Emerging research suggests biological measurements may be used to help understand brain abnormalities found in schizophrenia and other disorders.
The biomarkers, known as endophenotypes, could ultimately help clinicians diagnose and treat the complex mental disorder.
“A major problem in psychiatry is that there are currently no laboratory tests that aid in diagnosis, guide treatment decisions or help predict treatment response or outcomes,” said Gregory A. Light, PhD.
“Diagnoses are currently based on a clinician’s ability to make inferences about patients’ inner experiences.”
Experts agree that diagnosing and treating schizophrenia is a particularly troubling challenge.
The disorder, which affects about one percent of the U.S. population or roughly three million people, is characterized by a breakdown of normal thought processes and erratic, sometimes dangerous or harmful, behaviors.
“Schizophrenia is among the most severe and disabling conditions across all categories of medicine,” said Light, who also directs the Mental Illness, Research, Education and Clinical Center at the San Diego VA Healthcare System.
The precise cause or causes of schizophrenia are not known, though there is a clear genetic component, with the disorder more common in some families.
Clinicians typically diagnose schizophrenia based upon inferences drawn from the patient’s inner experiences, that is, their ability to describe what’s happening inside their minds.
“But even the best clinicians struggle with diagnostic complexities based on sometimes fuzzy clinical phenomenology,” said Light.
The clinical challenge is compounded by the fact that “many schizophrenia patients have cognitive and functional impairments,” said Light. They may not be able to reasonably explain how or what they think.
In the study, Light and colleagues assessed if a battery of neurophysiological and neurocognitive biomarkers could provide clinicians with reliable, accurate, long-term indicators of brain dysfunction, even when overt symptoms of the disorder were not apparent.
These markers ranged from tests of attention and memory to physiological assessments of basic perceptual processes using scalp sensors to measure brain responses to simple sounds.
In the investigation researchers measured the biomarkers in 550 schizophrenia patients, and then re-tested 200 of the patients one year later.
They discovered most of the markers were significantly abnormal in schizophrenia patients, were relatively stable between the assessments and were not affected by modest fluctuations in clinical status of the patient.
Researchers say this is a positive beginning to determining functional biomarkers.
Additional studies are necessary to determine whether:
- The endophenotypes can differentiate other psychiatric disorders,
- If they can be used to anticipate patient response to different kinds of drugs or non-pharmacological interventions,
- If they can serve as a method to predict which subjects are at high risk of developing a psychotic illness.
“We believe this paper is an important step towards validating laboratory-based biomarkers for use in future genomic and clinical treatment studies of schizophrenia,” Light said.