Near Infrared Spectroscopy Neurofeedback Training for ADHD

ADHD is one of the most frequently diagnosed conditions in childhood and at least half of patients have symptoms that persist into adulthood. It is important to seek effective treatments for ADHD because children with ADHD often do not reach their full potential and are at increased risk of other psychiatric difficulties in childhood, adolescence and adulthood, including disorders of mood, anxiety, conduct and substance misuse.

Increasingly the available evidence suggest that ADHD may be the result of abnormal levels of certain chemicals and altered brain function. Standard treatment with stimulant medications are aimed at the chemical imbalance and whilst they may help some children, they are of limited benefit in others and of no benefit in more than a quarter of children. Parents are often reluctant to consider medication due to concerns over side effects and the unknown longer term effects of these drugs on their children's developing brains and bodies. Non- drug treatments can provide an alternative and/or adjunct that may overcome some of the concerns about the long-term side effects of drugs. Furthermore, the latest guidelines from the National Institute of Clinical Excellence (NICE, 2008) recommend that medication should only be used as a first-line treatment in severe cases of ADHD. In all other cases it is advised that children receive a group treatment programme and that parents or carers receive parent training and education on ADHD. Whilst these guidelines have been welcomed for promoting alternatives to medication for treating ADHD,concerns have been raised about the feasibility and efficacy of the recommended group interventions for children and individual treatments may be easier to implement and more effective for these children. Therefore, although there are a number of treatments for ADHD, they have limitations in terms of efficacy, tolerability, side effects and practicability. There is therefore a clear rational to investigate new treatments that may be superior in efficacy or valuable as additional or alternative treatments.

Several individual, non-drug interventions for ADHD have emerged over the last thirty years. These include at home parental guidance, classroom based teacher intervention, behavioural therapy, herbal treatment and nutritional supplements. Neurofeedback training appears one of the most promising because the technique directly targets brain functioning in key areas. Neurofeedback training (NTx) uses signals directly from the brain to make subjects aware of brain function. It is an established treatment in epilepsy, migraine and stroke rehabilitation. Abnormal brain function (electrical and blood flow) has been consistently demonstrated in ADHD and may therefore be targeted with neurofeedback. These findings have formed the basis for considering NTx as a potential alternative to medication in the treatment of ADHD.

Compelling evidence from recent controlled studies indicate that NTx that uses electric brain signals (EEG) is a useful treatment in ADHD and that the effects last for at least 6 months. Near infrared spectroscopy neurofeedback (NIRS) neurofeedback training (NIRS NTx) is a newer alternative to EEG NTx. It is easier to administer and may require fewer treatment sessions. NIRS can determine changes in brain activity by measuring changes in the amount of oxygen in the brain. Rather than requiring subjects to alter the pattern of electrical brain activity, NIRSNTx trains subjects to alter blood flow in specific brain areas. Abnormal brain blood flow has been demonstrated in ADHD and typically, these abnormalities include reduced activity of brain areas just behind the forehead.

NIRS NTx is a low cost technique and it can be applied at home, clinic or school. NIRS can safely be applied to the head because the low energy light used for the technique do not cause damage to underlying tissues and is less than 5% of the exposure that occurs in ordinary midday sunlight.

NIRSNTx is performed using a laptop computer, spectroscope, sensor headband and headphones. Typically, patients watch a film on the computer screen whilst wearing the sensor headband and headphones. The headband applies two light sources (red and infrared) and a sensor to the skin overlying the brain area of interest. No special preparation of the skin is necessary. The lights shine through the skin and skull into the brain, where it is absorbed in different quantities depending on the amount of oxygen carried in the blood. Some of the light that is not absorbed is reflected back to the sensor. This signal is analysed in the spectroscope and data are sent to the computer where it is interpreted by software that generates the feedback. Increased blood flow results in positive reinforcement (the film clip advances) and reduced blood flow results in negative reinforcement (the film clip stops and a monotone auditory signal is heard). Subjects learn how to spontaneously increase blood flow to the brain region of interest to enjoy uninterrupted viewing of the film clips. Consequently, NIRS can provide realtime biofeedback to subjects regarding blood flow in specific brain areas.

A typical session of NIRS NTx involves 10 minutes of training at two brain sites. In view of known haemodynamic changes in ADHD and the functional neuroanatomy of attentional control, these sites would be the right and left prefrontal areas. Treatment sessions are offered once or twice weekly for between 15 and 48 sessions. There are no published tolerability data, and available reports come from personal communications with clinicians. The only side effect reported is mild headache that is short lived and self-limiting, immediately after training or on the day following, in around 10% of patients. Clinical observations suggest this predicts a good response to NTx.

Neurofeedback treatment mechanism The human brain has a lifelong capacity to adapt to changes by reorganising itself. This ability is called plasticity and partly works through changes in bloodflow. Examples of plasticity in adults include finding that brain activation leads to brain growth, rewiring of neurons following stroke, larger brain areas dedicated to moving the fingers of musicians, and enlargement of certain brain areas in London cab drivers. NIRSNTx may act in part by enhancing the brain's capacity for plasticity.

In summary, available evidence suggests that NIRS NTx appears safe and capable of targeting specific brain areas that show reduced activity in ADHD.