Researchers Seek Early Markers of Schizophrenia, With Remediation in Mind
October 24, 2012
by Robin Tricoles
Researchers know that genetics plays a role in the development of schizophrenia; yet, symptoms often don’t surface until adolescence or young adulthood. But those who go on to develop the disease may show early signs long before symptoms appear.
Psychologist Deanna Barch is exploring what she and other scientists see as early markers of schizophrenia, impairments in cognition and in brain function. Such markers could help identify people who are most at risk for developing the disease, such as those with close relatives with schizophrenia.
“If you have a brother or sister with schizophrenia your likelihood of developing the disease is more like 10 or 15 percent compared with only 1 percent of the general population, says Barch, an expert on schizophrenia and brain imaging. Schizophrenia is a brain disorder characterized by hallucinations and delusions as well as thought and movement disorders.
“One of the things that characterizes people with schizophrenia is they have substantial impairment in cognitive function,” says Barch. “They seem to have a lot of difficulty activating certain brain regions when they’re doing cognitively demanding tasks. And doing poorly on these tasks and failing to activate these brain regions is associated with poor function and poor outcome for patients with schizophrenia.”
But does the same hold true for those who have not yet developed the disease but are at risk? To find out, Barch looks at high-risk individuals’ working memory; that is, their ability to control attention while executing a cognitively demanding task.
“What we’re starting to see is that the siblings of people with schizophrenia also have difficulties with cognitive challenges, says Barch. “Not to the same degree as those who have the illness, but they certainly have more challenges on average than a healthy control population. Further, the siblings who show some of the behaviors analogous to the symptoms by which we diagnose this illness do the worst on these cognitive tasks and have the worse neurobiological impairment.”
To measure cognitive function, researchers image the brain while someone performs a memory-related task that involves recalling a series of items such as words, letters, or pictures. Researchers can then vary the difficulty of that task to gauge the degree to which the brain can modulate activity to meet increases in cognitive demand. For example, a very low memory load would involve showing a respondent a series of letters, and then asking him to push a button every time he or she sees a particular letter or to push a different button when he sees another letter. Memory load could then be increased by asking the person to push a button every time the current letter is one seen two letters previously, and so on.
“That’s where folks with schizophrenia start to have difficulties because that kind of memory load is thought to be dependent on the prefrontal cortex and its interaction with other cognitive control brain regions,” says Barch.
Likewise, those in high-risk groups who have yet to develop schizophrenia may also start having cognitive difficulties when memory load is increased. “We have some evidence that poor performance on tasks like that are correlated with increased preclinical symptoms of the illness,” says Barch.
Which is where cognitive remediation, literally exercising the brain with cognitive tasks, may help those already diagnosed with schizophrenia, or even those in high-risk populations, head off the disease.
“Because the brain is plastic, you’re actually changing wiring and connections in the brain in a way that supports development,” says Barch. In the case of schizophrenia, researchers have been looking at a wide variety of auditory processing and auditory memory tasks, as well as visual tasks, as a path to cognitive remediation.
“You start with a doable task and you progressively make it harder and harder with the idea being that what you’re doing is you’re pushing the brain to rewire and reorganize in a way to accomplish these tasks.”
So far, most cognitive remediation research has involved people who have already been diagnosed with the disease, says Barch. “But we’re starting to apply it now to high-risk populations as well, with the idea that maybe it would improve cognitive function and lower the risk of psychosis.
If you’re helping to strengthen parts of the brain that would normally be involved in symptom development or symptom expression that’s one way you could prevent it. There’s a more indirect way though. If cognition and impaired cognition make it difficult to live your life and creates a lot of stress, if you enhance cognition and reduce stress, and make life more manageable that in itself might reduce the conversion rate for psychosis.”
Deanna Barch is a professor of Psychology, Psychiatry and Radiology at Washington University in St. Louis and co-director of the Cognitive Control and Psychopathology (CCP) Laboratory. Barch studies cognitive and language deficits in disorders such as schizophrenia, and the neurobiological mechanisms that contribute to such deficits. Barch is a member of the Society for Research in Psychopathology, one of FABBS' 22 member societies.