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Statistics on prevalence, for a medical condition, are of interest for many types of people.
People with a condition capable of causing shame or embarrassment may be reluctant to mention it, thus causing an under-reporting of the condition. But they may wish to seek, or readily believe, statistics which overstate the prevalence, if this helps them feel less isolated or alone. In any case they will certainly be interested in survey results.
People not directly involved can use prevalence as a guide to an appropriate level of interest. Is this a condition which they are likely encounter in people, and about which they may need to be knowledgeable? Or is it so rare that it is unlikely to be encountered by most people?
Family doctors can cross-check the prevalence at their local practice. If the local prevalence is particularly high or low, compared with national statistics, then there may be local factors operating which need to be taken into account.
Medical researchers and Government funding agencies use the prevalence statistics to allocate funds among competing research projects and other priorities.
Central to the collection of such statistics is the availability of clear and relevant diagnostic criteria, and medical practitioners skilled in their application. This is particularly important with a condition where the accompanying feelings can be varied and intense, and where there is a wide spectrum of associated behaviours.
The survey results quoted below are a brief compilation from reviews of the topic by F.I. Penzel (2000) and the chapter by G.A. Christenson and C.S. Mansueto in the book by D.J. Stein et al (1999).
This represents an extensive review of literature describing surveys of prevalence. It can be readily seen that surveys have important differences in the extent to which they apply the diagnostic criteria for trichotillomania. For your reference I have appended these criteria.
Four surveys apparently applied the criteria in an appropriate manner, and seem satisfactory in other respects. These were Anderson and Dean (1956) with 0.6%; Mannino and Delgado (1969) with 0.5%; Christenson et al (1991) with 0.6%; and Rothbaum et al (1993) with 1%.
Two other surveys are interesting at this point. Schachter (1961) reported 0.05% among children with reported psychiatric disorders; but for the sake of the current discussion this cannot be regarded as a normal population. Reeve et al (1992) reported 10%, but with a very small sample, of 10.
Also of interest is that a much larger proportion of people report hair pulling on a regular basis, and is presumably troubled by it, but which did not meet the criteria in all respects.
It is hoped that these surveys will be continued, and that criteria can be developed to assist many of those not covered by the current DSM-IV.
Anderson and Dean (1956), Number in the study (N) = 500
0.6% - of cases at a child guidance clinic
Schachter (1961), N=10,000
0.05% - Children with reported psychiatric disorders
Mannino and Delgado (1969), N=1368
0.5% - Children seen at their Mental Health Study Center
Azrin and Nunn (1978), No study
4% - Not factual data. Based on subjective impressions arising from their
clinical observations.
Christenson et al (1991), N=2579
0.6% - of college students had met the criteria at some time in their
lives. Criteria strictly applied.
2.5% - Did not necessarily experience prior urges, or post-pulling relief
or gratification
Reeve et al (1992), N=10
10% - of child and adolescent hair pullers met the formal criteria. Small
sample.
Rothbaum et al (1993), N=490
10% - Survey of University students. Reported "non-cosmetic hair-pulling"
on a regular basis.
2% - Reported resultant baldness or bald spots.
2% - Reported emotional distress as a result of pulling
1% - Reported regular pulling, and bald spots and distress
Rothbaum et al (sister study) (1993), N=221
13% - Survey of University students. Reported hair-pulling on a regular basis.
1% - Reported baldness or bald spots.
1% - Reported emotional distress as a result of pulling
Graber and Arndt (1993), N=98
11% - University undergraduates reporting hair-pulling; but there was no
clarification of the degree of hair loss or associated distress.
Graber and Arndt (1993), N=218
4% - Shopping center survey. People reported hair pulling but there was
no clarification of the degree of hair loss or associated distress.
Stanley et al (1994), N=288
15.3% - University students. Reported at least some hair pulling during the
previous year
3% - Reported at least some hair pulling on a daily basis, but no
visible hair loss was reported.
Stanley et al (1995), N=165
13.3% - University students. Non-clinical hair pulling, but it was unclear
to what extent the students would have met the criteria for trichotillomania.
A. Recurrent pulling out of one's hair resulting in noticeable hair loss.
B. An increasing sense of tension immediately before pulling out the hair or when attempting to resist the behavior.
C. Pleasure, gratification, or relief when pulling out the hair.
D. The disturbance is not better accounted for by another mental disorder and is not due to a general medical condition (e.g., a dermatological condition).
E. The disturbance causes clinically significant distress or impairment in social, occupational, or other important areas of functioning.
Source. Reprinted from Diagnostic and Statistical Manual of Mental Disorders, 4th Edition. Washington, DC, American Psychiatric Association, 1994. Copyright 1994, American Psychiatric Association.
Anderson and Dean (1956), Reported in Winchel, R.M.; Jones, J.S.; Molcho, A.; Parsons, B.; Stanley, B. and Stanley, M. (1992), "The Psychiatric Institute Trichotillomania Scale (PTS).", Psychopharmacol Bull. 1992; 28, p.463-466. (Refer Penzel reference 18)
Azrin, N.H. and Nunn, R.G. "Habit control in a day.", New York, NY: Simon & Schuster; 1978. (Refer Penzel reference 20)
Christenson, G.A.; Pyle, R.L. and Mitchell, J.E. (1991) "Estimated lifetime prevalence of trichotillomania in college students." J Clin Psychiatry 52:415-417, 1991. (Refer Stein p.6)
Christenson, G.A. and Mansueto, C.S. (1999), "Trichotillomania: Descriptive characteristics and phenomenology". Chapter in the book "Trichotillomania", edited by D.J. Stein et al. 1999.
Graber, J. and Arndt, W.B. (1993) "Trichotillomania.", Compr. Psychiatry. 34:340-346, 1993 (Refer Stein p.7)
Mannino FV, Delgado RA. (1969) "Trichotillomania in children: a review.", Am. J. Psychiatry. 1969;126:505-511. (Refer Penzel reference 03)
Penzel, F.I. (2000) "Trichotillomania: Recognition and Treatment", Medscape Mental Health 5(1), 2000.
Reeve, E.A.; Bernstein, G.A., and Christenson, G.A.. (1992), "Clinical characteristics and psychiatric comorbidity in children with trichotillomania.", J. Am. Acad. Child. Adolesc. Psychiatry. 1992; Vol. 31(1), p.132-137. (Refer Penzel reference 10)
Rothbaum, B.O.; Shaw, L.; Morris, R, et al. (1993), "Prevalence of trichotillomania in a college freshman population (letter)", J. Clin. Psychiatry 54:72, 1993. (Refer Stein p.6)
Schachter M. (1961) "Zum problem der kindlichen trichotillomania. Praxis. Kinderpsychol. Kinderpsychiatr.", 1961;10:120-124. (Refer Penzel reference 19)
Stanley, M.A.; Borden, J.W.; Bell, G.E. et al: (1994) "Nonclinical hair-pulling: phenomenology and related psychopathology.", J. Anxiety. Disord., 8: 119-130, 1994 (Refer Stein p.6)
Stanley, M.A.; Borden, J.W.; Mouton, S.G., et al: (1995), "Nonclinical hair pulling: affective correlates and comparison with clinical samples.", Behav. Res. Ther. 33:179-186, 1995 (Refer Stein p.6)
Stein, D.J.; Christenson G.A. and Eric Hollander (Eds.), (1999), "Trichotillomania", American Psychiatric Press, 1999