Comprehensive Guide to Stuttering: Genetics, Types, and Assessment

Genetic factors

60-70% of PWS have a family history.

Guitar's model

Inherited/congenital predisposition appears when child learns complex speech/language coordination.

Boehme (1968)

24% of 313 children with brain damage at birth developed stuttering.

Poulos & Webster (1991)

Among PWS with no family history, 37% reported congenital factors (vs. only 2.4% with family history).

Congenital factors examples

Anoxia at birth, premature birth, head injury, mild CP, mild developmental disability.

Spontaneous recovery

Common, especially with no family history or all recovered relatives.

Fluency (Starkweather, 1987)

Temporal aspects of speech including pauses, rhythm, intonation, stress, rate.

Disfluency

Interruptions in speech flow that can be normal (typical) or abnormal (atypical).

Stuttering

Specific interruptions in PWS characterized by abnormally high frequency/duration of stoppages in forward flow of speech.

Core behaviors of stuttering

Repetitions (phrase, word, syllables, phoneme), prolongations, blocks.

Iceberg Model

Layers of stuttering: core behaviors, secondary behaviors, emotions & attitudes.

Prevalence

How many people currently stutter (-1% school aged; lower in adults; varies by age/definitions).

Incidence

How many people have ever stuttered at some point (-5% for cases lasting longer).

Onset of stuttering

Usually occurs between 2 to 5 years, tied to spoken language use.

Recovery without treatment

Ranges from 20 to 80%; longitudinal studies show 75% recovery.

Factors favoring recovery

No relatives who stutter, earlier onset, stronger phonological/language skills, higher nonverbal IQ, female, right-handed.

Persistence risk factors

Family history, later onset, male, tension/secondary behaviors, awareness/frustration.

Sex Ratio in stuttering

3:1 M:F overall; increases with age (3:1 in 1st grade to 5:1 in 5th).

Language factors in PWS

Adults & elementary kids focus on consonants, word-initial, content words; preschoolers focus on pronouns/conjunctions.

Anticipation effect

PWS can predict which words they will stutter on right before speaking.

Consistency effect

Same words stuttered across multiple readings of a passage.

Adaptation effect

Fewer stutters on the same passage across multiple readings.

Fluency-Enhancing Conditions

Conditions studied include relaxed speaking, choral speaking, rhythmic speaking, and singing.

Typical stuttering

Childhood onset, core + secondary behaviors evolve, strong genetic link, adaptation/consistency effects present.

Atypical stuttering

Includes neurogenic, psychogenic, and cluttering types with different characteristics.

Stages of stuttering

Normal disfluency, borderline, beginning, intermediate, advanced.

Assessment tools

Include speech samples, SSI-4, attitude/impact scales, and case history.

Counting disfluencies

Includes total disfluencies, stutter-like disfluencies, and speaking rate.