Prioritising Cases with Early Language Delay

Causality

Causality refers to a cause-effect relationship where one event leads to another. However, language development is complex and not easily predicted, so we use risk factors instead.

Risk factor

A variable associated with increased risk of a disorder. It is correlational, not necessarily causal

Additivr risk

Additive risk is the concept that having more risk factors increases the likelihood of a language difficulty

Who are late talkers?

Children around 2 years old with no other diagnoses who fall in the 10th percentile for expressive vocabulary, have fewer than 50 words, and no two-word combinations. Comprehension delays may be present but are not part of the definition.

Verbal working memory

The system for storing and processing verbal information, essential for understanding new and complex language. Example task to assess VWM: answering T/F phrases and repeating the last word of the phrase, increasing the number of phrases each time.

Phonological short term memory

A specialised short term memory system which sets up long term representations of phonological forms

• storage and rehearsal

• necessary for learning new vocab and recalling sentences

Example task to assess PSTM: repeating nonsense words with increasing syllables.

Theory of multiple underlying cognitive processing deficits

That DLD results from multiple underlyin cognitive processing difficulties (e.g., poor VWM, phonological STM, and processing speed).

Not all individuals with DLD have all deficits, but more deficits increase likelihood. 

the more processing difficulties you have, the more likely to have DLD = multiple underlying difficulties.

Development trajectories of growth in language for 2–4-year-olds with no clear biomedical cause

• Start slow and catch up 

• Continue with slow development ---> DLD/LD 

• Can begin with EL in typical range but then slow in their development ---> DLD/LD 

• Start with typical EL and continue to develop typically 

Clinical implications for different development trajectories

• Currently SLTs don't have enough info to predict which late talkers will catch up and which ones will have varying levels of difficulty with language

• There are too many late talkers to see in clinic so we need to prioritise

• We don't know how to identify those who will start strong and then slow in their language development over time early 

Key indicators of stronger language development - parent child interaction

1. responsivity

2. variety and complexity of linguistic input (quality)

3. quantity of linguistic input

Verbal responsivity

The caregiver's consistent, warm, and contingent responses to a child's communication signals

Quality of linguistic input

The use of varied, rich, and developmentally appropriate vocabulary and sentence structures.

Quantity of linguistic input

The amount of spoken language a child hears. This is important, but quality matters more.

Types of risk factors

Behavioural factors = overt differences in behaviour that characterise the disorder, what the child does 

Environmental factors = external experiences which increase or decrease the risk in the face of the biological risk 

Biological factors = differences in genetic risk and neurological structures associated with the disorder 

Cognitive factors = differences in perception and information processing associated with the disorder 

Late talkers’ key risk factors for ongoing language difficulties

• Poor language comprehension (especially syntax)

• Reduced gesture use

• Delayed symbolic play

• Delayed social skills

• Poor general development (motor, cognitive, social)

• Poor word learning when taught

• Delayed word combinations

• Poor linguistic input / quality of interactions

• Positive family history of language/literacy difficulties

Environmental factor: Poor linguistic input/quality of interactions - subfactors

Directive style of interaction/low responsivity & low linguistic input

• SES

• parents with no formal qualifications

• poor quality early childhood care

• abuse/neglect

• excessive screen time

• otitis media

• birth order/number of siblings

• mother's mental health

Late talkers’ weak predictors/risk factors for ongoing language difficulties

• Sex

• Late expressive vocabulary (on its own)

• Cognitive processing before age 4

Multiple factors interact

• No single factor is sufficient on its own to predict DLD

• The more risk factors = the greater the risk