What is neuromodulation + why is it used?
Neuromodulation is the name given to different medical procedures that can change the activity happening in the brain through directly stimulating it in a number of ways.
The aim of neuromodulation is to help improve symptoms of mental illness (such as depression) by changing how some areas in the brain are working.
How can mental health conditions have an impact on the activity in the brain?
Brain scans show that some people with mental health conditions have different levels of activity in parts of their brain. This depends on which mental health condition someone has. In some conditions brain activity might be greater while in others it might be less.
Depression - parts of their brain might be less active. Psychosis (e.g. schizophrenia) - parts of their brain might be more active.
How can I get neuromodulation?
Neuromodulation is not available in all NHS mental health services at this time.
Speak to your mental health team about whether this treatment might be available at your service, and whether it would be suitable for you.
Types of neuromodulation
The most common methods for performing neuromodulation are:
Placing a magnetic coil against the head (rTMS)
placing electrodes against the head and passing a small current between them (tDCS) - both methods can change the activity of brain cells (neurons), and how they connect with other parts of the brain.
Two other types of neuromodulation, TNS and VNS, are not used as often. They involve stimulating a nerve outside of the brain, which sends signals back to the brain to change how it functions.
How effective is neuromodulation?
Depends on technique and condition
Quite new, limited research
Best evidence is for rTMS - most researched, shown to be effective in many people
Difficult to create placebo for trials (people can tell the difference between real tx and placebo)
Difference in opinion as to where, how to find the right place, length of session, number of sessions
What is Repetitive transcranial magnetic stimulation (rTMS)?
First developed in 1980s
Magnetic coil held next to the head is turned on and off - changes magnetic field - affects neurons directly underneath (can be placed on diff areas)
Turn on and off quickly: excite the neurons (more active), slowly: inhibit (less active)
How long does rTMS last?
Effects of this treatment last after it has been performed, though this can vary between individuals, more research needed to find out more about why this is.
? change the longer-term connections between brain cells, helping them to form new connections with each other
What conditions is rTMS used to treat?
Mostly depression - prefrontal cortex (less active in depression)
Hearing voices - tempoparietal junction (more active in people hearing voices)
OCD, anxiety disorders, eating disorders, MCI, depersonalisation disorders, PTSD, stopping smoking, pain conditions
What happens when I have rTMS?
First session - clinician will try to find the best place to apply the magnetic field over your brain + try to find out how strong the magnetic field needs to be to stimulate your brain. (varies depending on things like hair and bone thickness). (initial tests of the treatment over the top of your head to make the muscles in your hand twitch, normally takes a few minutes, painless)
Usually daily for 3-6 weeks, session usually lasting between 3 minutes and a little over half an hour (depending on the way the treatment is given, the machine, the speed the magnetic coil is set to turn on and off). Some methods use regular pulses, and some have short but rapid pulses with gaps in between.
Newer method called ‘intermittent theta-burst stimulation’ (iTBS): shorter treatments of 3-5 minutes. Not shown to be any more / less effective than standard rTMS.
Can be either side of the head, some treatments being performed on both sides. ‘booster’ rTMS if your symptoms return / ‘maintenance’ rTMS after recovering. Less frequent. At this time, there are not well-established guidelines for when this should occur.
rTMS side effects
Awake during treatment, not usually painful, ‘tapping’, can cause muscles to twitch
Temporary headaches, no evidence of longer term issues e.g. memory
Can affect medical devices (cochlear implants, cardiac pacemakers, metal in head). Might not be suitable for epilepsy or TBI. Caution - weigh up pros and cons.
Transcranial direct current stimulation (tDCS)
More recent treatment than rTMS.
2 small metal discs (electrodes) are placed on the head and a weak current of 1 or 2 milliamps (mA) is passed between them by a battery - changes the firing pattern of neurons (different way to rTMS). Neurons that sit between the two electrodes are most affected. As with rTMS, the effects of tDCS seem to last after the treatment has been performed.
What conditions is tDCS used to treat?
Most studied in treating depression
May also help: hallucinations, cognitive difficulties in psychosis, OCD, substance misuse
Evidence for tDCS
Mainly been used in research, some evidence suggest effective in depression, may vary between individuals and severity
Should only be used in special arrangements for clinical governance. Local trust will need to decide whether it might be used to help a patient.
tDCS side effects
Most people don’t experience pain, usually no SE
SE reported: redness or burning sensation where applied, skin sensitivity, itching, tingling, headaches, light-headedness, blurred vision, sleepiness
Some reports of mania (in people who have BPAD), usually resolves when tDCS stopped
What happens when I have tDCS?
2 small metal discs (electrodes) applied to head (head band is often used to help keep them in place). Attached by wires to a small device that controls the level of the small electrical current passing between the metal discs.
Usually given daily for several weeks, then a few times a week for several more weeks. Awake throughout the session, each session usually lasts between 20-30 mins.
Trigeminal nerve stimulation (TNS)
Involves applying an electrode to the forehead and passing a small current through it. This treatment tries to stimulate the trigeminal nerve that detects touch and sensation on the face.
What conditions is TNS used to treat?
TNS has been used to treat severe depression that has not responded to other treatments.
Some evidence for ADHD
What evidence is there for TNS?
Evidence for TNS in depression: very limited. Currently no guidelines available from NICE.
Some evidence for using TNS to treat ADHD.
What happens when I have TNS?
Very similar to that for tDCS. However, in most research trials TNS has only been given for up to two weeks.
TNS side effects
TNS has been studied less than tDCS, but the side-effects seem to be similar.
Vagus nerve stimulation (VNS)
Stimulates the body’s vagus nerve, which connects the brain to the rest of the body.
2 types:
Transcutaneous VNS (tVNS) – the vagus nerve is stimulated by holding a device against the neck.
Implanted VNS – where someone has an operation to insert a battery and a stimulator under the skin of the chest wall, wire leads from this to the vagus nerve in the neck.
First used to treat epilepsy in the 1990s. Some patients and clinicians noticed that it also improved the symptoms of some people with depression. VNS is currently offered in a small number of centres in the UK for people who have depression that has not been helped by other treatments.
What conditions is VNS used to treat?
Severe depression that has not responded to other treatments.
What evidence is there for VNS?
Growing positive research supporting use of implanted VNS for people with longstanding depression. Very little evidence to support the use of tVNS.
No major safety concerns when given for epilepsy. However, they have said that evidence for how effective VNS is in treating depression “is limited in quality”. Therefore, should only be used after very careful consideration about the potential benefits and risks.
Due to the nature of VNS, it is hard to ‘blind’ participants in trials - one reason why it can be difficult to work out how effective it is.
What happens when I have VNS?
VNS: surgical operation: under GA or under local anaesthetic. Two items are implanted under your skin near your collar bone. These are: a battery and stimulator (about the size of a watch and is a bit like a pace maker), a wire (placed under the skin, leads from the stimulator to the vagus nerve in the neck)
The battery and stimulator send electrical pulses through the wire to the vagus nerve.
Stimulator is always on, but it will usually stimulate the vagus nerve for 30 seconds every 5 minutes. Settings can be adjusted by a doctor using an external hand-held device. Will depend on you and how you respond to the treatment.
Intended to be a long-term treatment, battery lasts for ~ 7-10 years, depending on the settings used.
