Cognitive dysfunction in psychiatric patients: Comparison between schizophrenic and bipolar disorder patients with healthy subjects / Sylvia Wong Tyng Yng
Background and Objective: The debate regarding the similarities and differences in cognitive functions in remitted schizophrenia and bipolar patients continues to be ongoing. This study was done to compare the level of cognitive functions as well as to determine associated factors influencing the...
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| Format: | Thesis |
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2017
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| Online Access: | http://studentsrepo.um.edu.my/11614/ http://studentsrepo.um.edu.my/11614/4/sylvia.pdf |
| Summary: | Background and Objective: The debate regarding the similarities and differences in
cognitive functions in remitted schizophrenia and bipolar patients continues to be
ongoing. This study was done to compare the level of cognitive functions as well as to
determine associated factors influencing the cognitive functions of these patient
populations with those of a healthy subject group.
Methodology: This was a cross sectional study on stable schizophrenic and euthymic
bipolar patients and healthy subjects. Subjects were included after screening through
stringent inclusion and exclusion criteria, along with healthy subjects. The cognitive
assessment tools used were the perceived deficits questionnaire (PDQ) (subjective
assessment), the trail making tests (TMT), and the digit span. TMT A was to measure
attention, TMT B and reverse Digit Span task measured executive functions, whereas
the forward Digit Span task measured working memory.
Results: Fifty-seven stable schizophrenic patients and forty euthymic bipolar patients as
well as fifty-seven healthy subjects were included in the study. Stable schizophrenic
patients did significantly poorly in all the objective tests (p<0.01) in comparison with
the bipolar and healthy group. In the TMT A which measures attention, schizophrenic
patients took 48.93 seconds on average, while on the TMT B, measuring executive
function, they took 116.67 seconds. In comparison, the bipolar group spent 34.51
seconds on the TMT A, and 79.90 seconds on the TMT B. The healthy group used the
least time to complete the tests, which was 23.98 seconds for the TMT A and 48.82
seconds in the TMT B. The bipolar group performed better than the schizophrenic
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group but fared worse than the healthy group in all the tests except the digit span
forward test, which measures working memory (p=0.857).
There were several demographic factors that were associated with poorer performance
in the TMT and digit span tasks, namely more advanced age, Indian ethnicity, fewer
years of education, being unemployed and longer duration of illness. After adjusting for
those variables in multivariate analysis, the schizophrenia group performed significantly
poorer than the healthy group in the TMT A and reverse digit span task (which
measures executive function), and more advanced age and Indian ethnicity were
independent risk factors for poorer performance in TMT A. The bipolar group
performed significantly poorer than the healthy group in the TMT B and reverse digit
span task. Indian ethnicity and less years of education were independent risk factors for
poor performance in TMT A, and Chinese ethnicity performed better in the TMT B.
Conclusion: Cognitive dysfunction was found to be present in stable schizophrenic and
bipolar patients. In the schizophrenia group, the cognitive dysfunctions found were
those of poor attention and executive function in comparison with the healthy group;
while in the bipolar group, executive function was the main cognitive impairment in
comparison with the healthy group. Thus assessment for cognitive dysfunction and
measures to alleviate these symptoms should be included in the management of these
patient groups. |
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