Neuropsychologic impairment largely present before psychosis onset
medwireNews: Much of the cognitive impairment associated with psychosis is present before the full onset of symptoms, say researchers, although there are some progressive neuropsychologic (NP) impairments that occur in the transition to psychosis.
Such impairments in NP performance were only moderate, but were most notable on tasks measuring cognitive flexibility and speeded visuospatial processing, with impairment in memory domains greater in high-risk individuals who went on to develop full-blown psychosis than in those who do not.
"Contrary to expectations, we did not find a significantly greater overall NP impairment at one year for CHR [clinical high risk] who developed psychosis relative to those who did not," the team notes in Schizophrenia Research.
Kristen Woodberry (Harvard Medical School, Boston, Massachusetts, USA) and colleagues examined NP functioning over 1 year in 53 individuals aged 12-25 years who were at CHR for psychosis and 23 mentally healthy individuals of a similar age.
The CHR participants had significantly lower overall NP functioning than predicted at 1 year, and significantly below-predicted scores for executive function and memory domains.
Specifically, within the executive function domain, Trail Making scores for CHR participants who did not develop full psychosis dropped from 9.4 at baseline to 9.2 at 1 year, while Wisconsin Card Sorting Test perseverative error scores improved only modestly, from 104.5 to 111.2. The corresponding scores for mentally healthy individuals increased from 9.9 to 10.7 and from 114.4 to 122.7.
On memory subtests, the CHR individuals not only failed to show the predicted improvement over time, but also demonstrated a slight decline from baseline.
The researchers report that among the CHR individuals, 10 developed severe and psychotic level symptoms, with all but one developing psychotic symptoms within 9 months of initial assessment.
Only progressive impairment in verbal memory test performance appeared to be greater among high-risk individuals who developed psychosis than those who did not, but not significantly so.
"A failure of normal development within verbal memory and EF [executive function] domains has implications for abnormal neuromaturation of ventral and dorsolateral prefrontal regions and frontotemporal networks," the researchers explain.
"A key question is whether early intervention (eg, cognitive remediation, neuroprotective agents) might facilitate normal neurodevelopment and associated improvements in NP functioning."
By Lucy Piper, Senior medwireNews Reporter