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Abstract The clinical manifestations of MDD are not limited to mood symptoms, but also include a range of cognitive and motor 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). 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 pathophysiological events linking depression and cognitive impairment. Novel biological, structural and functional neuroimaging techniques have allowed a better definition of this relation. Depression and cognitive dysfunction share a common neuropathological 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). Cognitive gender differences are still reported, typically with a life-long advantage for men in tasks assessing visuospatial (Voyer et al., 1995) and mathematical abilities (Halpern et al., 2007), whereas women are often found to outperform men in tasks assessing episodic memory and reading literacy (Pauls et al., 2013). In other cognitive tasks,such as category fluency and vocabulary, gender differences are typically not observed (Capitani et al., 1998). Although biologically based explanations for these differences have been proposed, there are also studies indicating that societal factors influence cognitive gender differences (Miller 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 gender differences in profile of symptoms, (2) Review of cognitive functions and gender differences in cognitive dysfunction in major depressive disorder and (3) Review of the management strategies of cognitive dysfunction associated with major depression in terms of gender difference. The practical part aimed at: 1- Assessing the gender difference in cognitive performance among Egyptian patients with major depressive disorder. 2- Assessing the risk factors related to cognitive dysfunction in Egyptian patients with major depressive disorder. We hypothesized that euthymic major depressive disorder patients show a poorer performance in tasks of executive functioning, attention and memory compared to their control group. We also hypothesized that gender differences in cognitive performance in euthymic patients with major depression might exist. We attempted to ascertain whether specific cognitive deficits could be observed in euthymic patients and whether they showed different patterns of performance depending on their gender, 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 male and female groups and one control group composing of 30 healthy subjects (15 males and 15 females). The study was carried out at the outpatient department of the institute of psychiatry, Ain shams university. We obtained an informed consent and inclusion criteria were insured 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, that included the Structured Clinical Interview for DSM-IV (SCID-I), Hamilton Rating Scale for Depression, Wechsler adult intelligence scale (WAIS), Wechsler memory scale (WMS), Wisconsin card sorting test (WCST) and Trail Making Test (TMT). All data gathered were recorded, tabulated and transferred on Statistical Package for Social Sciences (SPSS) using personal computer and the suitable statistical parameterswere used. Results were displayed to answer questions raised in the hypothesis of this 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 in social class, marital status between male and female subjects with MDD and the control group. On clinical characteristics: Our study demonstrated no statistically significant differences between male and female subjects with MDD as regards age of onset, duration of illness, family history of depression, ECT and number of previous hospitalization. On tests of general intelligence: On all domains of Wechsler Adult Intelligence Scale (WAIS), we found that the control group had a significantly higher mean score than the other groups. We also found that male subjects with MDD scored higher than female subjects with MDD in the following domains of WAIS: Verbal IQ, Performance IQ, Total IQ, verbal comprehension, verbal arithmetic, and verbal similarities. On the other hand, female subjects with MDD scored higher than male subjects with MDD in the following domains of WAIS: Verbal digital span,Performance picture completion, Performance block design, and Performance digital symbol. On tests of memory: On all domains of Wechsler Memory Scale (WMS), control group scored higher than the other groups. Also, male subjects with MDD scored higher than female subjects with MDD on all domains of WMS. On tests of executive functions: In WCST, the control group scored less than the other groups in the following domains: total error, percent of error, non-preservative error, percent of non-preservative error and failure to maintain set. The difference between groups was statistically significant. On the other hand, the control group scored higher than the other groups in those domains: total correct responses, preservative responses, percent of preservative responses, conceptual level responses, percent of conceptual level responses, and categories. The difference between groups was statistically significant. Male subjects with MDD group scored higher than female subjects with MDD in the following domains of WCST: Total correct responses, preservative responses, percent of preservative responses, preservative error, percent of preservative error, conceptual level responses, percent of conceptual level responses, categories completed, trials to complete categories and failure to maintain set. On the other hand, male subjects with MDD scored less than female subjects with MDD in the following domains of WCST: Total error, percent of error, nonpreservative error, percent of non-preservative error. On tests of attention: In TMT, the control group had statistically significant lower mean A-score and lower mean B-score than the other 2 groups than both male and female subjects with MDD groups. Also, Female subjects with MDD scored less than male subjects with MDD in A and B scores. We concluded that patients with major depressive disorder in-between episodes performed poorer than control group on tests of intelligence, memory, executive functions and attention. Also, female subjects with MDD performed even poorly than male subjects with MDD and control group on the same tests. So far, there is no clear evidence on whether or not there are any gender differences in cognitive performance among euthymic patients with major depressive disorder. 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 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 and late life depression and depression with psychotic features. |