Study design compared a) a single session of transcranial magnetic stimulation to b) an accelerated, multi-session protocol. Each group of participants received pre- and post-session neuroimaging and cognitive assessments.
Cognitive deficits are a leading cause of disability in schizophrenia. Most profoundly impaired is the ability of the brain to rapidly process information.
Now, researchers at Vanderbilt Health and Harvard Medical School show in two small groups of adults with schizophrenia or schizoaffective disorder that processing speed can be improved and cognitive impairment reduced, particularly in younger individuals, by targeting a specific site in the brain with transcranial magnetic stimulation (TMS).
Their findings were published Aug. 5 in the journal Molecular Psychiatry.
While further study is needed, TMS could lead to the first effective treatment for cognitive impairment in schizophrenia, said the paper’s corresponding author, Heather Burrell Ward, MD, Director of Neuromodulation Research at Vanderbilt Health.
“Many of my patients with schizophrenia struggle with things like attention, concentration and processing speed,” Ward said. “While antipsychotic medications are helpful for many symptoms of psychosis, there are currently no approved medications for cognitive deficits.
“We are excited about these results, which suggest that TMS may be an effective treatment for cognitive deficits in schizophrenia.”
TMS is a noninvasive procedure in which a magnetic coil placed on the scalp generates magnetic pulses that pass through the skull and, by inducing small electrical currents, modulate neural activity in targeted areas of the brain.
Ward, Assistant Professor of Psychiatry and Behavioral Sciences, and her colleagues have been leaders in the development of TMS as a treatment for psychotic disorders, like schizophrenia, and substance use.
“Unlike medications, TMS has localized effects — we are applying it to the brain regions that are most affected,” she said. “Importantly, TMS is safe and well tolerated by people with psychosis.”
In the current study, the researchers targeted an area of the brain called the default mode network (DMN). Hyperconnectivity in this area has been associated with deficits in processing speed. Suppression of DMN activity, which is required for normal cognitive function, is impaired in schizophrenia.
One group of 10 individuals with schizophrenia received single TMS sessions.
A second group of 17 individuals with schizophrenia or schizoaffective disorder (those with symptoms of both schizophrenia and mood disorders) received five sessions of continuous theta burst stimulation, an advanced, faster form of TMS, during a one-day accelerated protocol.
The two study groups had pre- and post-session neuroimaging and cognitive assessments.
Processing speed did not change in the single-session group but improved significantly in the multi-session group.
Greater improvement in processing speed also was observed in younger participants, suggesting that accelerated brain aging, loss of plasticity and longer exposure to antipsychotic medications, which have been associated with cognitive impairment in psychosis, may limit the effectiveness of this treatment in older individuals.
Jillian Connolly, research assistant in Psychiatry, is the paper’s first author.
Other Vanderbilt Health co-authors are Sophia Blyth, research assistant; Gulcan Yildiz, MD, psychiatry resident; Baxter Rogers, PhD, Research Professor of Radiology and Radiological Sciences; and Simon Vandekar, PhD, Associate Professor of Biostatistics.
The study was supported in part by the Sidney R. Baer Jr. Foundation, the Harvard Medical School Norman E. Zinberg Fellowship for Addiction Psychiatry Research, the Vanderbilt Kennedy Center, and National Institutes of Health grants R01MH116170, KL2TR002245 and K23DA059690.
Ward recently received a $100,000 grant from the Sidney R. Baer Jr. Foundation to further develop TMS to improve cognitive deficits in schizophrenia. She will test a novel accelerated protocol of 25 TMS sessions to produce sustained improvements in cognitive performance.
