Neurofeedback, the use of feedback using features of EEG
activity, to change the brain’s state, has been around since the 1970s. It
holds unique appeals and challenges for clinicians, researchers, and the public
and has been particularly popular as a complementary treatment for ADHD. In a
typical neurofeedback session, you sit facing a computer or video screen with
1-4 EEG electrodes affixed to your head playing a video game with your mind.
Depending on the software and goals, you might be instructed to levitate CGI
rocks on a screen or keep a video-game character running around obstacles using
your mind. The success depends on whether or not you reach or exceed a target
level of a frequency range, or a particular ratio of frequencies in the EEG.
Does this kind of neurofeedback work? While some studies
show that it does, in some sense, to some degree, recent meta-analyses and
placebo-controlled studies strongly suggest that it “does not.” But, to regard
the situation in terms of such a dichotomy may obscure what these studies imply
not only about neurofeedback for ADHD, but also about the nature of ADHD, the
relations between EEG and cognition, and the processes of conditioning and
learning. The question of neurofeedback’s value is a significant one, and the
seeming contradiction among studies raises implications and questions, possibly
paradigm-shaking, for theory and practice in both neuroscience and
complementary medicine…
The first work relevant to ADHD was the use of SMR
conditioning as an anti-convulsant, first in cats, then humans (Tan et al. 2009
in Arns et al. 2014). SMR, the “sensory-motor-rhythm” (also called mu waves in
humans) are spindles at 13-15 Hz (in the beta range) that occur in the
sensorimotor cortex, most prominently in the absence of movement. (It was Barry
Sterman who then famously discovered, by accident, that cats who had gone
through SMR conditioning were less likely to have seizures when dosed with hydrazine,
a component of rocket fuel (a NASA study); it was confirmed that SMR therapy
could reduce seizures in human epilepsy, and that became one of the early
successes of neurofeedback). Studies in the 70s first showed that training
children to control SMR decreased hyperactivity and distractability. The
cat-SMR studies suggested that SMR training increased density of sleep-spindles
and depth of sleep–hinting that, in some people, ADHD may be related to sleep deprivation. SMR /
beta-increase is still among the most popular and well supported treatment
protocols for ADHD.
70s research also first showed that the apparent meanings of
recognized EEG frequencies were insufficient for therapeutic purposes; for
example, increasing alpha-waves, , supposedly the frequency of calm, had no
benefit for hyperactivity.
Around the same time, a second ADHD-relevant signal was
discovered—the Contingent Negative Variation or CNV. CNV is not a matter of frequency, but rather
a a kind of Slow Cortical Potential (SCP) a relatively slow (e.g. 300
millisecond) and subtle negative shift in the of the EEG from some cortical
area which seems to show anticipation of an action or stimulus. A negative correlation was discovered between
the amount of CNV and the severity of ADHD symptoms and the potential to
increase CNV or SCP through neurofeedback gained support. Subjects are trained
to shift the SCP negatively (for attention) or positively (for relaxation), and
this is a common protocol for ADHD therapy today.
Another group at UCLA (Abney, et al.) collected a database
of EEG from ‘normal, healthy’ people and used early computers to average and
compare to groups of people diagnosed with ADHD, thereby deriving the idea of
the theta-beta ratio (TBR), the ratio between the fraction of EEG activity in
the theta frequency to the fraction of activity in the beta range, as both a
diagnostic and target for ADHD neurofeedback.
The TBR is the first FDA approved EEG based diagnostic test for ADHD and
is also a popular EEG neurofeedback metric.
Conclusions regarding the efficacy of neurofeedback for ADHD
are based most importantly on subjects’ behavior outside of treatment sessions,
often as rated by teachers, and/or parents. Some studies have had blind raters,
others not; in many studies the degree of blindness can only be inferred. Some
research uses tools to test more specific dimensions of cognitive performance,
but conclusions focus on the three definitive symptoms of ADHD–distractability,
impulsivity, and hyperactivity—which are normally rated, rather than tested.
And of course, the subjects’ performance during the neurofeedback process is a
crucial dimension of the research but also does not substantiate efficacy as a
medical treatment.
Studies in the 90s and 2000s, and a 2009 meta-analysis (Arns
et al), seemed to confirm that both TBR and SCP therapy can bring significant
improvements in attention and impulsivity, and more long-lasting effects than
medication. Some studies seemed to show an advantage for SCP over TBR in
relation to hyperactivity, but this still needs confirmation.
However in 2012-2013 placebo-controlled studies were
published showing no significant difference between real and sham neurofeedback
(where the subject’s EEG is not generating the feedback)(e.g. Arnold et al.
2012). Further meta-analyses in 2013 and 2014 looked at “blindness” in the
studies and seemed to show that ADHD neurofeedback only has a significant
effect only if non-blind parents and teachers, rather than blind raters,
evaluate the behavioral improvements.
Yet clinicians often swear by it as do some patients.
Together, the research on ADHD neurofeedback seems to
suggest that neurofeedback for ADHD can work, but likely not in the straightforward
manner previously assumed; its effects may be to a large degree unrelated to
the EEG aspect of the treatments! Or they may be pointing us towards new
understandings of the relations between EEG and cognition. Here are some
specific questions regarding . . .
ADHD: Are there sub-types of ADHD with different causes and
neural profiles? Evidence hints that some may be related to sleep-derivation,
others hyperarousal.
EEG: What causes differences in TBR and SMR aside from ADHD?
Is a standard average TBR a good diagnostic, or does it mask the importance of
individual variation? Evidence suggests that theta-rhythms might play a crucial
role in executive control, so are TBR protocols, which involve theta-reduction,
sabotaging their own goals, reducing the value of beta-increase for ADHD?
Neurofeedback: How important is learning theory to the
efficacy of neurofeedback? How important are specific types of feedback? How
much is our lack of standard treatment protocols clouding study results? How
important is parenting style or other “non-specific” factors that might explain
how neurofeedback can work other than through its presumed mechanism?
These questions have been the targets of relatively little
or no research. But the fact that we are asking them shows that we have learned
much and the next few years will surely uncover more puzzle-pieces with further
glimpses of the emerging picture.
http://sapienlabs.co/neurofeedback-and-adhd/
References at link.
Cortese S, Ferrin M, Brandeis D, Holtmann M, Aggensteiner P, Daley D, Santosh P, Simonoff E, Stevenson J, Stringaris A, Sonuga-Barke EJ; European ADHD Guidelines Group (EAGG). Neurofeedback for Attention-Deficit/Hyperactivity Disorder: Meta-Analysis of Clinical and Neuropsychological Outcomes From Randomized Controlled Trials. J Am Acad Child Adolesc Psychiatry. 2016 Jun;55(6):444-55.
ReplyDeleteAbstract
OBJECTIVE:
We performed meta-analyses of randomized controlled trials to examine the effects of neurofeedback on attention-deficit/hyperactivity disorder (ADHD) symptoms and neuropsychological deficits in children and adolescents with ADHD.
METHOD:
We searched PubMed, Ovid, Web of Science, ERIC, and CINAHAL through August 30, 2015. Random-effects models were employed. Studies were evaluated with the Cochrane Risk of Bias tool.
RESULTS:
We included 13 trials (520 participants with ADHD). Significant effects were found on ADHD symptoms rated by assessors most proximal to the treatment setting, that is, the least blinded outcome measure (standardized mean difference [SMD]: ADHD total symptoms = 0.35, 95% CI = 0.11-0.59; inattention = 0.36, 95% CI = 0.09-0.63; hyperactivity/impulsivity = 0.26, 95% CI = 0.08-0.43). Effects were not significant when probably blinded ratings were the outcome or in trials with active/sham controls. Results were similar when only frequency band training trials, the most common neurofeedback approach, were analyzed separately. Effects on laboratory measures of inhibition (SMD = 0.30, 95% CI = -0.10 to 0.70) and attention (SMD = 0.13, 95% CI = -0.09 to 0.36) were not significant. Only 4 studies directly assessed whether learning occurred after neurofeedback training. The risk of bias was unclear for many Cochrane Risk of Bias domains in most studies.
CONCLUSION:
Evidence from well-controlled trials with probably blinded outcomes currently fails to support neurofeedback as an effective treatment for ADHD. Future efforts should focus on implementing standard neurofeedback protocols, ensuring learning, and optimizing clinically relevant transfer.