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Long-Term Outcome for Children With Autism Who Received Early Intensive Behavioral Treatment, American Journal on Mental Retardation, Vol.  97, No. 4, pp. 359-372, 1993

by John J. McEachin, Tristram Smith, and 0. Ivar Lovaas
University of California, Los Angeles

(For more information about The Childhood Learning Center contact the Center or http://www.tclc.com/ for further information.)

After a very intensive behavioral intervention an experimental group of 19 preschool-age children with autism achieved less restrictive school placements and higher IQs than did a control group of 19 similar children by age 7 (Lovaas, 1987). The Present study followed-up this finding by assessing subjects at a mean age of 11.5 years. Results showed that the experimental group preserved its gains over the control group, The 9 experimental subjects who had achieved the best outcomes at age 7 received particularly extensive evaluations indicating that 8 of them were indistinguishable from average children on tests of intelligence and adaptive behavior. Thus, behavioral treatment may produce long-lasting and significant gains for many young children with autism.

Infantile autism is a condition marked by severe impairment in intellectual, social, and emotional functioning. Its onset occurs in infancy, and the prognosis appears to be extremely poor (Lotter, 1978). For example, in the longest prospective follow-up study with a sound methodological design, Rutter (1970) found that only 1 of 64 subjects with autism (fewer than 2%) could be considered free of clinically significant problems by adulthood, as evidenced by holding a job, living independently, and maintaining an active and age-appropriate social life. The remaining subjects showed numerous dysfunctions, such as marked oddities in behavior, social isolation, and florid psyche pathology. The majority of subjects required supervised living conditions.
Professionals have attempted a wide variety of interventions in an effort to help children with autism. For many years, no scientific evidence showed that any of these interventions brightened the children's long term prognosis (DeMyer et al., 1981). However, since the 1360s, one of these interventions, behavioral treatment, has appeared promising. Behavioral treatment has been found to increase adaptive behaviors such as language and social skills, while decreasing disruptive behaviors such as aggression (DeMyer, Hingtgen, &Jackson, 1981; Newsom & Rincover, 1983; Rutter, 1985). Furthermore, behavioral treatment has been continuously refined and improved as a result of ongoing research efforts at a number of sites (Lovaas & Smith, 1888). Some recent evidence has indicated that behavioral treatment has developed to the point that it can produce substantial improvements in the overall functioning of young children with autism (Simeonnson, Olley, & Rosenthal, 1987). Lovaas (1987) provided approximately 40 hours per week of one-on-one behavioral treatment for a period of 2 years or more to an experimental group of 19 children with autism who were under 4 years of age. This intervention also included parent training and mainstreaming into regular preschool environments. When re-evaluated at a mean age of 7 years, subjects in the experimental group had gained an average of 20 IQ points and had made major advances in educational achievement. Nine of the 19 subjects completed first grade in regular (non special education) classes entirely on their own and had IQs that increased to the average range. By contrast, two control groups totaling 40 children, also diagnosed as autistic and comparable to the experimental group at intake, did not fare nearly as well. Only one of the control subjects (2.50/a) attained normal levels of intellectual and educational functioning.

These data suggest that behavioral treatment is effective. However, the durability of treatment gains is uncertain. In one prior major study, Lovaas, Koegel, Simmons, and Long (1973) found that children with autism regressed following the termination of treatment. Other studies have shown that children with autism may display increased difficulties when they enter adolescence (Kanner, 1971; Waterhouse & Fein, 1984). Also, as was stated in the first follow-up (Lovaas, 1987), "Certain residual deficits may remain in the normal functioning group that cannot be detected by teachers and parents and can only be isolated on closer psychological assessment, particularly as these children grow older" (p. 8). This possibility points to the need for a more detailed assessment and for continued follow-ups of the group over time.

The present investigation contained two parts: In the first part we examined whether several years after the evaluation at age 7, the experimental group in Lovaas's (1987) study had maintained its treatment gains. Subjects in the experimental group and one of the control groups completed standardized tests of intellectual and adaptive functioning. The groups were then contrasted with each other, and their current performance was compared to their performance on previous assessments. The second part of the investigation focused on those subjects who had achieved the best outcome at the end of first grade in the Lovaas (1987) study (i.e., the 9 subjects who were classified as normal functioning out of the 18 in the experimental group). We examined the extent to which these best-outcome subjects could be considered free of autistic symptomatology. A test battery was constructed to assess a variety of possible deficits: for example, idiosyncratic thought patterns, mannerisms, and interests; lack of close relationships with family and friends; difficulty in getting along with people; relative weaknesses in certain areas of cognitive functioning, such as abstract reasoning; not working up to ability in school; flatness of affect; absence or peculiarity in sense of humor. Possible strengths to be identified included normal intellectual functioning, good relationships with family members, ability to function independently, appropriate use of leisure time, and adequate socialization with peers. Numerous methodological precautions were taken to ensure objectivity of the follow-up examination.

Subjects and Background

Characteristics of the subjects and their treatment have been described elsewhere (Lovaas, 1987) and will only be summarized here. The initial treatment study contained 38 children who, at the time of intake, were very young (less than 40 months if mute, less than 46 months if echolalic) and had received a diagnosis of autism from a licensed clinical psychologist or psychiatrist not involved in the study. These 38 subjects were divided into an experimental group and a control group. The assignment to groups was made on the basis of staff availability. At the beginning of each academic quarter, treatment teams were formed. The clinic director and staff members then determined whether any opening existed for intensive treatment. If so, the next referral received would enter the experimental group; otherwise, the subject entered the control group. The experimental group contained 19 children who received 40 or more hours per week of one-to-one behavioral treatment for 2 or more years. The control group was comprised of 19 children who received a much less intensive intervention (10 hours a week or less of one-to-one behavioral treatment in addition to a variety of treatments provided by community agencies, such as parent training or special education classes). The initial study also included a second control group, consisting of 21 children with autism who were followed over time by a nearby agency but who were never referred for this study. However, these 21 subjects were not available for the present investigation. On standardized measures of intelligence, the second control group did not differ from either the experimental group or the first control group at intake, nor did it differ from the first control group when evaluated again when the subjects were 7 years old. These findings suggest that, as measured by standardized tests, (a) the children with autism who were referred to us for treatment were comparable to children with autism seen elsewhere and (b) the minimal treatment Provided to the first control group did not alter intellectual functioning.

Statistical analysis of an extensive range of pretreatment measures confirmed that the experimental group and control group were comparable at intake and closely matched on such important variables as IQ and severity of disturbance. The mean chronological age (CA) at diagnosis for subjects in the experimental group was 32 months. Their mean IQ was 53 (range 30 to 82; all IQs are given as deviation scores). The mean CA of subjects in the control group was 35 months; their mean IQ was 46 (range 30 to 80). Most of the subjects were mute, all had gross deficiencies in receptive language, none played with peers or showed age-appropriate toy play, all were emotionally withdrawn, most had severe tantrums, and all showed extensive ritualistic and stereotyped (self-stimulatory) behaviors. Thus, they appeared to be a representative sample of children with autism (Lovaas, Smith, & McEachin, 1989). Lovaas (1987) reported a more complete presentation of the intake data.

The children in the experimental group and control group received their respective treatments from trained student therapists who worked in the child's home. The parents also worked with their child, and they received extensive instruction and supervision on appropriate treatment techniques. Whenever possible, the children were integrated into regular preschools. The treatment focused primarily on developing language, increasing social behavior, and promoting cooperative play with peers along with independent and appropriate toy play. Concurrently, substantial efforts were directed at decreasing excessive rituals, tantrums, and aggressive behavior. (For a more detailed description of the intervention program, see the treatment manual [Lovaas et al., 1980] and instructional videotapes that supplement the manual [ Lovaas & Leaf, 1981].)

At the time of the present follow-up (1984-1985), the mean CA of the experimental group children was 13 years (range = 9 to 19 years). All children who had achieved normal functioning by the age of 7 years had ended treatment by that point. (Normal functioning was operationally defined as scoring within the normal range on standardized intelligence tests and successfully completing first grade in a regular, non special education class entirely on one's own.) On the other hand, some of the children who had not achieved normal functioning at 7 years of age had, at the request of their parents, remained in treatment. The length of time that experimental subjects had been out of treatment ranged from O to 12 years (mean = 5), with the normal-functioning children having been out for 3 to 9 years (mean = 5).

The mean age of subjects in the control group was 10 years (range 6 to 14). The length of time that these children had been out of treatment ranged from 0 to 9 years (mean 3). Thus, experimental subjects tended to be older and had been out of treatment longer than had control subjects. This difference in age occurred because the first referrals for the study were all assigned to the experimental group due to the fact that referrals came slowly (7 in the first 3.5 years) and therapists were available to treat all of them. (As noted earlier, subjects were assigned to the experimental group if therapists were available to treat them; otherwise, they entered the control group.)

Statistical analyses were conducted to test whether a bias resulted from the tendency for the first referrals to 80 into the experimental group. For example, it is conceivable that the first referrals could have been higher functioning at intake or could have had a better prognosis than subsequent referrals, If so, the subject assignment procedure could have favored the experimental group. To assess this possibility, we correlated the order of referral with intake IQ and with IQ at the first follow-up (age 7 years). Pearson correlations were computed across both groups and within each group. These analyses indicated that the order in which subjects were referred was not associated with intake IQ or outcome IQ. Consequently, although the tendency for the first referrals to enter the experimental group created a potential bias, the data indicate that this was unlikely.


The assessment procedure included ascertaining school placement and administering three standardized tests. Information on school placement was obtained from subjects' parents, who classified them as being in either a regular or a special education class (e.g., a class for children with autism or mental retardation, language delays, multi-handicaps, or learning disabilities). The three standardized tests were as follows:

1. Intelligence test. The Wechsler Intelligence Scale for Children-Revised (Wechsler, 1974) was administered when subjects were able to provide verbal responses. This included all 9 best-outcome experimental subjects plus 8 of the remaining 10 experimental subjects and 6 of the 19 control subjects. For subjects who were not able to provide verbal responses, the Leiter International Performance Scale (Leiter, 1959 and the Peabody Picture Vocabulary Test-Revised (Dunn, 1981) were administered. All of these tests have been widely used for the assessment of intellectual functioning in children with autism (Short & Marcus, 1986).

2. The Vineland Adaptive Behavior Scales (Sparrow, Balla, & Cicchetti, 1984). The Vineland is a structured interview administered to parents assessing the extent to which their child exhibits behaviors that are needed to cope effectively with the everyday environment.

3. The Personality Inventory for Children (Wirt, Lachar, Klinedinst, & Seat, 1977), This measure is a 6OO-item true-false questionnaire filled out by parents that assesses the extent to which their children show various forms of psychological disturbance (e.g., anxiety, depression, hyperactivity, and psychotic behavior).

These three tests were intended to provide a comprehensive evaluation of intellectual, social, and emotional functioning. All of the tests have been standardized on average populations. Hence, they provide an objective basis for comparing subjects to children without handicaps across the various areas that they assess.

Data were obtained on all subjects except one girl in the control group, who was known to be institutionalized and functioning very poorly. The 9 best-outcome subjects (those who had been classified as normal functioning at age 7) received particularly extensive evaluations, as outlined later. Of the 28 remaining subjects, 17 were evaluated by staff members in our treatment program, and 11 received evaluations from outside agencies such as schools or psychology clinics. (In some cases, the outside agencies did not administer all of the measures in this battery.)

Evaluation of Best -Outcome Subjects. To ensure objectivity in the evaluation of the best-outcome subjects, we arranged for blind administration and scoring of all tests for these subjects as follows. A psychologist not associated with the study recruited advanced graduate students in clinical psychology to administer the tests. The examiners were not familiar with the history of the children, and the psychologist told them simply that the testing was part of a research study on assessment of children. The psychologist advised them that the nature of the study necessitated providing only certain standard background information: age, school placement and grade, and parent's name and phone number. To increase the heterogeneity of the sample and to control for any examiner bias, each examiner also tested one or more subjects who were matched in age to the experimental subjects and had no history of behavioral disturbance. The examiners were randomly assigned an approximately equal number of subjects for testing at the experimental group and the comparison group. Two experimental subjects were not living in the local area. Therefore, for each of them, the psychologist recruited a tester from the subject's hometown area as well as an age-matched control subject, and data were collected as just described. In addition, the child's examiner filled out a clinical rating scale following a structured interview that covered a list of standard topics, including friendships, family relations, and school and community activities. The interview was designed both for eliciting content and for sampling interpersonal style. The rating scale consisted of 22 items, each scored 0 (best clinical status) to 3 (marked deviance) points. The items were designed to include likely areas of difficulty for children with autism of average intelligence (e.g., compulsive or ritualistic behavior, empathy for and interest in others, a sense of humor) as well as areas of potential difficulty for the general child population (e.g., depressed mood, anxiety, hyperactivity). (The complete scale and a copy of instructions for the clinical interview can be obtained by writing to the third author).

Experimental Versus Control Group

This first section examines the overall effects of treatment through comparison of the follow-up data from the 13 subjects who received the intensive (experimental) treatment to the data from those who received the minimal (control) treatment. Data were obtained from all subjects on school placement and from all but one subject in the control group on IQ. On the Vineland, scores were obtained for 18 of 19 experimental subjects and 15 of 19 control subjects. The lowest availability of follow-up scores was on the Personality Inventory for Children, with scores for 15 experimental subjects and 12 control subjects.

The subjects in the control group who had Personality Inventory for Children scores did not appear to differ from subjects who were missing these scores, as compared on tests for differences in intake IQ, IQ at 7 years old, or IQ in the present study.

As noted earlier, 17 of the 28 subjects who were not in the best-outcome group were evaluated by Project staff members, 11 were evaluated by outside agencies, and 1 was not evaluated. To check whether Project staff members were biased in their evaluations or in their selection of which subjects to evaluate, we used i tests to compare subjects they evaluated to those evaluated by outside agencies on intake IQ, IQ at age 7 years, and TQ in the present study. No significant differences between subjects evaluated by Project staff members and those evaluated by outside agencies were found.

School Placement. In the experimental group, 1 of the 9 subjects from the best- outcome group who had attended a regular class at age 7 (J. L.) was now in a special education class. However, 1 of the other 10 subjects had gone from a special education class to a regular class and was enrolled in a junior college at the time of this follow-up. The remaining experimental subjects had not changed their classification. Overall, then, the proportion of experimental subjects in regular classes did not change from the age 7 evaluation (9 of 19, or 47%). In the control group, none of the 19 children were in a regular class, as had been true at the age 7 evaluation. The difference in classroom placement between the experimental group and the control group was statistically significant, X2 (1, N= 38)= 19.05, P<. 05.

Intellectual Functioning. The test scores for the experimental group and control group on intellectual functioning, adaptive and maladaptive behaviors, and personality functioning are summarized in Table 1. As can be seen in the table, the experimental group at follow-up had a significantly higher mean IQ than did the control group. This difference was significant, t(3~) = 2.97, P < .01. Eleven subjects CS8"/o) in the experimental group obtained full-scale IQs of at least 80; only 3 subjects ~17%) in the control group did as well. The scores were similar to those obtained by the experimental group and control group at age 7 (mean IQs of 83 and 52, respectively), indicating that the experimental group had maintained its gains in intellectual functioning between age 7 and the time of the current evaluation,

Adaptive and Maladaptive Behavior. On the Vineland, the mean overall or composite score was 2 in the experimental group and 48 in the control group. (The average score for the general population on this test is 100, with a standard deviation [SD] of 15.) On the three subscales--Communication, Daily Living, and Socialization-each score closely paralleled the Composite score. The interaction between the groups and the subscales was not significant, indicating that across the three subscales, the experimental group consistently scored higher than did the control group. As can be seen in Table 1, Maladaptive Behavior was significantly higher in the control group, t(31)= 2.33, P<.05. The mean score for the control group was in the clinically significant range whereas that of the experimental group was not. (Scores of ~3 and above are considered to be indicative of clinically significant levels of maladaptive behavior at ages 6 to 9 years; 12 or above, at 12 to 13 years; and 10 or above, at 14 years and older.) Thus, the findings indicate that the experimental group showed more adaptive behaviors and Fewer maladaptive behaviors than did the control group.

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