The Propensity to Hear “Voices” in Schizophrenia May Be Established by Infancy, Many Years Before Symptom Onset
Findings reveal how auditory hallucinations may arise in patients with schizophrenia and provide potential new targets for early detection and treatment
Some people suffering from severe mental illness, particularly schizophrenia, hear “voices,” known as auditory hallucinations. This symptom, which afflicts more than 80% of patients, is among the most prevalent and distressing symptoms of schizophrenia. Patients “hear voices” speaking to them or about them without anyone actually being there. Auditory hallucinations, which usually begin in adolescence and young adulthood, “sound” very real to patients and can have a devastating impact on their quality of life because the “voices” are typically distressing and distracting, sometimes compelling the sufferer into suicidal or violent actions. Uncovering the biological origins of auditory hallucinations is essential for reducing their contribution to the disease burden of schizophrenia.
To investigate the biological origins of hearing “voices” in patients with schizophrenia, a team led by researchers at the Icahn School of Medicine at Mount Sinai used ultra-high field imaging to compare the auditory cortex of schizophrenic patients with healthy individuals. They found that schizophrenic patients who experienced auditory hallucinations had abnormal tonotopic organization of the auditory cortex. Tonotopy is the ordered representation of sound frequency in the auditory cortex, which is established in utero and infancy and which does not rely on higher-order cognitive operations. The study findings, which appears this week in the Nature Partner Journal NJP Schizophrenia, suggest that the vulnerability to develop “voices” is probably established many years before symptoms begin.
“Since auditory hallucinations feel like real voices, we wanted to test whether patients with such experiences have abnormalities in the auditory cortex, which is the part of the brain that processes real sounds from the external environment,” says Sophia Frangou, MD, PhD, Professor of Psychiatry at the Icahn School of Medicine at Mount Sinai. “
Specifically, the research team used an ultra-high field scanner with a powerful 7 Tesla magnet to obtain high-resolution images of brain activity while study participants listened passively to tones across a range of very low to very high frequencies. In healthy brains, these sounds are processed in a very organized fashion; each frequency activates a specific part of the auditory cortex forming a tonotopic map. The team obtained tonotopic maps from 16 patients with schizophrenia with a history of recurrent auditory hallucination and 22 healthy study participants. They found that patients showed greater activation in response to most sound frequencies. Additionally, the mapping of most sound frequencies to parts of the auditory cortex appeared “scrambled” in patients with schizophrenia, suggesting that the normal processes for the organized representation of sound in the brain are disrupted in schizophrenia.
“Because the tonotopic map is established when people are still infants and remains stable throughout life, our study findings suggest that the vulnerability to develop “voices” is linked a deviance in the organization of the auditory system that occurs during infancy and precedes speech development and the onset of psychotic symptoms by many years. This is particularly exciting because it means that it might be possible to identify potential vulnerable individuals, such as the offspring of schizophrenia patients, very early on.”
According to the authors, in addition to helping doctors spot people who are likely to experience hallucinations before the symptoms appear or become severe, the auditory cortex may be an area of consideration for novel neurmodulation methods to help patients who already have symptoms.
Looking ahead, Dr. Frangou’s research team will replicate and expand the current observations in larger samples to determine their relevance to hallucinations across diagnoses and to quantify the association of tonotopic disruption to auditory cortical activation and connectivity during actual hallucinatory experiences.
The study was supported by the National Institutes of Mental Health, the National Cancer Institute, The Netherlands Organisation for Health Research and Development, the Stanley Foundation and the Brain and Behavior Research Foundation.
About the Mount Sinai Health System
Mount Sinai Health System is one of the largest academic medical systems in the New York metro area, with 48,000 employees working across eight hospitals, more than 400 outpatient practices, more than 600 research and clinical labs, a school of nursing, and a leading school of medicine and graduate education. Mount Sinai advances health for all people, everywhere, by taking on the most complex health care challenges of our time—discovering and applying new scientific learning and knowledge; developing safer, more effective treatments; educating the next generation of medical leaders and innovators; and supporting local communities by delivering high-quality care to all who need it.
Through the integration of its hospitals, labs, and schools, Mount Sinai offers comprehensive health care solutions from birth through geriatrics, leveraging innovative approaches such as artificial intelligence and informatics while keeping patients’ medical and emotional needs at the center of all treatment. The Health System includes approximately 9,000 primary and specialty care physicians and 11 free-standing joint-venture centers throughout the five boroughs of New York City, Westchester, Long Island, and Florida. Hospitals within the System are consistently ranked by Newsweek’s® “The World’s Best Smart Hospitals, Best in State Hospitals, World Best Hospitals and Best Specialty Hospitals” and by U.S. News & World Report's® “Best Hospitals” and “Best Children’s Hospitals.” The Mount Sinai Hospital is on the U.S. News & World Report® “Best Hospitals” Honor Roll for 2024-2025.
For more information, visit https://www.mountsinai.org or find Mount Sinai on Facebook, Twitter and YouTube.