The relationship of cognitive impairment in multiple sclerosis patients with neurological and psychiatric variables

Cognitive impairment (CI) is an important feature of multiple sclerosis that affects upto 50% of patients. It can develop at any time during the course of the disease and it can even be the first symptom of the illesss. Severity of cognitive dysfunction seems to be primarily associated with the degree of specific neuronal loss but factors like disease progression, duration of disease, fatigue, comorbid affective disorder or drug side effects may also affect cognitive function.We aimed to assess cognitive function in MS patients and demographically matched healthy controls and to see if there is a difference between these two groups and if there was a difference to see which cognitive areas were affected more in the patient group.We included 31 MS patients diagnosed according to McDonald criteria from the Department of Neurology in Abant Izzet Baysal University and compared them with 31 healthy controls matched for age, sex and education. The neurological evaluation and The Expanded Disability Status Scale (EDSS) scoring was first made by a neurologist and then the investigator performed the standardized psychiatric evaluation with SCID-I and applied Standardized Mini Mental Test to both patients and healthy controls. Then both groups were evaluated for depression and anxiety with Hamillton Depression Scale (HAM-D) and Anxiety Severity Scale (HAM-A), functioning was evalutated by Global Assesment of Funcitonallity Scale, fatigue was assesed by self rating Fatigue Severity Scale and a set of cognitive functions were assesed by Serial Digit Learning Test, Verbal and Nonverbal Cancellation Test, Stroop Test and Rey Auditory Verbal Learning Test.We found no difference in terms of sociodemographic variables between patients and healthy controls except for working status. The percentage of jobless people were higher in the patient group compared to controls. Also, psychiatric comorbidity, especially depressive and anxiety disorders, were higher among MS patients. As for the cognitive tests, retrieval from long term memory and psychomotor speed were signiticantly worse in the MS group compared to healthy controls. Cognitive impairment showed a positive correlation with duration of disease, number of attacks and physical disability though there were no correlation between cognitive impairment and depression/anxiety severity. The duration of disease predicted disturbances in recall and psychomotor speed whereas severity of fatigue and disablity predicted depression.As a result, we found that psychomotor speed, attention and memory were primarily imparied in MS patients and these cognitive impairments were closely associated with clinical aspects of MS like number of attacks, level of disability and especially with duration of disease. This cognitive impairment seen in a patient population with mild degree of disability and a relatively short duration of disease indşcates that cognitive impairment can be seen even in early stages of disease before advanced neurological dysfunction sets in.Progression of cognitive impairment can predict progression of disease without an increase in physical disability. Because of that, objective evaluation of cognitive function in MS can be a precious alternative marker of disease progression. Also, cognitive impariment can decrease patients quality of life and increase their family?s burden by negatively affecting them. So, cognitive evaluation should be a routine part of neurological examination and in order to do this short, sensitive, simple, easy to use, cost-effective cognitive tests should be developed.