![[Adobe Stock]](https://sp-ao.shortpixel.ai/client/to_webp,q_glossy,ret_img,w_750,h_375/https://www.psypost.org/wp-content/uploads/2025/03/brain-MRI-scans-750x375.jpg)
A recent study found that individuals with treatment-resistant schizophrenia exhibit specific structural differences in their brains, including a smaller hippocampus, compared to patients who respond to standard medications. These anatomical variations could eventually help doctors identify which patients are unlikely to benefit from typical antipsychotic drugs, allowing for earlier alternative interventions. The research was published in the journal Molecular Psychiatry.
Schizophrenia is a psychiatric condition characterized by hallucinations, delusions, and cognitive impairments. Standard antipsychotic medications primarily work by blocking dopamine receptors in the brain, which effectively reduces symptoms for many individuals. However, up to 60 percent of patients do not experience adequate symptom relief from these standard drug therapies. This condition, known as treatment-resistant schizophrenia, presents major challenges in psychiatric care.
The only medication currently approved for this specific population is clozapine. Its administration requires strict blood monitoring due to the risk of severe immune system complications, and a substantial portion of patients still fail to respond to it. Medical professionals currently diagnose treatment resistance only after a patient has failed to improve following multiple trials of different antipsychotic drugs. This trial-and-error process can take months or years, during which the patient’s mental health often deteriorates.
An objective biological marker could allow doctors to bypass this waiting period and initiate specialized therapies immediately. A team of researchers led by Semra Etyemez, Kun Yang, and Akira Sawa at the Johns Hopkins University School of Medicine investigated whether specific brain structures differ in patients with treatment resistance. Prior smaller studies had hinted at anatomical changes, but the researchers needed a broader dataset to verify these patterns.
Don’t miss the next big psychology finding
Every morning, PsyPost sends a short briefing on the most interesting new peer-reviewed research in psychology and neuroscience.
The research team collaborated with an international neuroimaging consortium to gather brain scan data from more than 1,200 individuals across seven sites in six countries. The dataset included 158 patients with treatment-resistant schizophrenia, 599 patients whose symptoms responded to standard treatments, and 508 healthy individuals. Medical professionals at each site classified the patients based on their comprehensive clinical and medication records.
In their first analysis, the researchers conducted a meta-analysis, an approach that aggregates the results of multiple independent datasets to identify overarching trends. They compared the volume of various deep brain structures, as well as the thickness and surface area of the brain’s outer layer, between the two groups of patients. To ensure accuracy, the team adjusted their statistical models to account for variables like age, sex, race, head size, and illness duration.
The researchers found that patients with treatment-resistant schizophrenia had reduced tissue volume in both the left and right sides of the hippocampus, a seahorse-shaped structure buried deep in the brain that is essential for memory and learning. The treatment-resistant group also showed reduced volume in the putamen, a round structure at the base of the brain involved in learning and motor control. Additionally, these patients had a reduced surface area in the left superior frontal gyrus, a region located near the front of the brain that plays a role in cognitive processing.
To verify these results, the team performed a mega-analysis, pooling all the raw brain scan data into one unified dataset rather than just combining the statistical summaries from each site. During this phase, they also integrated the data from the healthy individuals to establish a baseline for normal brain anatomy. This allowed the researchers to observe the anatomical trajectory across the different groups.
The mega-analysis confirmed the structural reductions in the hippocampus, putamen, and left superior frontal gyrus. When comparing all three groups, the researchers observed a sequential pattern in the hippocampus and the superior frontal gyrus. Healthy individuals had the largest tissue volumes in these areas, patients responsive to typical treatments had smaller volumes, and patients with treatment resistance had the smallest.
The putamen did not follow this stepwise pattern. The researchers observed no statistical difference in the size of the putamen between treatment-resistant patients and healthy individuals. Instead, the putamen was actually larger in patients who responded to standard treatments compared to the healthy control group.
Because the patients had taken different types and amounts of medication over varying periods, the researchers tested whether the structural differences were simply side effects of the drugs. They analyzed the relationship between the anatomical measurements and the cumulative dosage of antipsychotics each patient had received. They also specifically checked for correlations with clozapine use.
The analysis revealed that medication dosage was not statistically significant in relation to the size of the hippocampus or the surface area of the superior frontal gyrus. This lack of association suggests that the shrinkage in these areas relates to the underlying biology of treatment-resistant schizophrenia itself, rather than the medications used to treat it. The volume of the putamen did show a weak correlation with cumulative medication use, indicating that antipsychotic drugs might slightly influence the size of this specific structure.
While the study utilized data from six countries in North America, Europe, and Asia, the research team noted that the participant pool lacked representation from African and Latino populations. Expanding future neuroimaging initiatives to include more diverse demographics will help confirm whether these anatomical differences remain consistent across all human populations. Additionally, the group of patients classified as responsive to treatment might include individuals who will develop treatment resistance later in life.
The structural differences identified in the hippocampus and superior frontal gyrus are not yet sufficient to serve as a standalone diagnostic tool. When the researchers tested the predictive power of these brain measurements, the models could not reliably distinguish treatment-resistant patients from other patients with schizophrenia on an individual basis. Moving forward, scientists will likely need to combine brain imaging with other biological indicators, such as genetic profiles or metabolic markers, to create a reliable predictive test for clinical settings.
The study, “Brain structural abnormalities in treatment-resistant schizophrenia,” was authored by Semra Etyemez, Rohit Sivananthan, Andreia V. Faria, Felice Iasevoli, Giuseppe Pontillo, Annabella Di Giorgio, Young-Chul Chung, Woo-Sung Kim, Soyolsaikhan Odkhuu, Jun Soo Kwon, Minah Kim, Minji Ha, Foivos Georgiadis, Beatrice A. Milano, Matthias Kirschner, Stefan Kaiser, Diana Tordesillas-Gutiérrez, Kang Sim, Yunlong Tan, Sherry Kit Wa Chan, Jessica A. Turner, Theo G. M. van Erp, Jimmy Lee, Vince D. Calhoun, Akira Sawa, and Kun Yang.
