consequence of cannabis use. However, the research to date has not addressed the relationship between cannabinoid use and SIB systematically.

METHODS

We conducted a systematic review on PubMed up to March 2020, using search terms related to cannabinoids and SIB.

RESULTS

The search yielded a total of 440 abstracts. Of those, 37 studies published between 1995 and 2020 were eligible for inclusion. Cannabinoid use was significantly associated with SIB at the cross-sectional (OR=1.569, 95%CI [1.167-2.108]) and longitudinal (OR=2.569, 95%CI [2.207-3.256]) level. Chronic use, presence of mental disorders, depressive symptoms, emotional dysregulation and impulsive traits might further increase the likelihood of self-harm in cannabis users. Synthetic cannabinoids may trigger highly destructive SIB mainly through the psychotomimetic properties of these compounds.

CONCLUSION

Cannabinoid use was associated with an increased prevalence of self-injury and may act as a causative factor with a duration-dependent manner. Emotional regulation and behavioural impulsivity functions might crucially moderate this association. Future studies should further investigate the mechanisms underlying this association, while exploring potential therapeutic applications of substances modulating the endocannabinoid system.

Pharmacotherapy for trichotillomania in adults

INTRODUCTION

Currently conceptualized as an obsessive compulsive and related disorder, trichotillomania, or hair-pulling disorder, is a common illness that causes significant distress or functional impairments in various life domains. Most individuals with trichotillomania also have other comorbid diagnoses. Treating trichotillomania with pharmacotherapy is complicated since there are currently no FDA-approved drugs for its treatment.

AREAS COVERED

The databases PubMed, PsychINFO, CINAHL, Evidence-based Medicine Reviews, and Cochrane Database of Systematic Reviews were searched, yielding a total of 10 open trials and 10 controlled trials selected. This review aims to examine pharmacotherapeutic options for the treatment of trichotillomania in adults and makes recommendations for the assessment and management of the disorder.

EXPERT OPINION

There is preliminary evidence that clomipramine, olanzapine, and N-acetylcysteine may be effective in cases of trichotillomania, however, given the paucity of controlled studies with large sample sizes, decisions regarding the use of drugs should be made on a case-by-case basis taking into account the severity of trichotillomania and the nature of psychiatric comorbidity.

Recent advances in the treatment of trichotillomania (hair-pulling disorder)

Trichotillomania (TTM) is a condition in which affected individuals pull out their hair resulting in hair loss. This disorder affects roughly 0.5% to 2.0% of the population and can have significant psychological morbidity. Behavioral therapy has been used with success in the treatment of TTM, but not all patients are willing or able to comply with this treatment strategy. There is a need for effective pharmacological treatment options. Historically, pharmacotherapy for TTM has been inadequate in most cases, but recent advances have been made in this regard. Fluoxetine, clomipramine, olanzapine, and naltrexone have all been used in the treatment of TTM, but evidence of benefit has varied, and side effect profiles can limit practical utility. Recent advances in the understanding of the pathophysiology of TTM, as well as evidence of benefit seen with some glutamate-modulating agents such as N-acetylcysteine and dronabinol, have provided newer potential pharmacotherapy options.

The Endocannabinoid System: A New Treatment Target for Obsessive Compulsive Disorder?

Introduction: Obsessive-compulsive disorder (OCD) is a disabling illness that is associated with significant functional impairment. Although evidence-based pharmacotherapies exist, currently available medications are ineffective in some patients and may cause intolerable side effects in others. There is an urgent need for new treatments. Discussion: A growing body of basic and clinical research has showed that the endocannabinoid system (ECS) plays a role in anxiety, fear, and repetitive behaviors. At the same time, some patients with OCD who smoke cannabis anecdotally report that it relieves their symptoms and mitigates anxiety, and several case reports describe patients whose OCD symptoms improved after they were treated with cannabinoids. Taken together, these findings suggest that the ECS could be a potential target for novel medications for OCD. In this study, we review evidence from both animal and human studies that suggests that the ECS may play a role in OCD and related disorders. We also describe findings from studies in which cannabinoid drugs were shown to impact symptoms of these conditions. Conclusions: An emerging body of evidence suggests that the ECS plays a role in OCD symptoms and may be a target for the development of novel medications. Further exploration of this topic through well-designed human trials is warranted.

Trichotillomania and Trichophagia: Modern Diagnostic and Therapeutic Methods

Trichotillomania is a chronic, mental disease of impulse control, characterized by repetitive, compulsive, and self-induced hair pulling. It can occur at any age but is observed more often in adolescents, with a strong predominance in females. Diagnosis of trichotillomania may be difficult, and its effective treatment challenging. The aim of this study is to critically review current literature regarding diagnostic procedures and treatment of trichotillomania, including psychotherapy, N-acetylcysteine, naltrexone, topiramate, atypical neuroleptics, and selective serotonin-reuptake inhibitors. The importance of cooperation between dermatologists and psychiatrists is emphasized to shorten the time to diagnose the disease and begin appropriate treatment. Finally, trichotillomania is also often connected with trichophagia, which may lead to formation of trichobezoars and cause a direct danger to the patient’s health and even life due to the risk of intestinal obstruction and the need for surgical intervention. Based on thorough literature review, we conclude that diagnosis of trichotillomania can be challenging. Trichoscopy could help to distinguish trichotillomania from other types of hair loss. Most clinical trials using various treatment options have been conducted on small groups of patients, and the potential benefits determined using various scales. Therefore, it is difficult to compare the effectiveness of different treatment methods. There is also a lack of studies assessing treatment efficacy over longer periods of time. Thus, there is a need to perform better-designed studies in the near future to optimize current treatment modalities for trichotillomania.

“Pulling hair out of the head” - the importance of traumatic family events in the development and maintenance of trichotillomania symptoms - case report

Introduction: Trichotillomania is a mental disorder characterized by a repetitive and compulsive hair pulling, classified in ICD-10 to a group of habit and impulse disorders, and in the DSM-5 to the group of obsessive-compulsive disorders.

Aim: The aim of the study is to present on the basis of case study:1). the importance of traumatic family experiences in releasing as well as maintaining the symptoms of Trichotillomania, 2). comprehensive medical care, the application of which has resulted in a beneficial therapeutic effect.

Results: In the described case of 16-year-old patient, Trichotillomania was triggered by traumatic events related to lack of support and family stabilization resulting from parental disputes and grandfather’s death, when she was 11 years old. The subsequent years of her life, in spite of the divorce of her parents and their separate residence, abounded in periods of turbulent quarrels between the parents in which she was involved. Each time this type of incident was associated with the recurrence of behavior associated with Trichotil-lomania, the course of which was more severe with the occurrence of self-harm and suicidal thoughts.

Conclusions: 1. In the described case, traumatic events and pathological relations of the immediate family members were not only thetriggering factor, but also maintaining the Trichotillomania symptoms. 2. In accordance with the guidelines of Trichotillomania Learning Center-Scientific Advisory Board (2008), the use of a comprehensive treatment including both the patient - individual psycho-therapy (especially cognitive-behavioral therapy) and pharmacotherapy, as well as her family (family psychotherapy, family mediation, workshops for parents), brought about positive therapeutic effects.

Is cannabis treatment for anxiety, mood, and related disorders ready for prime time?

Anxiety and related disorders are the most common mental conditions affecting the North American population. Despite their established efficacy, first-line antidepressant treatments are associated with significant side effects, leading many afflicted individuals to seek alternative treatments. Cannabis is commonly viewed as a natural alternative for a variety of medical and mental health conditions. Currently, anxiety ranks among the top five medical symptoms for which North Americans report using medical marijuana. However, upon careful review of the extant treatment literature, the anxiolytic effects of cannabis in clinical populations are surprisingly not well-documented. The effects of cannabis on anxiety and mood symptoms have been examined in healthy populations and in several small studies of synthetic cannabinoid agents but there are currently no studies which have examined the effects of the cannabis plant on anxiety and related disorders. In light of the rapidly shifting landscape regarding the legalization of cannabis for medical and recreational purposes, it is important to highlight the significant disconnect between the scientific literature, public opinion, and related policies. The aim of this article is to provide a comprehensive review of the current cannabis treatment literature, and to identify the potential for cannabis to be used as a therapeutic intervention for anxiety, mood, and related disorders. Searches of five electronic databases were conducted (PubMed, MEDLINE, Web of Science, PsychINFO, and Google Scholar), with the most recent in February 2017. The effects of cannabis on healthy populations and clinical psychiatric samples will be discussed, focusing primarily on anxiety and mood disorders.

Clinical/Therapeutic Approaches for Cannabinoid Ligands in Central and Peripheral Nervous System Diseases: Mini Review

OBJECTIVE

Cannabinoids, the components of Cannabis sativa Linnaeus, interact with CB1 and CB2 receptors, which are located both in the central nervous system and in the periphery and thus may exert a widespread biological activity in the body. The main medicinal properties of cannabinoids include analgesic, anti-inflammatory, antitumor, appetite stimulation, antiemesis, and muscle relaxation effects. This mini review aims to explore existing clinical trials that investigated the use of cannabinoids in diseases affecting the nervous system.

METHODS

We reviewed recent studies of cannabinoid-based therapy for disorders affecting central and peripheral nervous system in human subjects.

RESULTS

There is evidence that cannabinoid-based drugs may effectively control some symptoms associated with nervous system dysfunction, especially various types of pain and neurologic disorders, although studies are limited.

CONCLUSIONS

The efficacy of cannabinoid drugs in the treatment of nervous system diseases should be verified in future large-scale randomized clinical trials.

Parent Coping With Adolescent Trichotillomania

Adolescents who struggle with trichotillomania (TTM; hairpulling disorder) are not alone, their parents also struggle. The focus of this qualitative study was to identify what parents (N = 30) perceive as stressful about parenting an adolescent with TTM and how they cope with these stressors. Parents described uncertainty about the course of the disorder and powerlessness in the ability to protect their adolescent from the reactions of others or assist them in curtailing the hairpulling as very distressing. Data analysis revealed eight coping strategies used to manage these stressors and the accompanying grief: (a) information gathering, (b) anticipatory guidance, (c) crying, (d) hypervigilance, (e) gaining emotional support from others, (f) acceptance, (g) goal revision, and (h) guiding rather than protecting their adolescent. The study findings can be used by school nurses to gain a deeper understanding of this disorder and to provide family-centered care in the school setting.

Trichotillomania

Trichotillomania, characterized by the repetitive pulling out of one’s own hair leading to hair loss and functional impairment, has been documented in the medical literature since the 19^th century, but has received scant research attention. Community prevalence studies suggest that trichotillomania is a common disorder with point prevalence estimate of 0.5% to 2.0%. Although recently grouped with OCD in the DSM-5, clinicians need to be aware that trichotillomania and OCD may have less in common than originally thought. In fact, approaches to treating trichotillomania, which include habit reversal therapy and medication (n-acetyl cysteine or olanzapine), are quite different from those used to treat OCD; and some first-line treatments used for OCD appear ineffective for trichotillomania. Based on our clinical experience and research findings, the article recommends several management approaches to trichotillomania.

Review of available studies of the neurobiology and pharmacotherapeutic management of trichotillomania

Trichotillomania (TTM) is a psychiatric disorder characterized by an irresistible urge to pull out one's hair. Currently there are no FDA approved treatments for TTM, which makes it difficult for clinicians to select an appropriate therapeutic plan. The clinical studies that have been performed do not provide sufficient or consistent evidence regarding which drug classes should be administered. Unfortunately, most of the available data consist of case reports and clinical trials with limited sample size. This review provides an overview of currently available clinical literature that targets TTM. A summary of clinical trials as well as case reports is provided. The most common rating scales used for clinical assessment are also reviewed. The etiology of TTM remains unclear. Studies that examine various neuroanatomical, neurobiologic, as well as genetic factors associated with TTM are thoroughly discussed in this review. It is evident that clear understanding of TTM is crucial to provide better recognition, assessment, and treatment to patients of this disorder. Finally, despite research efforts for establishing pharmacological options for treatment, it is clear that new targets are warranted in order to ensure a clinically supported effective pharmacological approach to treat TTM.

Adult neurogenesis and mental illness

Several lines of evidence suggest that adult neurogenesis, the production of new neurons in adulthood, may play a role in psychiatric disorders, including depression, anxiety, and schizophrenia. Medications and other treatments for mental disorders often promote the proliferation of new neurons; the time course for maturation and integration of new neurons in circuitry parallels the delayed efficacy of psychiatric therapies; adverse and beneficial experiences similarly affect development of mental illness and neurogenesis; and ablation of new neurons in adulthood alters the behavioral impact of drugs in animal models. At present, the links between adult neurogenesis and depression seem stronger than those suggesting a relationship between new neurons and anxiety or schizophrenia. Yet, even in the case of depression there is currently no direct evidence for a causative role. This article reviews the data relating adult neurogenesis to mental illness and discusses where research needs to head in the future.