Print version ISSN 0185-3325
ALBORES-GALLO, Lilia; LARA-MUNOZ, María del Carmen; MELCHOR CONTRERAS, Dea del Carmen and ANGELES ALBORES, David. Expressive vocabulary in a sample of preschoolers with psychiatric disorders and a group of children with typical development. Salud Ment [online]. 2011, vol.34, n.4, pp. 315-322. ISSN 0185-3325.
Introduction Expressive language problems are common amongst preschoolers both in the general population (15-20%) and in clinical settings (50-75%); furthermore, these problems are often not detected. Language problems require attention since they are associated with severe developmental disorders such as autism (Au), Asperger's syndrome (AS), attention-deficit hyperactivity disorder (ADHD) and mental retardation. In theory, language development, specifically expressive vocabulary, associated to psychiatric disorders could be identified with a scale that measures expressive language. Objectives 1. To determine the frequency of language delay in a sample of Mexican children with typical development in the community. 2. To determine the vocabulary level for autism, Asperger's syndrome, ADHD and other psychiatric disorders through the use of the Language Development Survey (LDS). 3. To analyze if differences in vocabulary ratings among the clinical subgroups can be detected with this instrument. Materials and methods The sample consisted of: A community group with typical development (TDG) (n=302) and a clinical group (CG) (n=55); both groups had an age range of 2-5 years. The clinical group was subdivided into 4 clinical subgroups based on DSM-IV criteria for: autism, Asperger's syndrome, ADHD and other psychiatric disorders (OPD) (enuresis, encopresis, separation anxiety). Exclusion criteria were: deafness, hypoacusia and other sensorial disorders and mental retardation. A semi-structured interview based on DSM-IV criteria was designed ad hoc to diagnose: autism, Asperger's syndrome, ADHD (inattentive, combined or hyperactive impulsive varieties), specific phobia disorder, tics (transitory, chronic and Tourette's syndrome), dysthymic disorder, depression, enuresis, separation anxiety disorder based on parent information. The clinical evaluation included a semi-structured play session with age-appropriate didactic material. Discrepancies in diagnosis were resolved by consensus. All interviews were conducted by an experienced clinician. The number of bulbs in the household was used to measure socioeconomic status (SES). The LDS is a list of words that explores children's vocabulary based upon parental report. The original survey has a Cronbach's alpha coefficient of 0.99, test-retest coefficient of 0.97-0.99, and a sensitivity and specificity of 86-90%. Language delay (LD) was defined as ≤50 words, as recommended by several researchers. All parents signed an informed consent form and answered the LDS. Statistical analysis. Categorical data was analyzed using a χ2 analysis; continuous data such as age, socioeconomic status, and LDS score, were analyzed using t-tests. To analytically compare the LDS group medians, a Kruskal-Wallis test was used, since the variable distribution violated the normality distribution requirements for parametric tests. For the post hoc tests, a Tamhane analysis was used for groups of different sizes. Differences were considered statistically significant if they had a p<0.05. Results The groups were similar for variables such as child's age, parents' age and the LDS median between the normal development group and the clinical group t(355)=1.12, p=.26. The proportion of male children was greater in the clinical group (CG) than in the TDG, 76.4% vs. 53%, χ2(1,N=357)=10.63, p<.001. SES was higher for the TDG (M=7.2, SD=4.2) than for the CG (M=5.8, SD=3), p<.005. The father's age (r=.15, p<.009), the mother's age (r=.16, p<.003) and the SES (r=.13, p<.01) were correlated to the LDS score. Additionally, father's and mother's age were strongly correlated (r=.72, p<.0001) and the mother's age showed small correlations with the socioeconomic status (r=.15, p<.004). The mother's age was correlated with the child's vocabulary for both sexes (males: r=.16, p<.04, females: r=.16, p<.02), and vocabulary was significantly correlated with the SES, only for the males. Language delay frequency in the TDG was 21.2%, and 23.6% for the CG, χ2(1,N=352)=1.03, p<0.59. By sex, males in both groups exhibited a greater frequency of LD [TDG: 21.6% males vs. 20.7% females, χ2(1,N=302)=.154, p<0.926; CG: 26.2% males vs. 15.4% females, χ2(1,N=55)=.642, p<0.423]. The autism subgroup had the lowest vocabulary rating (M=85, SD=78.68), followed by the OPD subgroup (M=149, SD=121), whose rating was very similar to the typically development group (M=179, SD=105). The Asperger group (M=259, SD=27) had a similar score to the ADHD group (M=286, SD=100.2), which had the highest vocabulary score of all. The Kruskal-Wallis test for median differences was significant [H(4)=17.47, p<.002]. Multiple contrast comparisons and Tamhane's post hoc analysis showed that only the contrast between the autism and the ADHD subgroups (means: 85 vs. 286, respectively) was significant (ANOVA Tamhane post hoc, p<.01).
Keywords : Language delay; autism, Asperger; attention deficit disorder; pervasive developmental problems.