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The neurobehavioral syndrome of uremia in chronic kidney disease affects the functioning of the central nervous system. Cognitive impairment is one of the most important manifestations of this dysfunction. The process of hemodialysis is known to bring about conflicting changes in the cognitive status of patients. In the present study an assessment of cognitive status of patients with end stage renal disease was done in comparison to controls before and after a session of hemodialysis using simple bedside paper-pencil tests. Thirty patients of end stage renal disease on maintenance dialysis for at least one month with MMSE score >24 were assessed one hour before and one hour after hemodialysis using Digit Symbol Substitution Test, One Letter and Three Letter Cancellations tasks. Their results were compared to age and sex matched healthy controls. The patients with end stage renal disease had significantly lower performance in cognitive tests in comparison to controls. The performance improved 1 hour after hemodialysis in comparison to pre-dialysis values. However, the values after dialysis were significantly lower than in controls, thereby indicating that though the cognitive functions improved after hemodialysis, they did not reach the control levels. There was also a significant change in the biochemical parameters after dialysis. We conclude that patients with end stage renal disease suffered from cognitive impairment which improved on hemodialysis due to removal of metabolic waste products.

Caffeine is one of the most widely consumed stimulant drugs of the modern world. It brings about a feeling of well-being, relaxation, increased alertness and concentration. Its effects have been studied on brain function and behavior using mood questionnaires, reaction time tests, memory tests, EEG and of late Event Related Potentials (ERPs). This study evaluates the response of caffeine on ERPs and Reaction Time (RT) using auditory "oddball" paradigm. Forty undergraduate medical students volunteered for the study and their ERPs and RT were recorded before and after 40 minutes of ingestion of caffeine. There was a non-significant decrease in latency of N1, P2, N2 and P3 and a significant decrease in Reaction Time after caffeine consumption. The amplitude of P3 showed a significant increase after intake of caffeine. The results of this study indicate that caffeine leads to facilitation of information processing and motor output response of the brain.

Background: Very less work has been done in the past to assess cognition in hypothyroid patients using classical color-word Stroop task. The Stroop color-word task is a well-recognized tool which estimates cognitive inhibition. Stroop task is based on the fact that reading words and identifying color of written words are two different information and they process with a common response channel but with different speeds. The aim of this study was to assess the cognitive inhibition process in drug-naïve hypothyroid patients and their comparison with the same patients after the attainment of euthyroid status and also with euthyroid controls using classical color-word Stroop task. Materials and Methods: Thirty drug-naïve newly diagnosed hypothyroid patients were study cases who underwent Stroop task once before initiating treatment and then after the attainment of euthyroid state. We performed the same test in euthyroid controls twice at an interval of 3 months for comparison purpose. Correlation analysis was also done for hypothyroidism and cognition. Results: The reaction time of Stroop task was decreased in all the three conditions of each block, i.e., neutral, incongruent, and congruent conditions after the attainment of euthyroid state, and the finding confirms posttreatment modulation of the attention processes in hypothyroid patients. Reaction time of Stroop task in hypothyroid patients was positively correlated with the serum thyroid-stimulating hormone levels. Processing of color identification was suppressed than reading words in hypothyroid patients as evidenced by increased reaction time of Stroop task. This increase in reaction time can be reversed by earlier identification of drug-naïve hypothyroid cases so that they can get timely treatment to restore their cognitive status. Conclusions: Stroop task scores are reduced in overt hypothyroid patients, but improve after thyroid replacement therapy. [ABSTRACT FROM AUTHOR]

Background: Sleep is an important factor affecting cognitive performance. Sleep deprivation results in fatigue, lack of concentration, confusion and sleepiness along with anxiety, depression and irritability. Sleep deprivation can have serious consequences in professions like armed forces and medicine where quick decisions and actions need to be taken. Color-Word Stroop task is one of the reliable tests to assess attention and it analyzes the processing of information in two dimensions i.e., reading of words and naming of colour. The evidence regarding the effect of sleep deprivation on Stroop interference is conflicting. The present study evaluated the effect of 24 hours of sleep deprivation on reaction time and interference in Stroop task. Materials and Methods: The present study was done on 30 healthy male medical student volunteers in the age group of 18-25 years after taking their consent and clearance from Institute Ethics Committee. Recordings of Stroop task were at three times: baseline (between 7-9 am), after 12 hours (7-9 pm) and after 24 hours (7-9 am, next day). The subjects were allowed to perform normal daily activities. Results: The study revealed a significant increase in reaction time after 24 hours of sleep deprivation in comparison to baseline and after 12 hours of sleep deprivation. There was no significant change in interference and facilitation after sleep deprivation in comparison to baseline. The number of errors also did not show any significant change after sleep deprivation. Conclusion: The study indicated that there was slowing of responses without change in executive functions after 24 hours of sleep deprivation. It is probable that 24 hours of sleep deprivation does not bring about change in areas of brain affecting executive functions in healthy individuals who have normal sleep cycle. The present study indicated that in professions like armed forces and medicine working 24 hours at a stretch can lead to decrease in motor responses without affecting information processing and judgment ability. [ABSTRACT FROM AUTHOR]