Transcranial Direct Current Stimulation (tDCS) as depression treatment: much promise, some DIY risks

—For peo­ple with severe depres­sion, incor­rect appli­ca­tion can wors­en their con­di­tion or cause mem­o­ry loss. Nathan O’Nions/Flickr, CC BY-NC

Around 350 mil­lion peo­ple world­wide have depres­sion. Anti­de­pres­sant med­ica­tions are often pre­scribed to treat the con­di­tion, along­side talk­ing ther­a­pies and lifestyle changes such as reg­u­lar exercise.

But a sub­stan­tial pro­por­tion of peo­ple either don’t respond to anti­de­pres­sants, or expe­ri­ence such sig­nif­i­cant side effects that they’d pre­fer not to take them.

In search of alter­na­tive solu­tions, researchers around the world, includ­ing our team, are inves­ti­gat­ing tran­scra­nial direct cur­rent stim­u­la­tion (tDCS) as an alter­na­tive treat­ment for depres­sion. But this isn’t some­thing you can safe­ly try at home.

Unlike elec­tro­con­vul­sive ther­a­py, tDCS uses very mild elec­tric cur­rent to stim­u­late the brain and has few side effects. The mechan­ics of tDCS are quite sim­ple, involv­ing a bat­tery, two leads and the elec­trodes through which the cur­rent is passed.

—Researchers are yet to ful­ly under­stand the effects of vary­ing stim­u­la­tion approach­es. Tinydevil/Shutterstock

The stim­u­la­tion works by chang­ing the activ­i­ty of nerve cells in the brain. In depres­sion, the left frontal areas of the brain are often less active than usu­al. tDCS stim­u­lates this area to restore brain activity.

We’re still eval­u­at­ing the effec­tive­ness of tDCS, but so far stud­ies have found that tDCS works bet­ter than a place­bo (or sim­u­lat­ed treat­ment) at reduc­ing symp­toms of depression.

When com­bined with the anti­de­pres­sant med­ica­tion ser­tra­line (mar­ket­ed as Zoloft in Aus­tralia), the com­bi­na­tion tDCS-drug ther­a­py works bet­ter than med­ica­tion or tDCS alone.

Research has found that among peo­ple with depres­sion, a course of tDCS can improve the brain’s “neu­ro­plas­tic­i­ty”, which is the brain’s abil­i­ty to learn and adapt to changes in the environment.

The ther­a­py has a good safe­ty pro­file – if admin­is­tered by clin­i­cians and researchers trained in stim­u­la­tion tech­nique and safe­ty. Our research team has admin­is­tered thou­sands of tDCS ses­sions with­out incident.

But this is not the case when tDCS is used in the “DIY” con­text, with DIY users try­ing to stim­u­late their own brains.

This phe­nom­e­non is often guid­ed by online forums and web­sites ded­i­cat­ed to DIY tDCS. Users com­ment on their own expe­ri­ence and share tips on how tDCS can be used to treat their own depres­sion. Peo­ple with no med­ical train­ing and lim­it­ed under­stand­ing of tDCS self-treat their depres­sion and advise oth­ers on treatment.

—Stronger is not nec­es­sar­i­ly bet­ter. Ian Ruotsala/Flickr, CC BY-NC-SA

So, what can go wrong?

The most obvi­ous con­cern is that poor tech­nique and improp­er elec­trode place­ment could cause skin burns.

What’s more con­cern­ing is the abil­i­ty for tDCS to pro­duce last­ing changes in brain func­tion­ing. Depend­ing on how tDCS is giv­en, these changes could be good or bad.

A DIY user could, for exam­ple, cause last­ing impair­ment to their think­ing and mem­o­ry. For peo­ple with severe depres­sion, incor­rect appli­ca­tion could wors­en their con­di­tion or induce a hypo­man­ic (man­ic) episode.

When it comes to med­ica­tions, it’s impor­tant to get the right dose and dos­ing sched­ule. That’s why this role falls to qual­i­fied clin­i­cians and researchers. The same goes for tDCS: cur­rent inten­si­ty, elec­trode size and posi­tion, and the dura­tion and fre­quen­cy of the stim­u­la­tion deter­mine the effects in the brain.

The rela­tion­ship between dos­ing, inten­si­ty and posi­tion is high­ly com­plex. This isn’t a sim­ple case of “the stronger the bet­ter”. Even researchers are yet to ful­ly under­stand the effects of vary­ing stim­u­la­tion approach­es and much more research is needed.

As with oth­er forms of treat­ment, TDCS is not suit­able for every­one. In clin­i­cal research tri­als, par­tic­i­pants are screened for suit­abil­i­ty to receive stim­u­la­tion and their like­li­hood of respond­ing to treat­ment. The stim­u­la­tion is care­ful­ly con­trolled and the par­tic­i­pants’ mood is care­ful­ly mon­i­tored dur­ing and after the course of treatment.

—A sub­stan­tial pro­por­tion of peo­ple don’t respond to anti­de­pres­sants, or expe­ri­ence sig­nif­i­cant side effects. Divine Harvester/Flickr, CC BY-NC-SA

tDCS rep­re­sents a promis­ing future, where sim­ple and cost-effec­tive treat­ment for depres­sion is pos­si­ble, with­out drugs. Researchers world­wide are con­tin­u­ing to study this exper­i­men­tal treat­ment, which may one day become a con­ven­tion­al treat­ment for depression.

The accep­tance and pop­u­lar­i­ty of tDCS among the gen­er­al com­mu­ni­ty is encour­ag­ing. But tDCS is still exper­i­men­tal and isn’t safe to admin­is­ter at home. DIY users are not trained in prop­er tech­nique nor are they trained to iden­ti­fy, pre­vent or deal with unex­pect­ed outcomes.

–  Ker­rie-Anne Ho, PhD is a can­di­date in non-inva­sive brain stim­u­la­tion at UNSW Aus­tralia, and Colleen Loo a Pro­fes­sor of Psy­chi­a­try at Uni­ver­si­ty of NSW, Syd­ney. This arti­cle was orig­i­nal­ly pub­lished at The Con­ver­sa­tion.

Learn more:

• Start-up Thync rais­es $13 mil­lion to mar­ket tran­scra­nial stim­u­la­tion via con­sumer wearable
• Good sur­vey of brain stim­u­la­tion meth­ods, val­ue and limitations
• Exec­u­tive Sum­mary: Info­graphic on the Dig­i­tal Brain Health Mar­ket 2012–2020