With every psychiatric drug taken, researchers are seeing shifts in people’s brain waves. This was shown in an August study of more than 24,000 electroencephalogram (EEG) recordings published in the journal eBioMedicine.
Medications used to treat the same condition are not necessarily interchangeable and may differ in how they affect the brain, Magdalena Szponar, a doctoral student in the Laboratory of Neurophysiology of Mind and the study’s lead author, told The Epoch Times.
The researchers analyzed clinical EEG recordings from two psychiatric hospitals in Warsaw, Poland. They found that benzodiazepines, selective serotonin reuptake inhibitors (SSRIs), antipsychotics, and anticonvulsants each left a distinct signature on the brain’s electrical activity, consistent with the different ways they act on the brain.
Different medications may affect different neurotransmitter systems and receptors, resulting in different EEG patterns, Szponar said.
This finding matters beyond the lab. Choosing a psychiatric medication can often be trial and error—weeks on one drug, then a switch, then more waiting. If EEG signatures can eventually help predict which patients respond well to which drugs, that could shorten the search for the right treatment.
How Different Drugs Affect the Brain
Changes in these patterns have been associated with various cognitive and behavioral states, and some are broadly consistent with the known effects of psychotropic medications, Szponar said.
Benzodiazepines
Benzodiazepines act as sedatives. They slow down brain activity and the central nervous system, alleviate anxiety symptoms, and reduce muscle spasms and seizures.
Counterintuitively, the study found that benzodiazepines increased beta activity, a faster brain-wave pattern often associated with alertness and active information processing, Szponar said, while reducing slower theta-alpha activity linked to “attention, memory, and emotional processing.”
These EEG changes appear consistent with another study’s finding that, while benzodiazepines may help people fall asleep faster and stay asleep longer, they suppress deep, restorative sleep.
As a hypothesis for future studies, Szponar suggested that “increased beta power associated with benzodiazepine treatment may be possibly linked to impaired motor coordination.”
SSRIs and Related Antidepressants
SSRIs are antidepressants prescribed to relieve moderate or severe depression. The study grouped SSRIs with serotonin modulators and stimulators (SMS), another type of antidepressant.
The study found that SSRIs were associated with increased synchronization between brain regions in the high-frequency gamma range—a pattern thought to support communication across brain networks. The gamma band has been linked to memory, attention, motor function, sensory processing, and cognitive-emotional processing.
Common side effects of SSRIs include nausea, vomiting, insomnia, drowsiness, headache, decreased sex drive, and agitation.
Antipsychotics and Anticonvulsants
Antipsychotics and anticonvulsants—the former used mainly for psychosis, the latter for seizures and sometimes anxiety disorders or nerve pain—both showed increased activity in the theta and low-alpha ranges.
Theta waves occur during REM sleep, while alpha waves commonly occur during wakeful rest. Both are linked to memory formation.
Szponar suggested that these changes could “be related to effects such as sedation or cognitive slowing.”
Furthermore, medications used to treat the same condition may affect the brain differently and may not be interchangeable. For example, Szponar said that typical and atypical antipsychotics affected several EEG measures in opposite ways, including signal complexity and gamma connectivity.
While the detected EEG changes may relate to several psychological and physiological effects, and some align with known effects and findings from other studies, Szponar emphasized that it would be premature to infer specific effects on attention, emotion, or cognition, and some of these relationships remain hypotheses that require further study.
So What Does a Brain-Wave Change Actually Mean?
The changes in EEG in this study confirmed that psychiatric drugs change the normal state of the brain’s physiology, Dr. Joanna Moncrieff, a psychiatrist and professor of critical and social psychiatry at University College London, told The Epoch Times.
“These brain physiology alterations will be reflected in the manner in which they alter normal consciousness, emotions, and cognition, etc.,” she said.
Moncrieff offered a broader pattern across drug types. Many psychiatric drugs—including SSRIs, antipsychotics, and stimulants—can dampen emotions. Others, such as benzodiazepines and alcohol, can sometimes make emotions more unpredictable. Antipsychotics, she said, often slow people down mentally; stimulants can improve performance on simple cognitive tasks but may reduce flexibility and creativity without improving performance on complex tasks.
The same drugs can affect people differently.
“People’s brains differ in their anatomy, connectivity, and functioning, as they are shaped by genetics and experience,” Szponar said.
Even symptoms can differ among people with the same diagnosis.
“A drug that shifts brain activity in a particular direction may therefore be beneficial for one person but less useful—or produce unwanted effects—in another,” she said.
In the longer term, Szponar said that EEGs could become useful for more individualized treatment.
“One possibility would be to record EEG before treatment,” Szponar said.
Such a recording could provide additional information about a person’s brain activity and help identify any unusual activities that might be connected to their symptoms.
Researchers could then ask which medications are more or less likely to normalize those abnormalities.
For now, Szponar emphasized, choosing the right psychiatric medication remains a decision for a clinician based on a patient’s medical history, needs, and a careful weighing of a drug’s effectiveness against its potential side effects.
