Introduction

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by inattention and/or hyperactivity-impulsivity. Approximately 5 to 7% of all children meet criteria for ADHD. Due to inattentive and disruptive behavior in class, children with ADHD are at risk of academic difficulties, including underachievement, retaining grade, special educational placement, and suspension or drop-out from school. As ADHD related behaviors may disturb the learning process of classmates and may elicit maladaptive behav-
ior of both classmates and teacher, overall classroom functioning may decrease, both academically and socially.

Teachers play an important role in considering interventions. They may be confronted daily with children with ADHD and they need to have the ability to manage these children. Providing teachers with effective tools may benefit children with ADHD as well as their classmates, but moreover, may improve confidence and wellbeing of teachers themselves. As the most common treatment for children with ADHD is stimulant medication, which is limited by several factors (e.g. side effects, compliance problems), there is a need for non-pharmacological interventions, including school-based interventions. 

Previous studies on the effectiveness of school-based interventions show inconsistent results. 

The present study

The present study provides a meta-analytic review of published studies on classroom interventions for ADHD covering a period of 33 years of research. It aims to first, determine the effectiveness of several types of classroom interventions (antecedent-based, con-sequence-based, self-regulation, combined) that can be applied by teachers in order to decrease off-task and disruptive classroom behavior in children with symptoms of ADHD, second, to identify potential moderators (classroom setting, type of measure, students’ age, gender, intelligence, and medication use) and third, to qualitatively explore the direct or indirect affect of the classroom interventions on behavioral and academic outcomes of classmates.

Method

The guidelines for Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) were followed.

Inclusion and exclusion criteria

For the review, the studies needed to meet the following inclusion criteria:

1. written in english
2. participants attended grade 1-12 and had ADHD/ADD difficulties and an IQ of 70 or above
3. intervention had to be implemented by the teacher in the classroom and required no prental involvement
4. the interventions could be classified into one or more out of these categories:

   1. Antecedent-based intervention: An intervention that manipulates antecedent conditions, such as the environment, task, or instruction (e.g., seating, music, tutoring, choice making, computer-assisted instruction)

   2. Consequence-based intervention: An intervention that uses reinforcement and punishment to alter the frequency of target behavior (e.g., praise, reprimands, prizes, privileges, response-cost)

   3. Self-regulation intervention: An intervention aimed at the development of self-control and problem-solving skills to regulate cognition and behavior (e.g., self-instruction, self-monitoring, self-reinforcement)

5. The outcome measures were either teacher ratings or direct observations of off-task behavior (e.g., not attending to task or teacher, looking around), disruptive behavior (e.g., disturbing classmates, playing with objects, out of seat), and ADHD behavior (e.g., teacher rating on an ADHD rating scale) in the classroom.

6. The study could be classified into one of the following categories of experimental design categories:

   1. Between-subjects group design: A design that uses an intervention group and a non-intervention control group.

   2. Within-subjects group design (WSD): A design that applies the same intervention on each participant and assesses outcomes on at least two occasions.

   3. Single-subject design (SSD): A design that documents changes in behavior for an individual participant during intervention phases and non-intervention control phases.

7. Sufficient data were provided to compute effect sizes.

Search procedure

It was systematically searched for literature through online databases and manuals.

Coding procedure and moderating variables

Each study meeting inclusion criteria was systematically coded on several variables by the first
author. Variables that were examined as potential moderators included intervention type, classroom setting, type of measure, and characteristics of participants receiving the intervention, including age, gender, intelligence, and medication use. The categories antecedent-based, consequence-based, self-regulation, and combined were used to classify intervention type. The following codes were used:

Classroom setting - general education or other

Type of measure: teacher ratings, direct observations, or both

Participants: children or adolescents, gender, IQ

It is looked at the study quality (high quality, acceptable quality, unacceptable quality) and secondary quality indicators (evidence or no evidence). 

Statistical analyses

SPSS is used for the statistical analyses. Separate meta-analyses were performed on standardized mean differences (SMDs) for 24 within-subjects design (WSD) and 76 single-subject design (SSD) studies.

Results

A total of 4,553 records were identified through electronic databases and an additional 230 records were identified by the manual searches. A total of 89 articles meeting inclusion criteria were considered in the present meta-analytic review, yielding to 100 studies. 

Study characteristics

Different study characteristics are summarized in the article. These are year of publication, experimental design, examination classmates (yes or no), type of measure, intervention type, classroom setting, number of participants, age, a differentiation between children and adolescents, gender, IQ, medication use, and study quality. (see table in the article for more details)

The majority of WSD (within-subject design) studies (83%) obtained a weak rating of study quality and half of the SSD (single-subject design) studies (54%) had an adequate study quality and 43% were rated as weak.

Within-subject design studies

Effect sizes for WSD studies ranged from −0.08 to 3.00 (Winsorized value) with a median of 0.92. The mean weighted effect size was 0.92 and reached significance (95% CI [0.59, 1.25]).

Single-subject design studies

Effect sizes for SSD studies ranged from 0.42 to 7.00 (Winsorized value) with a median of 2.63. The mean weighted effect size was 3.08.

Direct effects on classmates

For all four WSD studies applying antecedent-based interventions, effect sizes for behavioral outcomes of classmates were positive, ranging from 0.21 to 1.97. Positive effects on classmates were also found for all four SSD studies.

Indirect effects on classmates

Positive indirect effects on behavioral outcomes of classmates were found for two out of three studies.

Discussion

Regarding the first aim of this study: The results indicate that classroom interventions reduce off-task and disruptive classroom behavior in children with symptoms of ADHD, which is in accordance with previous meta-analyses. It is indicated that interventions implemented in general education classrooms lead to a larger reduction in off-task and disruptive classroom behavior in children with symptoms of ADHD than interventions implemented in other classroom settings. 

Regarding the second aim of this study: no reliable conclusions can be drawn about potential moderators.

Regarding the third aim of this study: Results imply that classroom interventions for children with symptoms of ADHD have both direct effects on classmates, i.e., improvement of classmates’ behavior because they also benefit from the intervention, and indirect effects on classmates, i.e., profit from less classroom disturbance by children with symptoms of ADHD.

In summary:

Results showed that classroom interventions reduce off-task and disruptive classroom behavior in children with symptoms of ADHD. No reliable conclusions could be formulated about moderating effects of type of measure and students’ age, gender, intelligence, and medication use, mainly because of power problems. Finally, classroom interventions appeared to also benefit classmates’ behavioral and academic outcomes.

Limitations

First, the meta-analytic review was restricted to studies published in academic journals. Second, there was a trend for the smaller studies to show larger treatment effects than the larger studies. Third, most studies employed SSDs, for which exact expressions of effect size variances have not been derived. Fourth, potential moderators had to be analyzed using subgroup analyses instead of meta-regression analysis because the data were not normally distributed and therefore violated the assumptions for regression analysis. Finally, the results are most representative for boys in the age of 6 to 11 years, as only a minority of studies reported about samples including females and/or adolescents.

Future Research

First, girls should be more included in research onthis field, second, additional factors influencing the effectiveness of classroom interventions for children with symptoms of ADHD should be further examined, and finally, there is a need for higher quality studies in this field.

Implications for practice

As this review shows that teachers can effectively implement classroom interventions to reduce off-task and disruptive classroom behavior in children with symptoms of ADHD, it is important that classroom man-
agement training is offered to teachers.

Conclusion

This review indicates that classroom interventions reduce off-task and disruptive classroom behavior in children with symptoms of ADHD. WSD studies showed that consequence-based interventions are more effective than antecedent-based, self-regulation, and combined interventions. However, SSD studies showed largest effects for self-regulation interventions. Larger effects were obtained for children with symptoms of ADHD in general education classrooms than for those in other classroom settings. No reliable conclusions can be formulated about moderating effects of type of measure, and student’s age, gender, intelligence, and medication use. Finally, the study also indicates positive direct and indirect effects of these classroom interventions on classmates’ behavioral and academic outcomes. The results of this study may be used for educating and training teachers in dealing with children with symptoms of ADHD.