A quarterly publication of the Autism Research Institute

The Autism Research Review International is quarterly publication of the Autism Research Institute

Spring, 2016 | Number 2, Volume 30

Transcranial magnetic stimulation may improve symptoms in autism spectrum disorder

Repetitive transcranial magnetic stimulation (rTMS) may improve symptoms of autism, according to studies conducted by two separate groups of researchers. rTMS, a noninvasive procedure, involves creating magnetic pulses over the scalp via a magnetic coil. 

The first group of researchers, headed by Manuel Casanova, used rTMS to treat individuals younger than 18 years of age who were diagnosed with autism spectrum disorders (ASD). The researchers note, “Recent evidence suggests the symptoms of autism spectrum disorder may be related to an increased ratio of cortical excitation to inhibition.” Treatment with low-frequency rTMS has been shown to increase cortical inhibition by activating inhibitory circuits. 

The study involved approximately 200 individuals who received rTMS. The researchers measured the participants’ symptoms using neuropsychological questionnaires administered before and after rTMS. Using electroencephalographic (EEG) and event-related potential (ERP) tests, they also assessed participants’ selective attention and executive function skills. (Selective attention is the ability to focus on something without being distracted, while executive function is a term for skills including planning, impulse inhibition, and cognitive flexibility.) 

The researchers report, “Our preliminary findings in experimental studies using 6-, 12-, or 18-session long, low-frequency rTMS in children with ASD indicate significant improvement in EEG and ERP measures of selective attention and executive functioning, and also showed significant improvement in measures of irritability and repetitive/stereotyped behavior.” 

They conclude, “rTMS has the potential to become an important therapeutic tool in research and treatment and may play an important role in improving the quality of life for many individuals with ASD.” 

In separate research, Peter Enticott and colleagues treated adults with ASD using high-frequency rTMS to stimulate the dorsomedial prefrontal cortex. The first of two studies they conducted involved 28 individuals with ASD who received either active or sham deep rTMS each weekday for two weeks. The second study was an open-label study in which 20 individuals with ASD received 16 active treatments over four weeks. 

The researchers assessed the results in both studies using clinical and cognitive tests, and performed positron emission tomography (PET) scans on participants in the second study to assess brain glucose metabolism before and after treatment. They report that in the first study, participants in the active condition, but not those in the sham condition, reported a significant decrease in social impairment. Participants in the second trial also reported a decrease in social impairment, and PET scans showed evidence of enhanced glucose metabolism.


Citations

“Transcranial magnetic stimulation treatment: Focusing on core pathological features of autism spectrum disorders,” Manuel F. Casanova, presentation to the May 2016 International Meeting for Autism Research (IMFAR). 

—and— 

“Clinical trials of deep repetitive transcranial magnetic stimulation (rTMS) to bilateral dorsomedial prefrontal cortex in autism spectrum disorder,” Peter Enticott, presentation to the May 2016 International Meeting for Autism Research (IMFAR). 

—and— 

“Repetitive TMS may help core features of autism,” Pam Harrison, Medscape, May 18, 2016.