الفهرس 
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Abstract
The clinical manifestations of MDD are not limited to mood symptoms, but also include a range of cognitive and somatic symptoms. Thus, MDD is considered a multifactorial disorder which varies in terms of symptom severity, psychiatric co-morbidity, and clinical course, including recurrence and response to treatment (Seok et al., 2012).
Recent evidence suggests that cognitive impairment in MDD is a key factor of an individuals’ functional outcome. Difficulties in functioning socially are also linked to cognitive dysfunction in depression (Withall, Harris, & Cumming, 2009).
It persists even after depressive symptoms remiss (Hasselbalch et al., 2011), and worsens with recurrent depressive episodes (Gorwood et al., 2008). Even after mood symptoms subside, baseline daily functioning levels are not always restored. Furthermore, it has been suggested that cognitive remission should be the therapeutic aim to restore full functioning and prevent relapse (Bortolato et al, 2016).
In the last years, cognitive impairment in depression has been widely reported. It is clear that cognitive symptoms persist after remission of psychopathological symptoms but little is known about the pathophysiologic events linking depression and cognitive impairment. Novel biological, structural and functional Neuro imaging techniques have allowed a better definition of this relation. Depression and cognitive dysfunction share a common Neuro pathological platform in cortical and sub-cortical brain areas implicated in emotional and cognitive processing which may be under the control of genetic and environmental factors (Lam et al., 2014).
This thesis was designed aiming at covering the following areas in the theoretical part:
1. An overview of major depressive disorder and its effect on Cognitive Function during the euthymic state of the disease.
2. Review of cognitive functions in First and Recurrent episodes of MDD.
3. Review of the management strategies of cognitive dysfunction associated with major depression.
The practical part aimed at:
1. Assessing the cognitive performance among Egyptian patients with Major Depressive Disorder in their Euthymic state.
2. Cognitive Differences found between patients suffering from First and Recurrent Depressive Episodes.
We hypothesized that euthymic major depressive disorder patients show a poorer performance in tasks of intelligence, executive function and memory compared to their control group. We also hypothesized that differences in cognitive performance in euthymic patients with major depression between primary and recurrent episodes might exist. We attempted to ascertain whether specific cognitive deficits could be observed in euthymic patients and whether they showed different patterns of performance, and also the role of different factors correlated with neuropsychological performance.
The present study evaluated collectively 60 euthymic patients with MDD who were equally divided into FED and RED and one CG composing of 35 healthy subjects. The study was carried out at the outpatient department of the institute of psychiatry, Ain Shams University.
We obtained an informed consent. Inclusion criteria was ensured before the study was conducted; which included age between 18-45 years, Egyptian male and female subjects, MDD subjects in euthymic state.
The tools were precisely selected to fulfil the purpose of the study; they included the Hamilton Rating Scale for Depression, Wechsler adult intelligence scale (WAIS), Wechsler memory scale (WMS), Wisconsin card sorting test (WCST) and Global Assessment Scale (GAS).
All data gathered was recorded, tabulated and transferred on a Statistical Package for Social Sciences (SPSS) using a personal computer and the suitable statistical parameters. Results were displayed to answer questions raised in the hypothesis of the study.
On Demographic characteristics, the patient groups and the control group were matched for age, gender, years of education, social class, marital status and occupation. There was a significant difference between marital status, occupation, between FED and RED and the CG.
On Clinical characteristics:
Our study demonstrated statistically significant differences between FED and RED as regards Family History of Depression, types of anti-depressants, medication compliance, childhood abuse, duration of illness, ECT and Global Assessment of Function.
On Tests of General Intelligence:
On all domains of Wechsler Adult Intelligence Scale (WAIS), the CG had a significantly higher mean score than both FED and RED. Tukey’s post-hoc test analysed these domains in further details. CG had superior scores compared to FED in the following domains; Verbal IQ, Performance IQ, Total IQ, Verbal Comprehension, Verbal Arithmetic, Verbal Digit Span, Verbal Similarities, Performance picture completion, Performance Block Design and Performance Digit Symbol.
CG also had superior scores compared to RED in the following domains: Verbal IQ, Performance IQ, Total IQ, Verbal Arithmetic, Verbal Digit Span, Verbal Similarities, Performance Picture Completion, Performance Block Design, Performance Digit symbol and Verbal Comprehension.
Meanwhile, the group representing FED has significantly higher scores compared to RED in only a few domains; Verbal Digit Span and Verbal Similarities.
On Tests of Memory:
In Wechsler Memory Scale (WMS), the control group showed significantly higher scores compared to both groups in the following domains; Verbal PA2, Visual PA2 and Visual Memory-Backward.
Tukey’s Post hoc test revealed a significant difference between CG compared to both FED and RED in the following domains; WMS Information, Verbal PA2, Visual PA2 and Digit Span Forward.
Scores of CG showed a significant difference compared to only FED in the following domains; Digit Span Backwards and Visual PA1.
CG showed a significant difference to only RED in only Visual Memory Backwards.
Patients suffering from a single episode of MDD showed higher scores compared to patients who witnessed recurrent episodes of MDD in the following domains; Digit Span (Forward and Backward score), Verbal PA1 and Visual PA1.
On Tests of Executive Functions:
In Wisconsin Card Sorting Test (WCST), the CG showed superior scores compared to both FED and RED in the following domains: Trials Administered, Total Correct Responses, Total Error, Percent of Error, Preservative Responses, Percent of Preservative Responses, Percent of Preservative Errors, Percent of Non-Preservative Errors, Conceptual Level Responses, Percent of Conceptual Level Responses, Categories Completed, and Learning to Learn.
Tukey’s Post-hoc test revealed a significant difference between CG compared to FED in the following domains; Trials Administered, Total Correct Responses, Preservative Responses, Percent of Preservative Responses, Percent of Non-Preservative Errors, Conceptual Level Responses, Categories Completed all at P value (p < 0.001) and Failure to Maintain Set. Tukey’s Post-hoc test also revealed a significant difference between CG compared to RED in the following domains; Trials Administered, Total Correct Responses, Percent of Error, Preservative Responses, Preservative Error, Percent of Non-Preservative Errors, Conceptual Level Responses, Percent of Conceptual Level Responses and Categories Completed.
Finally, Tukey’s Post-hoc test revealed a significant difference between FED and RED, showing higher scores in FED in the following domains: Total Correct Responses, Percent of Non-Preservative Errors), Conceptual Level Responses, Percent of Conceptual Level Responses and Failure to Maintain Set and showing lower scores in FED in the following domains: Preservative Responses, Percent of Preservative Responses, Preservative Errors and Percent of Preservative Errors.
So far, there is no clear evidence on whether or not there are any differences in cognitive performance among euthymic patients with FED and RED. Our study is considered as the first study to address this issue in an Egyptian sample. We hope that this work will have contributed to the growing knowledge in this area.
Our clinical recommendations included routine assessment of cognitive functions in outpatient clinic throughout the management of MDD, better screening for cognitive deficits in patients with mental illnesses, family counselling about the hazards of cognitive impairment in patients with mental illnesses, developing strategies for cognitive enhancement and rehabilitation and considering the impact of cognitive side effects of medications when prescribing them to patients. Our research recommendations included conducting epidemiologic surveys on large scales to assess cognitive dysfunction in Egyptian patients with MDD, considering repeated assessment of cognitive functions in clinical trials on antidepressants as a measure of improving quality of life in MDD patients and studying cognitive dysfunction in other subtypes of depression such as adolescents, late life depression and depression with psychotic features.