Cognitive Reserve Key Determinant of Schizophrenia Outcome

April 8, 2011 (Colorado Springs, Colorado) — Cognitive impairment can be present at the onset of schizophrenia, occurring over the transition to psychosis, and new research suggests that cognitive reserve at the onset of psychosis is a key determinant of outcome.

Eileen M. Joyce, MA, PhD, MRCP, FRCPsych, of UCL Institute of Neurology, London, United Kingdom, presented her team's ongoing research April 6 at the 13th International Congress on Schizophrenia Research in Colorado Springs, Colorado.

"Although cognitive impairment is well recognized as a central feature of schizophrenia, clinicians tend not to take this into account when formulating care plans of their patients when they first develop psychosis," she told Medscape Medical News.

The finding that cognitive impairment can be present at the start of the illness "is important because it will affect early occupational and social outcome," Dr. Joyce noted.

"Even though there are no specific medications yet available to remediate this impairment, taking cognition into account at psychosis onset would help in care planning so that daily function is optimized," she added.

Dr. Joyce and colleagues analyzed data from 2 separate cohorts from the West London First Episode Psychosis Study in which more than 180 patients were assessed for symptoms, social function, premorbid and current IQ, memory and executive function at psychosis onset, and on 2 subsequent occasions during 3 to 4 years.

Similar to patients with chronic schizophrenia, 40% of "first-episode" schizophrenia patients had evidence of generalized cognitive decline, whereas the remainder showed either preserved average/high IQ or low premorbid IQ that had not changed.

First-episode schizophrenia patients with low and deteriorated cognitive function were equally impaired on tests of memory and executive function compared with those with preserved average/high-IQ, and they displayed more negative and disorganization symptoms than the preserved average/high-IQ group.

There was clear evidence that cognitive reserve at the onset of schizophrenia is an important factor in clinical outcome.

Similar to Dementia?

"The concept of cognitive reserve comes from studies of neurodegenerative dementias, which find that higher IQ is somehow protective in that patients develop clinical features later despite having the same degree of pathology," Dr. Joyce told Medscape Medical News. "It's been suggested that this might also be the case for neurodevelopmental disorders such as schizophrenia," she explained.

Indeed, cognitive reserve at the beginning of psychotic illness was "the most important factor in determining 3- to 4-year clinical outcome, which in turn is known to predict long-term outcome," Dr. Joyce said.

Their research also provides evidence that, in a large proportion of patients, cognitive reserve itself may be affected by the pathological changes occurring in the frontal and temporal cortex during the transition to psychosis; "if this could be reversed or stopped from happening, the outcome of many patients would be more positive," Dr. Joyce said.

Reached for comment, Til Wykes, PhD, of Institute of Psychiatry, London, United Kingdom, who was not involved in the research, told Medscape Medical News that "it is clear that the results of reduced IQ are in line with current knowledge.

"Most importantly," Dr. Wykes said, the research shows that "reductions in IQ have consequences for social functioning in the future. It is possible that cognitive remediation might be a really good idea for those with reductions in IQ but also for others to increase cognitive reserve or to preserve what is there."

Dr. Joyce said "psychological methods of boosting cognitive reserve are currently being studied by several groups and hold promise for the near future."

The West London First Episode Psychosis Study is funded by the Wellcome Trust. Dr. Joyce and Dr. Wykes have disclosed no relevant financial relationships.

13th International Congress on Schizophrenia Research (ICSR): Abstract 978282. Presented April 6, 2011.