A majority of hallucinations found in people who have schizophrenia are auditory in nature. Schizophrenics may hear voices that do not exist in reality. They can sometimes make disparging commentary towards the person and can be very distressing. The amount of patients that hear auditory hallucinations are in the range of 50 to 70 percent of schizophrenics. For auditory hallucinations, the left temporoparietal cortex has been show to have increased activity. Transcranial magnetic stimulation has been used to reduce activity in that area of the brain. By selectively reducing activity here, scientists are able to reduce the amount of non real voices a person hears.Other types of hallucinations outside the range of auditory (visual, sensory) are much rarer. You can read an interesting case study about using transcranial magnetic stimulation to reduce coenesthetic hallucinations in a single patient here. The coensthetic hallucinations consisted of having a feeling of undergoing electric shocks and also a feeling of having alien objects moving inside the person's pelvis/thorax/abdomen. These would definitely be very disturbing and troubling hallucinations to have to endure. They are possibly much more frightening than regular auditory hallucinations.
The patient actually benefited from 10 daily sessions of fMRI guided low frequency transcranial magnetic stimulation. They directed the TMS pulse over a brain area called the somatosensory cortex to reduce neuron activity their. This person had previously been treatment resistant to anti-psychotic therapy. The authors of the paper linked overactivation in the somatosensory cortex to the type of sensory hallucination that the person was experiencing.
I think this shows that TMS has a pretty good selectivity and scientists may be able to treat many currently treatment resistant patients. Brain areas can be selectively targeted for deactivation/activation as I have mentioned in the past. Better characterization of the changes induced by TMS by using real time brain imaging should help obtain even better responses.
3 comments:
I can't help but imagine the look on a lot of schizophrenics' faces when their psychiatrist recommends daily therapy involving a brain manipulation machine.
Especially if they're slacking on their meds.
Patients with schizophrenia are often just as interested as patients with other disorders in exploring novel treatments, especially as often their symptoms are so troubling and refractory to treatment.
Paul
This is an interesting field. I think it's plausible that TMS could help in cases of hallucinations, certainly more plausible than say for depression, where as far as I can see there is little theoretical basis for the treatment. they just TMS the frontal lobes because that's what (sometimes seems to!) work.
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