Abstract

Literature Review

In the nineties, various treatment methods have been proposed for Attention Deficit Hyperactivity Disorder (ADHD). One such treatment is Electroencephalographic (EEG) neurofeedback. This article reviews much of the research to date on the application of EEG neurofeedback in the treatment of ADHD. Most commonly used assessment tools, protocols, and electrode placement for conducting neurofeedback research as well as clinical applications for ADHD are explored. In addition, basic terms necessary for the understanding of ADHD and neurofeedback are discussed. Lastly, directions for future research are proposed.

In the early 1970s, researchers first proposed several theories and protocols for using neurofeedback as an assessment and treatment approach for children with ADHD. In 1973, Satterfield, Lesser, Saul and Cantwell proposed a "low-arousal" hypothesis for hyperkinetic children. He found that under-arousal corresponded to decreased amplitudes in high frequency EEG (beta). Seifert & Lubar (1975) published the first article demonstrating a reduction in seizure activity by using neurofeedback training. Lubar & Bahler (1976) published a series of case studies showing the effectiveness of sensorimotor rhythm (SMR) training in reducing seizures (replicating Sterman's 1973 findings). This study found that these seizure patients also experienced increased attentiveness in school. These findings prompted another case study by Lubar and Shouse (1976) to determine the effectiveness of neurofeedback training using SMR to help children with ADHD. This blind crossover study provided the first clear evidence that neurofeedback training, utilizing SMR with theta inhibition, was an effective intervention for working with an ADHD child.

In 1976, Lubar began treating ADHD children using neurofeedback. He noticed that those children with ADHD, with or without hyperactivity, demonstrated a difference in specific types of brain waves. For example, the "beta" brain wave was found to be significantly lower in amplitude and duration compared to "theta" activity, which was higher in amplitude. More specifically, he found those children with attentional and reading difficulties, but not with hyperactivity problems, produced excessive theta activity and deficit beta production. In 1985, Lubar, Bianchini, Calhoun, & Lambert provided a strong rationale involving theta suppression for ADHD children. More extensive studies were published following this study, confirming the relationship between slow wave patterns and ADHD, and providing evidence for the effectiveness of neurofeedback training for ADHD children (e.g., Janzen, Graap, Stephanson, Marshall, & Fitzsimmons, 1995; Linden, Habib, & Radojevic, 1996; Lubar, 1991; Lubar & Lubar, 1984; Lubar & Shouse, 1997; Shouse and Lubar, 1979; Lubar, Swartwood; Swartwood, & O'Donnell, 1995; Lubar, Swartwood, Swartwood, and Timmerman, 1995; Othmer, Kraiser, & Othmer, 1995; Tansey & Bruner, 1983; Tansey, 1984, 1985, 1990). Moreover, recent studies have provided evidence of a relationship between the ability to change EEG and improve attention (Lubar, Swartwood, Swartwood & O'Donnell, 1995; Lubar, Swartwood, Swartwood & Timmerman, 1995).

After several years of research, Lubar et al. (1995) have concluded that for children, under the age of 14, the reduction in theta activity seems to be the key component correlated with reduction of ADHD symptoms. These authors suggest that there is a maturational lag that is reflected in the persistence of excessive theta activity for ADHD subjects when compared to age-matched norms. In addition, Mann et. al., (1992) have supported these findings, concluding that the distribution of EEG frequency for ADHD boys correspond to those of more immature brain activity, exhibited by younger children. For adults, the findings have shown that increasing the amplitude and duration of beta brain wave activity seems to be of primary importance.

From 1986 to 1991, topographic brain mapping studies further clarified the difference in EEG's between ADHD and matched controls. In 1992, Mann, Lubar & Zimmerman, Miller, and Muenchen found that theta activity was obtained in various locations of the brain (e.g., frontal and central) and decreased beta activity was found in frontal and temporal locations. These findings demonstrated that ADHD (with hyperactivity) formed a neurologically distinct group from controls.

Other assessment modalities have also found differences between ADHD and control subjects. Positron Emission Tomography (PET) data indicated decreased glucose metabolism in areas of the brain involved in motor activity and attention in ADHD (hyperactive) versus normal controls (cited in Lubar seminar at the A.A.P.B. fall workshop 1996; Zametkin et al., 1990). Later, Sieg, Gaffney, and Preston (1995) used Single Photon Emission Computed Tomography (SPECT) to explore the brain imaging of ADHD children. These researchers demonstrated that ADHD children exhibit a maturational delay in brain regions associated with attention. These findings are supported by EEG research which also found that the comparison between the brain mapping of ADHD and non-ADHD boys revealed increased theta production and decreased beta production in ADHD boys (Mann, et al., 1992).

Rossiter and LaVaque (1995) compared the effectiveness of neurofeedback to stimulant medication in reducing ADHD symptoms. The neurofeedback subjects exhibited improvements in Test of Variable Attention (TOVA) scores that were comparable to the control group receiving medication. The results indicated that neurofeedback is a viable alternative to the use of stimulant medication. Neurofeedback researchers have indicated that for many ADHD individuals the long-term benefits of neurofeedback outweigh the state-dependent learning effect of medication (Lubar, Swartwood; Swartwood, & O'Donnell, 1995; Lubar, Swartwood, Swartwood, and Timmerman, 1995; Rossiter and LaVaque, 1995).

This section includes key terms necessary in understanding the process and application of neurofeedback.

The DSM-IV criteria for classification of ADHD are grouped into inattention, hyperactivity, and impulsivity. Children, adolescents and adults with ADHD, with or without hyperactivity, have difficulty concentrating. They often underperform in school and at work even though they are quite bright. The primary characteristics of ADHD include inattention, impulsivity, and hyperactivity. What distinguishes ADHD children from others is the prevalence, and severity of these symptoms, in a wide range of situations and circumstances.

In recent years Topographic Brain-Mapping studies have been used to identify regions of the brain, which are associated with increased activity during specific states. Some researchers have classified bandwidths of electrical activity by names such as beta, theta, SMR, EMG, and alpha (see table 1). Classifying bandwidths allows researchers to relate different states to one or more of these bandwidths.

Sensors are attached to the scalp and ear using conductive paste. These sensors measure brain activity, which is then converted into frequencies and amplitudes produced by the brain. The computer then converts this information into visual and auditory feedback. Through this feedback, the person can begin to experience how their brain is reacting during different situations, and learn how to change their brain wave patterns. By continuously practicing neurofeedback techniques, the individual learns to change and control their brain patterns. During neurofeedback training, ADHD individuals are taught to increase their fast wave activity (e.g., beta and SMR) and decrease their slow wave activity (e.g., theta).

These assessment tools have been utilized by various studies in ADHD research:

• WISC -R and III / WAIS-R or Kaufman Brief Intelligent Test
• TOVA- computerized continuous performance test
• Parent and teacher reports (most often used Connors or shorter variation)
• DSM -3R or IV criteria modified into Parent, teacher Questionnaire - SNAP
• WRAT-R

Some researchers use "Scull Caps" to collect data. This device is similar to a swimming cap. The cap, which contains 19 electrodes, fits over an individual's head. Each electrode is placed upon one cite identified in Figure 1. Research has shown that certain areas of the brain exhibit more activity associated with attention (see Table 2). Some researchers use a "bi-polar" placement. This method involves placing two electrodes over specific sites (brain regions). Others use "mono-polar" placement, which involves using one electrode over one brain region and one electrode attached to the ear. Both have been shown to be efficient methods of conducting neurofeedback.

Table 2

Source: Fifth annual winter conference on Brain Function-EEG, modification and training; advanced meeting colloquium, (Palm Springs February 1997)

Table 4

Despite only a few decades of scientific research, neurofeedback is quickly growing into a mature science. In particular, the application of neurofeedback has become recognized as a valuable tool in the treatment of ADHD. This growth has been aided by factors such as advancement of technology and better understanding of ADHD. However, since most early studies that examined the efficacy of neurofeedback as a treatment for ADHD were composed of small sample sizes, conclusions are difficult extrapolate. Hence, future research must utilize even greater sample sizes and employ more standardized methodology. In addition, subject selection should also be more rigorous. The use of appropriate control groups and the recruitment of pure ADHD without comorbidity of other disorders are necessary. Moreover, when selecting subjects, maturational shifts should be taken into account. Furthermore, methodological differences should be drawn between pure neurofeedback versus neurofeedback and academic training. Lastly, long term follow-up studies are necessary to track the efficacy of neurofeedback.