Background. We tested the hypothesis that schizophrenia
is primarily a frontostriatal disorder by
examining executive function in first-episode patients. Previous studies
have shown either equal
decrements in many cognitive domains or specific deficits in memory.
Such studies have grouped test
results or have used few executive measures, thus, possibly losing information.
measured a range of executive ability with tests known to be sensitive
to frontal lobe function.
Methods. Thirty first-episode schizophrenic patients and 30
volunteers, matched for age and
NART IQ, were tested on computerized test of planning, spatial working
memory and attentional
set shifting from the Cambridge Automated Neuropsychological Test Battery.
traditional tests of memory were also administered for comparison.
Results. Patients were worse on all tests but the profile was
non-uniform. A componential analysis
indicated that the patients were characterized by a poor ability to think
ahead and organize
responses but an intact ability to switch attention and inhibit prepotent
responses. Patients also demonstrated poor memory, especially for free
recall of a story and
associate learning of unrelated word pairs.
Conclusions. In contradistinction to previous studies,
schizophrenic patients do have profound
executive impairments at the beginning of the illness. However, these
concern planning and strategy
use rather than attentional set shifting, which is generally unimpaired.
Previous findings in more
chronic patients, of severe attentional set shifting impairment, suggest
that executive cognitive
deficits are progressive during the course of schizophrenia. The finding
of severe mnemonic
impairment at first episode suggests that cognitive deficits are not
restricted to one cognitive domain.