Barbering in mice: a model for trichotillomania
BMJ 2005; 331 doi: https://doi.org/10.1136/bmj.331.7531.1503 (Published 22 December 2005) Cite this as: BMJ 2005;331:1503
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While trichotillomania (TTM) is predominantly a self-directed
behavior, mouse barbering is not (1,2). In many cases barbering is a
complex social behavior with multiple contexts and purposes (2).
Interestingly, observing a big number of individually housed mice of
different strains in 2 colonies during the last 4 years, we saw no self-
barbering in our mice. Although the possibility that barbering is a form
of TTM (3,4) seems indeed tempting, this theory is not supported by
available behavioral literature, and may therefore be misleading. We shall
not consider barbering as always "pathological", and shall focus instead
on why some happy mice still barber each other. Finally, do we really know
that barbering (possibly, evolving from hetero-grooming) does not occur in
the wild nature - as a part of animal's normal behavior?
References
1. Sarna JR, Dyck RH, Whishaw IQ. The Dalila effect: C57BL6 mice
barber whiskers by plucking. Behav Brain Res 2000; 108:39-45.
2. Kalueff AV, Minasyan A, Keisala T, Shah ZH, Tuohimaa P. Hair
barbering in mice: implications for neurobehavioural research. Behav
Processes 2006; 71:8-15.
3. Garner JP, Weisker SM, Dufour B, Mench JA. Barbering (fur and
whisker trimming) by laboratory mice as a model of human trichotillomania
and obsessive-compulsive spectrum disorders. Comp Med 2004; 54:216-24.
4. Kurien BT, Gross T, Scofield RH. Barbering in mice: a model for
trichotillomania. BMJ 2005; 331:1503-5.
Competing interests:
None declared
Competing interests: No competing interests
We appreciate the comments of the authors (1) regarding our article
"Barbering in mice: a model of trichotillomania (2).
The authors have made the following statement in their response -
"One of the differences the authors point out is the absence of
ruminations". We wish to point out that this statement is not entirely
correct since we have stated the following in our manuscript - "...there
is the absence of obsessive rumination...". We believe that the word
"obsessive", which the authors have left out, is important in this
context.
Secondly, we agree entirely with the statement of the authors "that
at least some patients with trichotillomania meet the additional
diagnosis of Obsessive Compulsive Disorder". In fact, we have also pointed
out that there is overlapping phenomenology as well as differences between
trichotillomania and obsessive compulsive disorder.
References
1. Basil B, Mathews M, Adetunji B, Budur K. Is Trichotillomania an
Obsessive Compulsive Disorder? BMJ.com, 27 December, 2005
2. Kurien BT, Gross T, Scofield RH. Barbering in mice: a model for
trichotillomania. BMJ. 2005 Dec 24;331(7531):1503-5.
Competing interests:
None declared
Competing interests: No competing interests
The authors of the article ‘Barbering in mice: a model for
trichotillomania’ state that in spite of overlapping phenomenology, there
are important differences between trichotillomania and Obsessive
Compulsive Disorder. One of the differences the authors point out is the
absence of ruminations (1).
The phenomenology of trichotillomania differs from person to person.
The characteristic feature of trichotillomania is the recurrent pulling
out of one’s own hair, which results in noticeable hair loss (2). The
sites of hair pulling can vary and can include any region of the body in
which hair may grow. It can be isolated brief episodes or those that occur
over a considerable period of time. Hair pulling has been described to
occur in states of relaxation and distraction and also during stressful
circumstances (2). In some people with trichotillomania, they have an
irresistible urge to pull the hair and leads to tension or anxiety if they
resist this urge. They get pleasure, gratification, or relief when pulling
out the hair.
Obsessions are recurrent and persistent thoughts, impulses, feelings,
idea, sensations or images (2,3). Compulsion is a pathological need to act
on the impulse that, if resisted produces anxiety (3). It has also been
defined as repetitive behaviors that the person feels driven to perform in
response to the obsession (2). In trichotillomania the obsession is the
recurrent urge or impulse to pull out one’s hair. The patient responds to
this urge by pulling out the hair. Resistance to this urge to pull out the
hair results in anxiety or tension. This can be described as the
compulsion in trichotillomania. Many patients with trichotillomania
recognize that this urge to pull out the hair and is excessive or
unreasonable.These impulses and behaviors cause marked distress to some of
these patients.
So we believe that at least some patients with trichotillomania meet
the additional diagnosis of Obsessive Compulsive Disorder.
References:
1. Kurien BT, Gross T, Scofield RH. Barbering in mice: a model for
trichotillomania. BMJ. 2005 Dec 24;331(7531):1503-5.
2. American Psychiatric Association. Diagnostic and Statistical
Manual of Mental Disorders- Text Revision (DSM-IV-TR). 2000.
3. Sadock B J, Sadock VA (Eds). Comprehensive Textbook of Psychiatry.
LWW 2000.
Competing interests:
None declared
Competing interests: No competing interests
Diagnosis of trichotillomania
Compulsive hair pulling in humans is known as trichotillomania (TTM).
The aetiology of TTM is not known. Although the striatum, orbitofrontal
cortex and anterior cingulate cortex appear to play a role in obsessive-
compulsive disorder (OCD), the neural defects involved in TTM are not
known (1). As hair can represent beauty, virility and sexuality,
psychoanalysts point to TTM as a form of castration (2). Childhood TTM is
thought to be simply a manifestation of psychosocial stress within the
family unit (moving to a new house, hospitalizations, periods of
separation, disturbed mother-child relationship)(3,4). A dermatologist
who diagnoses TTM could greatly benefit by referring their patient to a
psychiatrist, since major depression, social or simple phobias and OCD are
some of the debilitating psychopathologies that may be present in
trichotillomanics (5). Dopaminergic, serotonergic and opioid neurochemical
systems have been implicated in the neurobiological basis of TTM (5).
According to one study, 40% of trichotillomanics had never been
diagnosed and 58% had never been treated, suggesting that TTM may be under
diagnosed in adult patients (6). Physical examination, along with
psychiatric history as part of a thorough past medical history, may
suggest a diagnosis of TTM. Adult patients tend to use head covering, wigs
and avoid swimming in an effort to keep their hair loss a secret (3,5,7).
Most trichotillomanics have been shown to admit to hair-pulling if asked
by an empathetic physician (8). Scalp biopsy could be useful for TTM
diagnosis, especially in the case of mentally impaired patients and young
children who are unable to communicate (8).
Therapy for trichotillomania
TTM originating in early childhood is considered a habit disorder
akin to thumbsucking (3,5). This type of TTM usually disappears by the
time the child attains school age. Children with TTM originating during
school years should be considered for behavioural therapy (positive
reinforcement, punishment procedures, habit reversal training) under a
psychiatrist’s supervision. Behavioural therapy is considered to be more
efficacious than pharmacotherapy in children (3,5,9). For adolescents and
adults, a combination of behavioural therapy and pharmacotherapy would be
the most beneficial clinically (10). Although long-term data are not
available regarding their efficacy, at present, selective serotonin re-
uptake inhibitors (SSRIs) are the most popular medications available for
the treatment of TTM (5). Similarly, the neuroleptic haloperidol (11),
the tricyclic antidepressant amitriptyline, the serotonin and
norepinephrine selective reuptake inhibitor venlafaxine, the monoamine
oxidase inhibitor isocarboxazid, the mood stabilizer lithium, the opiate
antagonist naltrexone and the anxiolytic clonazepam have also been used
successfully in minor clinical trials (5).
References
1. Reilly CE. Disruption of Hoxb8 gene leads to obsessive grooming
behavior. J Neurol.2002; 249:499-501.
2. Krishnan KR, Davidson JR, Guajardo C.Trichotillomania--a review.
Compr.Psychiatry 1985; 26:123-8. Review.
3. O'Sullivan RL, Keuthen NJ, Christenson GA, Mansueto CS, Stein DJ,
Swedo SE.Trichotillomania: behavioral symptom or clinical syndrome? Am J
Psychiatry. 1997;154:1442-9.
4. Oranje AP, Peereboom-Wynia JD, De Raeymaecker DM. Trichotillomania
in childhood. J Am Acad Dermatol 1986; 15:614-9.
5. Papadopoulos AJ, Janniger CK, Chodynicki MP, Schwartz RA.
Trichotillomania. Int J Dermatol. 2003 42:330-4. Review.
6. Cohen LJ, Stein DJ, Simeon D, Spadaccini E, Rosen J, Aronowitz B
et al. Clinical profile, comorbidity, and treatment history in 123 hair
pullers: a survey study. J Clin Psychiatry 1995; 56:319-26.
7. Christenson GA, O’Sullivan RL. Trichotillomania: rational
treatment options. CNS Drugs 1996; 6:23-34.
8. Christenson GA, Crow SJ. The characterization and treatment of
trichotillomania. J Clin Psychiatry. 1996;57 Suppl 8:42-7; discussion 48-
9. Review.
9. Peterson AL, Campise RL, Azrin NH. Behavioral and pharmacological
treatments for tic and habit disorders: a review. J Dev Behav Pediatr
1994;15:430-41. Review.
10. Keuthen NJ, O'Sullivan RL, Goodchild P, Rodriguez D, Jenike MA,
Baer L. Retrospective review of treatment outcome for 63 patients with
trichotillomania. Am J Psychiatry 1998;155:560-1.
11. Fenton M Coutinho ES Campbell C. Zuclopenthixol acetate in the
treatment of acute schizophrenia and similar serious mental illnesses.
Cochrane Database Syst Rev. 2001;(3):CD000525. Review.
Competing interests:
None declared
Competing interests: No competing interests
Dear Sir/Madam,
My first name has been left out in the list of authors of this paper
on the BMJ web site. Please add 'Biji' to "T. Kurien. My name should read
Biji T. Kurien, instead of just T. Kurien.
My name is correct in the PDF version of the paper.
Thanks
Sincerely,
Biji T. Kurien
Competing interests:
None declared
Competing interests: No competing interests
Barbering does not appear to be a "normal" behavior.
Dr. Kalueff points out (1) that barbering in mice is only partner-
directed and not self-directed. However, current evidence points to the
fact that self-directed barbering occurs in mice as well as in other
animals.
Barbering in mice can be both self-directed or partner directed (2).
The incidence of self-directed barbering was found to be 5.7% in 88 single
-caged animals compared to 0.6% in 1891 group/pair-housed mice. Partner-
directed barbering was found to be 7.5% in the group/pair housed mice (3).
Hox 8 mutants housed individually also demonstrate self-directed barbering
(4,5). Barbering is one of the most pervasive behavioral problems in
single-caged non-human primates, so much so that some subjects over groom
to the point of almost total baldness (6,2). Self-directed barbering has
been observed in dogs and cats (7), single-caged rabbits (8) but not in
sheep, musk ox (9,2) or guinea pig (10). Barbering has not been reported
in gerbils, rats, voles or any other rodents (2).
Dr. Kalueff raises the interesting question as to whether barbering
occurs in the wild nature - as a part of an animal's normal behavior.
Available literature points to the fact that hair pulling or barbering in
not a normal behaviour and that it has not been documented in animals
living in a natural species-favourable environment (2). Barbering has been
catergorized as a behavioural pattern occurring in animals confined in an
artificial environment (2). Barbering in animals has been categorized by
the Institute for Laboratory Animal Research as a maladaptive behaviour
that relieves the intensity of distress resulting from the chronic
exposure to environmental stressors (11). Evidence, both clinical and
empirical, suggests that barbering could be a reflection of chronic stress
resulting from husbandry deficiencies. However, it has to be pointed out
that environmental modifications have thus far been ineffective in curing
animal subjects who have developed this behavioral pathology (2).
Barbering in mice was shown to be reduced by the provision of regularly
replaced toys. However, this practice did not eliminate barbering
completely (12).
References
(1) Kalueff AV. Is barbering a “normal” behaviour?
http://bmj.bmjjournals.com/cgi/eletters/331/7531/1503
(2) Reinhardt V. Hair pulling: a review. Lab Anim 2006; 39:361-69.
(3) Garner JP, Weisker SM, Dufour B, Mench JA. Barbering (fur and
whisker trimming) by laboratory mice as a model of human trichotillomania
and obsessive-compulsive spectrum disorders. Comp Med. 2004;54:216-24.
(4) Kurien BT, Gross T, Scofield RH.Barbering in mice: a model for
trichotillomania. BMJ. 2005;331:1503-5.
(5) Greer JM, Capecchi MR. Hoxb8 is required for normal grooming
behavior in mice. Neuron 2002;33: 23-34.
(6) Tully LA, Jenne M, Coleman K. Paint roller and grooming-boards as
treatment for over-grooming. Contemporary topics in laboratory animal
science 2002; 41, 75.
(7) Moon-Fanelli AA, Dodman NH, O’Sullivan RL. Veterinary models of
compulsive self-grooming: parallels with trichotillomania. In:
Trichotillomania (Stein DJ, Christenson GA, Hollander E, eds). Washington,
DC: American Psychiatric Press, 1999; 63-92.
(8) Brummer H. [Trichophagy--a behavior disorder in domestic
rabbits]. Dtsch Tierarztl Wochenschr 1975;82:350-1.
(9) Done-Currie JR, Hecker JF, Wodzicka-Tomaszewka M. Behaviour of
sheep transferred from pasture to animal house. Applied animal behaviour
science 12, 121-30.
(10) Harper LV. Behaviour. In: The biology of the guinea pig (Wagner
JE, Manning PJ, eds). New York, NY: Academic Press, 1976; 31-51.
(11) Institute for Laboratory Animal Research. Recognition and
alleviation of pain and distress in laboratory animals. Washington, DC:
National Academy Press, 1992.
(12) De Luca AM. Environmental enrichment: does it reduce barbering
in mice? AWIC Newsletter 8, 7-8.
Competing interests:
None declared
Competing interests: No competing interests