Psychiatric News June 18, 2004
Volume 39 Number 12
© 2004 American Psychiatric Association
p. 29
Psychotic Depression May Be Relative of Schizophrenia
Joan Arehart-Treichel
Psychotic depression and schizophrenia probably have different origins
in the brain, but they may end up sharing a common pathway regarding their
impact on neurocognitive abilities.
What is the neuropsychology of psychotic depression anyway—is it more
closely related to schizophrenia or to depression? A new, rigorously
controlled study suggests that it is a lot closer to
schizophrenia.
The study was headed by S. Kristian Hill, Ph.D., of the Center for
Cognitive Medicine at the University of Illinois at Chicago and appeared in
the June American Journal of Psychiatry.
The neuropsychological profile of psychotic depression, especially in early
and mid adulthood, has received little investigation. Data are inconsistent,
often methodologically limited, and potentially confounded by the effects of
chronic disease and exposure to antipsychotic treatment. So Hill and her
colleagues studied whether the neuropsychology of psychotic depression is
closer to that of schizophrenia or that of nonpsychotic depression.
They recruited 106 patients who were consecutively admitted to the
University of Pittsburgh Medical Center for a psychotic disorder on the basis
of the Structured Clinical Interview for DSM-III-R or DSM-IV
(SCID). Of the 106 patients, 86 were diagnosed with a schizophrenia spectrum
disorder or schizoaffective disorder and the 20 with unipolar depression with
psychotic features.
Before any of these patients were treated for their psychosis, they were
given a battery of neuropsychological tests that assessed general
intelligence, executive function, attention, verbal memory, motor skills, and
visuospatial perception. At the time of neuropsychological testing, the
examiners were unaware of the subjects' diagnoses.
"To our knowledge," the researchers asserted in their study
report, "this is the first study to provide data that document the
neuropsychological profile of psychotic depression in young adults at the time
of the first episode of illness, before treatment with antipsychotic
medication."
The scientists then selected 14 other patients who had been diagnosed as
having a nonpsychotic unipolar depression, as well as 81 healthy individuals
with no history of psychiatric treatment and no Axis I disorder.
The unipolar depression patients stopped taking antidepressant medication
for at least three weeks before the start of the study to avoid a direct
medication effect on the study results. The investigators also ensured that
these subjects matched the 106 subjects with either a schizophrenia disorder
or a psychotic depression on gender, race, education, and parental
socioeconomic status. These subjects also completed a battery of
neuropsychological tests.
The researchers then assessed the neuropsychological test results from
their four groups of subjects.
The subjects with psychotic depression were found to have a pattern of
neuropsychological dysfunction that was similar to, but less severe than, that
of the subjects with a schizophrenia disorder, the investigators found. In
contrast, subjects with nonpsychotic unipolar depression had a
neuropsychological profile that was similar to that of the healthy control
subjects, except for mild dysfunction on tests of attention.
These results, the researchers maintained, suggest that schizophrenia and
psychotic depression "may have common pathophysiological
features." And as far as the implications of the findings for clinical
psychiatrists are concerned, "they provide further documentation that
psychotic depression involves significant neuropsychological
impairment," Michael Thase, M.D., a professor of psychiatry at the
University of Pittsburgh, and one of the study collaborators, told
Psychiatric News. The study was financed by the National Alliance for
Research on Schizophrenia and Depression and the National Institutes of
Health.
The study, "Neuropsychological Dys-function in
Antipsychotic-Naive First-Episode Unipolar Psychotic Depression," is
posted online at
<http://ajp.psychiatryonline.org/cgi/content/full/161/6/996>.
Am J Psychiatry 2004 161 996[Abstract/Free Full Text]
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