Calculating the Value of Effortful Behavior: A Clue to Schizophrenia-Related Disability?
From a new study in Biological Psychiatry
From a new study in Biological Psychiatry
Many people with schizophrenia have marked problems with motivation, failing to initiate and persist in goal-directed behavior. These negative symptoms of schizophrenia can be disabling and prevent individuals from realizing their potential.
For many years it was thought this was due to an inability to experience pleasure associated with successful goal attainment. However, recent laboratory studies have shown that hedonic experience is actually intact in people with schizophrenia, calling for new approaches to better understand these motivational deficits.
In a new study published in Biological Psychiatry, Dr. James Gold, at the University of Maryland School of Medicine, and his colleagues now provide a new clue to the relationship between motivational deficits and functional impairment.
They theorized that the lack of motivation may stem from a decreased willingness to expend effort to gain rewards. In other words, individuals with schizophrenia may be less able to properly evaluate future reward in terms of the 'cost' of the effort required.
To test this, the researchers recruited individuals with schizophrenia and a comparison group of healthy individuals. The individuals with schizophrenia were also evaluated for their symptom levels. All participants completed a computerized effort-cost decision-making task in the laboratory. This task required them to make decisions between two alternatives: an easy option with a minimal reward, and a harder option with a higher-value reward.
They found that schizophrenia patients, especially those with prominent negative symptoms, were more likely to choose the less demanding tasks that provided smaller rewards and were less likely than healthy subjects to choose more demanding tasks that offered greater rewards.
"In essence, patients with severe negative symptoms calculate the 'cost' of potential effort versus the value of potential awards using a different equation than healthy volunteers or other people with schizophrenia who do not have severe motivational problems. The cost of effort is more salient than the potential increase in reward value," explained Gold.
These findings suggest that negative symptoms are associated with abnormalities in how patients weigh the cost of the effort needed to receive a reward or reach a goal. Importantly, these abnormalities were seen consistently only in those patients with high levels of negative symptoms. It seems that these patients were particularly averse to the higher effort required for larger rewards and/or that they did not find the higher reward worth the extra effort required.
Dr. John Krystal, Editor of Biological Psychiatry, commented, "It is important to understand the disadvantageous choices that patients make because it may be possible, through education, rehabilitation, and perhaps medication to help patients make better progress in their rehabilitation."
The article is "Negative Symptoms of Schizophrenia Are Associated with Abnormal Effort-Cost Computations" by James M. Gold, Gregory P. Strauss, James A. Waltz, Benjamin M. Robinson, Jamie K. Brown, and Michael J. Frank (doi: 10.1016/j.biopsych.2012.12.022). The article appears in Biological Psychiatry, Volume 74, Issue 2 (July 15, 2013), published by Elsevier.
Notes for Editors
Full text of the article is available to credentialed journalists upon request; contact Rhiannon Bugno at +1 214 648 0880 or Biol.Psych@utsouthwestern.edu. Journalists wishing to interview the authors may contact Dr. James Gold at +410 402 7871 or firstname.lastname@example.org.
The authors' affiliations, and disclosures of financial and conflicts of interests are available in the article.
John H. Krystal, M.D., is Chairman of the Department of Psychiatry at the Yale University School of Medicine and a research psychiatrist at the VA Connecticut Healthcare System. His disclosures of financial and conflicts of interests are available here.
About Biological Psychiatry
Biological Psychiatry is the official journal of the Society of Biological Psychiatry, whose purpose is to promote excellence in scientific research and education in fields that investigate the nature, causes, mechanisms and treatments of disorders of thought, emotion, or behavior. In accord with this mission, this peer-reviewed, rapid-publication, international journal publishes both basic and clinical contributions from all disciplines and research areas relevant to the pathophysiology and treatment of major psychiatric disorders.
The journal publishes novel results of original research which represent an important new lead or significant impact on the field, particularly those addressing genetic and environmental risk factors, neural circuitry and neurochemistry, and important new therapeutic approaches. Reviews and commentaries that focus on topics of current research and interest are also encouraged.
Biological Psychiatryis one of the most selective and highly cited journals in the field of psychiatric neuroscience. It is ranked 4th out of 135 Psychiatry titles and 13th out of 251 Neurosciences titles in the Journal Citations Reports® published by Thomson Reuters. The 2012 Impact Factor score for Biological Psychiatry is 9.247.
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