1. Stuttering Patterns Within the Population
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2. Why study occurrence?
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3. Determining the occurrence frequency of a disorder
Source: Manitoba Centre for Health Policy
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4. What is the prevalence of Stuttering? (US studies)
Prevalence in total population: ~ 1%
Bloodstein & Ratner (2008)
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5. What is the incidence of stuttering?
More difficult to estimate as accurate numbers typically require prospective longitudinal studies.
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6. What is the incidence of stuttering?
Glasner & Rosenthal (1957)
Method: parent interview
Sample size: 996
Age range: entering 1st grade
Incidence: 15.4 %
Andrews & Harris (1964)
Method: direct observation and parent report
Sample size: 1142
Age range: 0-16 years
Incidence: 4.9 %
Sheehan and Martin (1970)
Method: interview
Sample size: 5000+
Age range: College students
Incidence: 2.9 %
Mansson (2000)
Method: direct observation
Sample size: 1040
Age range: 0-3
Incidence: 4.9 %
Craig et al. (2002)
Method: telephone survey
Sample size: 12,131
Incidence:
adults: 2.1 %
2-5 years: 2.8 %
6-10 years: 3.4 %
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7. What is the incidence of stuttering?
Mansson (2006)
Method: SLP dx
Sample size: 928
Age range: 0-3
Incidence: 17.7 %
Reilly et al. (2009, 2013)
Methods: direct observation
Samples size: 1619
Incidence:
0-3: 8.5 %
0-4: 11.2 %
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8. Reilly et al. (2013)
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9. Influential variables Family History
Bloodstein & Ratner (2008)
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10. Influential variables Family History
30-60% of PWS have a family member who stutters
< 10 % of NFS have a family member who stutters
Therefore, a positive family history for stuttering increases the risk of stuttering at least threefold.
How might we interpret this pattern?
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11. Influential variables
Age
Preschoolers at greatest risk
75% of those who stutter are doing so by age 6
Essentially 100% are doing so by age 12
How might we interpret this pattern?
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12. Influential variables
Gender
Males: female ratio: ~ 3:1
Ratio tends to get larger with age
How might we interpret this pattern?
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13. Influential variables
Geographic factors - Is stuttering Universal?
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14. Influential variables
Geographic factors
Stuttering appears in all geographic regions of the world
Solid research lacking in many areas outside the so-called ‘developed’ nations
How might we interpret this pattern?
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15. Influential variables
Cultural factors, racial factors & bilingualism
Lack of well-controlled studies
How might we interpret this pattern?
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16. Problems with defining a population
“In their own ways both the Iowa and Newcastle groups may represent rather special cases when considered in relation to the whole range of cultural variations. It must be considered that if what we have in mind as “the population” is to be defined in terms of numbers it is very possibly best represented by people who live by the handplow, whose likes have rarely been seen in all of England or the United States outside the pages of National Geographic Magazine, and who can ill afford the luxury of being concerned about their children’s stuttering.” (Bloodstein, 1995)
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17. Influential variables
Clinical populations with lower than typical stuttering prevalence
Hearing impaired (deaf)
Cleft palate
Clinical populations with higher than typical stuttering prevalence
Cognitively impaired
Down’s syndrome
ADD/ADHD?
Tourette?
OCD?
How might we interpret this pattern?
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