Bipolar Disorder and TMS
Also known as manic-depressive disorder, bipolar disorder is brain disorder causing unexpected changes in the person’s mood, energy and functional skills.
Bipolar disorder may cause impairment in the relationships, business life or school performance of the individual, or even suicide. Affecting 2.6% of the adult population in America, this disorder has a prevalence of around 2-3% in other countries.
Brain Areas Active in Bipolar Disorder
Bipolar disorder impairs the patients’ ability to regulate her/his emotions to an extent where it negatively affects their lives. The studies carried out with patients showing manic symptoms indicated a subcortical limbic activity increased as a result of emotional stimulants. Increased neural activities were shown in amygdala, insula and limbic subcortical areas, which are the brain parts associated with emotions, during the implicit processing of the negative scenes and negative emotional facial expressions in the bipolar manic disorder patients when compared to healthy individuals. However, in the cortical-cognitive pathway structures (ventrolateral prefrontal cortex, dorsolateral prefrontal cortex, anterior cingulate cortex, precuneus), a decrease was observed in the neural activation. During the decision-making test, the bipolar mania patients had an increase in the dorsal anterior cingulate activity, while having a decrease in the activity of orbitofrontal cortex (OFC), an effective area in emotional and behavioral control.
Bipolar Disorder and rTMS
TMS in bipolar disorder interesting, though the data on its reliability and effectiveness are on an initial phase. In the studies, it is generally hypothesized that the stimulation of the left prefrontal cortex or the inhibition of the right prefrontal cortex would be effective in the treatment of bipolar depression. In a case report, two bipolar patients were subjected to rTMS by aiming the left prefrontal cortex. It was observed that rTMS is effective in treating the depression of the patients, yet at the same time, it was seen that the manic symptoms of the patients using citalopram are triggered (Sakkas, 2002). Garcia-Toro (2001) stated that a bipolar depression patient turned into acute mania during the administration of rTMS on the left prefrontal cortex.
In bipolar mania, however, it was learned that the decrease of cortical activitiy in the right hemisphere is associated with the increase of the left hemisphere activity. Therefore, the stimulation of the right prefrontal cortex with TMS might cause a therapeutic effect on mania.
Repetitive TMS (rTMS) was administered over the right dorsolateral prefrontal cortex on 41 bipolar mania patients for 10 days. It was shown that the TMS implemented at high frequencies (stimulant) is an effective method that can be administered in addition to pharmacological treatment.
Grisaru et al. (1998), however, showed that the stimulation of the right prefrontal cortex with rTMS has an antimanic effect. Dell’osso (2009) showed that the inhibiting TMS, which was implemented through the right prefrontal cortex for 3 weeks on 11 drug-resistant bipolar patients, cured the depressions of the patients and decreased the scores taken from the depression scales.
In another study carried out on 9 bipolar patients diagnosed with bipolar mania, it was shown that the stimulant TMS implemented on the right prefrontal cortex cured the mania symptoms (Michael, 2004).
The studies available in the literature, researching the effects of TMS on bipolar mania, have contradictory results. There are more robust evidences regarding the effectiveness of the studies carried out on bipolar depression. In order to prove the effectiveness of TMS on bipolar disorder, there must be an increase in the numbers of the studies having extensive numbers of samples and being carried out under control and with the double-blind method.