Now a new study led by psychologists at Beth Israel Deaconess Medical Center (BIDMC) found that certain neurocognitive symptoms tend to manifest first and are typically evident in the early, high-risk stage of the disorder called the prodromal phase.
The findings suggest that these deficits may serve as early warning signs of schizophrenia, as well as potential targets for intervention that could help curb the onset of the psychotic disorder and significantly improve cognitive function.
“To our knowledge, this is the largest and most definitive study of cognition in the high-risk period before onset of for psychosis/schizophrenia,” said corresponding author Larry J. Seidman, Ph.D., a psychologist at BIDMC and professor of psychology at Harvard Medical School.
“This is part of a paradigm shift in the way we are focusing on the earlier, prodromal phase of the disorder in an effort to identify those most likely to develop psychosis.”
For the study, the researchers gathered neurocognitive functioning data from participants at eight university-based, outpatient programs in the United States and Canada over the course of four years. They compared 689 males and females deemed at clinical high risk (CHR) of developing psychosis to 264 male and female healthy controls (HC).
The findings show that the high-risk group performed significantly worse than the control group on all measures, which involved tests of executive and visuospatial abilities, attention and working memory, verbal abilities, and declarative memory.
Among the high-risk participants only, those who would later go on to develop psychosis performed significantly worse than their high-risk peers who did not develop psychosis during the study.
“Currently, when mental health professionals assess people coming in for evaluation, we don’t know who will eventually develop schizophrenia,” said Seidman. “Our group’s focus is on identifying early warning signs and then developing interventions to improve a person’s chances for not getting it, making it milder or delaying it.”
Impaired working memory (the ability to hold information like a phone number in mind for a short time while it’s in use) and declarative memory (the ability to recall things learned in the last few minutes) turned out to be the key neurocognitive functions that are impaired in the high-risk, prodromal phase prior to the onset of full-blown psychosis.
These findings, said Seidman, confirm the experiences of many people with schizophrenia who report sudden difficulties reading, concentrating or remembering things in the earliest days of the disorder.
These cognitive deficits are the most difficult symptoms to treat and are responsible for keeping roughly 80 percent of people with schizophrenia out of work or school. New focus on the prodromal period and the growing promise of early intervention is giving patients and their families more realistic hope that better outcomes are possible, added Seidman.
“People can hear voices and still function pretty well, but they basically cannot function at all when their cognition is impaired,” he said.
“We are also testing a number of cognitive remediation and enhancement treatments to determine their role in the evolution of the illness. There’s more evidence suggesting that early intervention reduces the number of people who transition to schizophrenia.”
The study is published in the journal JAMA Psychiatry.