Both schizophrenia and hearing loss are independently associated with cognitive impairment, and the hearing-cognition relationship holds in schizophrenia, according to a study conducted by psychologists at NewYork-Presbyterian/
The study, published in Schizophrenia Research and led by NewYork-Presbyterian psychiatry and otolaryngology faculty, analyzed pure tone audiometry assessments among 84 adults with schizophrenia living in the community, as well as functional capacity and symptom severity. The results found that worse hearing was significantly correlated with worse cognitive performance, regardless of age, but was not associated with functional capacity or psychiatric symptoms.
“We know that hearing loss is associated with cognition if you don’t have a psychiatric illness. What we found was that if you do have a psychiatric illness like schizophrenia and cognitive impairment is associated with it, the hearing loss is further complicating matters,” says Alice Medalia, PhD, Director of the Lieber Recovery Clinic at NewYork-Presbyterian/
Dr. Medalia, who studies how to improve cognition among people with serious mental illnesses, had been investigating treatments for early auditory processing deficits — which impact the ability to discriminate the length, intensity, and pitch of non-verbal sounds — when she and her colleagues made an interesting discovery. As part of the initial testing for the study, schizophrenia patients had to undergo a hearing assessment, but the researchers were disqualifying more patients than expected due to previously undetected hearing loss.
Auditory Processing and Schizophrenia
Alice M. Saperstein, PhD, a psychologist at NewYork-Presbyterian/
Dr. Medalia and Dr. Saperstein performed an analysis of audiometry data collected among 84 community-dwelling adults ages 20-50 years with schizophrenia, and 81 age-matched healthy control subjects. The results, which were published in Psychiatric Services, showed that people with schizophrenia had worse hearing, even after controlling for age. Overall, 24% of those with schizophrenia had mild hearing loss, compared with 6% among age-matched controls without schizophrenia. The study did not address potential causes for the higher rate of hearing loss, though ototoxic medications, medical comorbidities, and noise exposures are all possible factors, explains Dr. Saperstein.
The Relationship Between Hearing Loss and Cognitive Impairment
In the general population, there is a significant body of research pointing to an association between hearing loss and cognitive impairment. Given that most patients with schizophrenia experience cognitive decline, Dr. Medalia and Dr. Saperstein wanted to better understand how these conditions correlated with one another. They brought in Justin S. Golub, MD, MS, an otologist/
“Cognitive impairment is a symptom of schizophrenia, impacting a majority of patients. The question was, what does hearing loss have to do with that? We know that it’s present in people without this diagnosis so what is happening in schizophrenia. The whole area is unnavigated,” says Dr. Medalia.
Their most recent study examined the correlates of hearing loss among adults, ages 22-50 years, with schizophrenia. Overall, cognitive functioning was significantly impaired and was correlated with worse hearing impairment. However, hearing impairment was not correlated with either functional capacity as measured by the Virtual Reality Functional Capacity Assessment Tool or with schizophrenia symptom severity as measured by the Positive and Negative Syndrome Scale.
“Cognitive impairment is a symptom of schizophrenia, impacting a majority of patients. The question was, what does hearing loss have to do with that? We know that it’s present in people without this diagnosis so what is happening in schizophrenia. The whole area is unnavigated.” — Dr. Alice Medalia
While the study establishes a connection between hearing loss and worse cognition among patients with schizophrenia, the cross-sectional nature of the analysis does not address why hearing loss is more common among patients with schizophrenia or why it appears to worsen cognition. Even without that information, the findings point to the need for hearing screening among patients with schizophrenia, explains Dr. Medalia.
Both studies were conducted in patients ages 50 years and younger, long before age-related hearing loss typically begins. This represents an unmet treatment need for younger patients with schizophrenia and suggests that routine hearing screening would be beneficial, says Dr. Medalia.
The research findings suggest that patients with schizophrenia may have undetected hearing loss.
Dr. Golub agrees that patients with schizophrenia should be screened for hearing loss at a younger age based on the higher prevalence in this patient population and the widespread availability of a noninvasive intervention – hearing aids.
“If one of the reasons why patients with schizophrenia tend to have worse cognition is that they also tend to get more hearing loss, then hearing loss might be an addressable risk factor for cognitive decline in these patients,” says Dr. Golub. “It is pretty straightforward to treat hearing loss compared to a lot of other conditions.”
“If one of the reasons why patients with schizophrenia tend to have worse cognition is that they also tend to get more hearing loss, then hearing loss might be an addressable risk factor for cognitive decline in these patients.” — Dr. Justin Golub
Additional research is needed to explore the etiology of hearing loss in schizophrenia as well as the clinical and public health significance of the findings. “Undetected hearing loss could have cognitive, social, and emotional implications for people with schizophrenia. It is important for these issues to be detected when people come in for routine health care,” says Dr. Saperstein.
