Effectiveness of speech therapy in adults with intellectual disabilities.

BACKGROUND: This study investigated the effect of speech therapy in a heterogeneous group of adults with intellectual disability. METHOD: Thirty-six adults with mild and moderate intellectual disabilities (IQs 40-70; age 18-40 years) with reported poor speech intelligibility received tailored training in articulation and listening skills delivered in two 3-month periods. Pre- to post-changes in speech intelligibility and receptive vocabulary were assessed using standardized tasks. RESULTS: The results showed a positive effect of treatment on speech intelligibility and receptive vocabulary, irrespective of severity of intellectual disability, hearing loss and intellectual disability aetiology. CONCLUSIONS: Speech therapy for people with intellectual disability can be effective at adult age and hearing loss should not prevent treatment. Continued attention to speech can help augment verbal communication skills in this population.

Speech Characteristics and Intelligibility in Adults with Mild and Moderate Intellectual Disabilities.

PURPOSE: Adults with intellectual disabilities (ID) often show reduced speech intelligibility, which affects their social interaction skills. This study aims to establish the main predictors of this reduced intelligibility in order to ultimately optimise management. METHOD: Spontaneous speech and picture naming tasks were recorded in 36 adults with mild or moderate ID. Twenty-five naïve listeners rated the intelligibility of the spontaneous speech samples. Performance on the picture-naming task was analysed by means of a phonological error analysis based on expert transcriptions. RESULTS: The transcription analyses showed that the phonemic and syllabic inventories of the speakers were complete. However, multiple errors at the phonemic and syllabic level were found. The frequencies of specific types of errors were related to intelligibility and quality ratings. CONCLUSIONS: The development of the phonemic and syllabic repertoire appears to be completed in adults with mild-to-moderate ID. The charted speech difficulties can be interpreted to indicate speech motor control and planning difficulties. These findings may aid the development of diagnostic tests and speech therapies aimed at improving speech intelligibility in this specific group.

Dysfluencies in the speech of adults with intellectual disabilities and reported speech difficulties.

BACKGROUND: In individuals with an intellectual disability, speech dysfluencies are more common than in the general population. In clinical practice, these fluency disorders are generally diagnosed and treated as stuttering rather than cluttering. PURPOSE: To characterise the type of dysfluencies in adults with intellectual disabilities and reported speech difficulties with an emphasis on manifestations of stuttering and cluttering, which distinction is to help optimise treatment aimed at improving fluency and intelligibility. METHOD: The dysfluencies in the spontaneous speech of 28 adults (18-40 years; 16 men) with mild and moderate intellectual disabilities (IQs 40-70), who were characterised as poorly intelligible by their caregivers, were analysed using the speech norms for typically developing adults and children. The speakers were subsequently assigned to different diagnostic categories by relating their resulting dysfluency profiles to mean articulatory rate and articulatory rate variability. RESULTS: Twenty-two (75%) of the participants showed clinically significant dysfluencies, of which 21% were classified as cluttering, 29% as cluttering-stuttering and 25% as clear cluttering at normal articulatory rate. The characteristic pattern of stuttering did not occur. CONCLUSION: The dysfluencies in the speech of adults with intellectual disabilities and poor intelligibility show patterns that are specific for this population. Together, the results suggest that in this specific group of dysfluent speakers interventions should be aimed at cluttering rather than stuttering. LEARNING OUTCOMES: The reader will be able to (1) describe patterns of dysfluencies in the speech of adults with intellectual disabilities that are specific for this group of people, (2) explain that a high rate of dysfluencies in speech is potentially a major determiner of poor intelligibility in adults with ID and (3) describe suggestions for intervention focusing on cluttering rather than stuttering in dysfluent speakers with ID.

Chromosome 1p21.3 microdeletions comprising DPYD and MIR137 are associated with intellectual disability.

BACKGROUND: MicroRNAs (miRNAs) are non-coding gene transcripts involved in post-transcriptional regulation of genes. Recent studies identified miRNAs as important regulators of learning and memory in model organisms. So far, no mutations in specific miRNA genes have been associated with impaired cognitive functions. METHODS AND RESULTS: In three sibs and two unrelated patients with intellectual disability (ID), overlapping 1p21.3 deletions were detected by genome-wide array analysis. The shortest region of overlap included dihydropyrimidine dehydrogenase (DPYD) and microRNA 137 (MIR137). DPYD is involved in autosomal recessive dihydropyrimidine dehydrogenase deficiency. Hemizygous DPYD deletions were previously suggested to contribute to a phenotype with autism spectrum disorder and speech delay. Interestingly, the mature microRNA transcript microRNA-137 (miR-137) was recently shown to be involved in modulating neurogenesis in adult murine neuronal stem cells. Therefore, this study investigated the possible involvement of MIR137 in the 1p21.3-deletion phenotype. The patients displayed a significantly decreased expression of both precursor and mature miR-137 levels, as well as significantly increased expression of the validated downstream targets microphthalmia-associated transcription factor (MITF) and Enhancer of Zeste, Drosophila, Homologue 2 (EZH2), and the newly identified target Kruppel-like factor 4 (KLF4). The study also demonstrated significant enrichment of miR-137 at the synapses of cortical and hippocampal neurons, suggesting a role of miR-137 in regulating local synaptic protein synthesis machinery. CONCLUSIONS: This study showed that dosage effects of MIR137 are associated with 1p21.3 microdeletions and may therefore contribute to the ID phenotype in patients with deletions harbouring this miRNA. A local effect at the synapse might be responsible.