Cognitive impairment in obesity and association of cognitive impairment with sleep quality and depression

Objective: Obesity has become an importantpublichealth problem withseriouseffects on mortality and morbidity. There has been increasing evidence to support that there may be destructive effects on cognitive functions.In this study, it was aimed to compare individuals with obesity in terms of neurocognitive functions with normal weight controls matched forage, sex and education level.In addition, it was aimed to contribute to the potential mechanisms underlying cognitive disorders in obesity by comparing obese individuals with comorbid depression and obese individuals without depression with healthy controls in terms of cognitive functions. Methods:60 obese patients who referred to Black Sea Technical University Faculty of Medicine Psychiatry Department as outpatient between April 2020 and December 2020, did not hav any psychiatric diagnosis other than depression, accepted the study and met the inclusion criteria were included in the study. With the patients included in the study, age, gender and educational status matched 35 healthy controls who with BMI below 25 kg/m2 and without any diagnosed psychiatric disease were included in the study. Obese patients were divided into two groups as 26 with Major Depressive Disorder and 34 without Major Depressive Disorder. All participants were administered SCID-I (StructuredClinicalInterviewforAxis I Disorders) and Rey Auditory Verbal Learning Test, Stroop Test, and Wisconsin Card Sorting Test to assess their cognitive functions. The clinical interview, SCID-I, HAM-D scale, and neurocognitive tests were administered by the physician conducting the study. All participants were asked to evaluate with the Pitsburg Sleep Quality Index. Results: In our study, each of the groups consisting of obese individuals with depression, obese individuals without depression and healthy individuals were found to be similar to each other in terms of characteristics such as age, education level, and gender. In our study , a significant difference was found between all obese participants and healthy controls in the Wisconsin Card Sorting Test, Stroop Test and Rey Auditory Verbal Learning Test. Obese participants performed worse on the Wisconsin Card Sorting Test, the Stroop Test, and the Rey Auditory Verbal Learning Test compared to healthy controls. When obese individuals with depression and obese individuals without depression were compared with healthy controls, it was observed that obese individuals with depression performed worse in many areas than both obese individuals without depression and healthy controls. No significant difference was found between the control group and the OB group, and between the DOB group and the OB group in terms of WCST Number of Perseverative Responses, Number of Perseverative Errors, Number of Non-Perseverative Errors, Percentage of Conceptual Response and Number of Completed Categories, stroop episode 4 and episode 5 total time, AVLT A1 total correct and AVLT A6 total corrects cores.It was observed that the statistical significance between the groups in this category scores was due to the difference between the control group and the DOB group. Conclusion: Based on the data of this study, it was observed that obese individuals showed deterioration in cognitive function areas such as attention, executive functions, verbal learning and memory. When neurocognitive test performances were evaluated between the obese group with MDD, the obese group without MDD, and the control group, it was observed that obesity generally has an additional negative effect on cognitive tests in the presence of MDD. Especially when the performances of obese individuals with MDD were compared with healthy controls, significant differences were observed in various cognitive tasks, while this difference was generally insignificant when the non-MDD obese group was compared with the control group. It has been observed that depression has a detrimental effect especially on inhibition control, attention and cognitive flexibility tests in obese individuals. Considering that obesity and MDD have cumulative effects on neurocognitive functions, more studies are needed to explain the association of obesity-attributed cognitive dysfunction with sleep disorders, MDD, and related metabolic conditions that often coexist with obesity.