Relationships between visual-motor and cognitive abilities in intellectual disabilities.

The neurobiological hypothesis supports the relevance of studying visual-perceptual and visual-motor skills in relation to cognitive abilities in intellectual disabilities because the defective intellectual functioning in intellectual disabilities is not restricted to higher cognitive functions but also to more basic functions. The sample was 102 children 6 to 16 years old and with different severities of intellectual disabilities. Children were administered the Wechsler Intelligence Scale for Children, the Bender Visual Motor Gestalt Test, and the Developmental Test of Visual Perception, and data were also analysed according to the presence or absence of organic anomalies, which are etiologically relevant for mental disabilities. Children with intellectual disabilities had deficits in perceptual organisation which correlated with the severity of intellectual disabilities. Higher correlations between the spatial subtests of the Developmental Test of Visual Perception and the Performance subtests of the Wechsler Intelligence Scale for Children suggested that the spatial skills and cognitive performance may have a similar basis in information processing. Need to differentiate protocols for rehabilitation and intervention for recovery of perceptual abilities from general programs of cognitive stimulations is suggested.

Psychiatric syndromes comorbid with mental retardation: differences in cognitive and adaptive skills.

The study concerns the specific cognitive and adaptive skills of persons dually diagnosed with mental retardation (MR) and comorbid pathologies, as schizophrenia, personality and mood disorders, pervasive developmental disorders, epilepsy and ADHD. The sample was composed of 182 subjects, diagnosed as mild or moderate MR level, age range from 6 years 8 months to 50 years 2 months, mean age 17.1 (standard deviation 7.9). All the subjects were inpatients in a specialized structure for the diagnosis and the treatment of MR. The instruments of the study were Wechsler Intelligence Scale (WAIS-R or WISC-R according to the chronological age of subjects) and Vineland Adaptive Behavior Scale (VABS). Results confirm that comorbidity is a factor differentiating among mentally retarded subjects. Both verbal processes requiring memory retrieval and visuo-spatial processes are involved as differentiating features. ADHD strongly increases the impairment of cognitive skills, while behavioral disorders are less damaging in MR performance. In adult samples, the differentiating role of comorbid syndromes in MR individuals is reduced for cognitive skills, and limited to some basic verbal abilities, more impaired in mood disorder, less in schizophrenic disorder. The areas of adaptation and socialization, motor and daily living skills, are impaired more in generalized development disturbances than in comorbid schizophrenic and personality and mood disorders. An accurate psychological assessment of dual diagnoses is useful in detecting the specific underlying processes differentiating the comorbid syndromes, and in planning an appropriate rehabilitative treatment.

Factor analysis of Wechsler Adult Intelligence Scale-Revised in developmentally disabled persons.

The results of previous studies on the factorial structure of Wechsler Intelligence Scales are somewhat inconsistent across normal and pathological samples. To study specific clinical groups, such as developmentally disabled persons, it is useful to examine the factor structure in appropriate samples. A factor analysis was carried out using the principal component method and the Varimax orthogonal rotation on the Wechsler Adult Intelligence Scale (WAIS-R) in a sample of 203 developmentally disabled persons, with a mean age of 25 years 4 months. Developmental disability ranged from mild to moderate. Partially contrasting with previous studies on normal samples, results found a two-factor solution. Wechsler's traditional Verbal and Performance scales seems to be more appropriate for this sample than the alternative three-factor solution.

Psychopathology and mental retardation: a study using the Rorschach Inkblot Test.

The aim of this research was to study the psychological effects of disorders such as schizophrenia and depression associated with mental retardation. The Rorschach Inkblot Test and the Wechsler Adult Intelligence Scale were administered to a group of 97 subjects (52 women and 45 men) ages 15:10 yr. to 36:6 yr. (M=21:5, SD=5:3). The subjects were divided into four subgroups according to the presence or absence of mental retardation and psychiatric diagnosis (schizophrenia versus depression). The quality of the perception in Rorschach responses and the ErlebnisTypus scores differentiated psychotic and depressed subjects well. These disorders, when associated with mental retardation, make impairment of perceptual performance worse. The interaction between Axis I mental disorders (according to DSM-IV diagnosis) and mental retardation, an Axis II disorder, is discussed.