Only 14 pages are availabe for public view
Our cross sectional study on 45 prevalent HD patients aimed to evaluate and assess cognitive function globally and selectively, to investigate the possible risk factors of cognitive impairment in HD patients. Intelligence assessment of the studied group was done, which ensured their eligibility to proceed with various cognitive functions tests. We assessed memory in four different specific domains (verbal, working, short term auditory and visual memory), visual attention, and psychomotor speed.
Global cognitive function
Assessment was done by the MMSE which showed that 71.1% (n=32) of studied patients were normal, while 28.9% (n=13) showed mild cognitive impairment (range of score from 30 - 25 is normal, 24-19 is mild, 18-10 is moderate impairment). Global cognitive function of our studied patients was significantly associated with:
• Serum K level (positive correlation was reported), where HD patients with lower serum K level were more impaired than higher one, which confirm the main role of serum potassium level in cognition in HD patients).
• Serum calcium and cholesterol level (negative correlations were reported).
• HCV seropositivity.
Global cognitive function of our studied patients was not significantly associated with age, so that our study reported that age of HD patients had no impact on all cognitive functions measurement.
Our findings reported that HD patients had different levels of memory function decline including working memory (86.7%), short term auditory memory (80%), visual memory (73.2%), verbal memory as regard immediate recall (42.2%) and delayed recall (48.9%).
Working memory was the most affected cognitive function in our studied patients (86.7%), since HD patients get a large amount of education on their diet, medications and treatment. If they have problems in their ability to retain such information through their working memory, they won’t understand sentences given to them and hence won’t perform instructions given to them whether during their dialysis session or after it, which might lead to detrimental consequences.
The low compliance commonly observed in HD patients may be, at least partially, attributed to receiving instruction during treatment, a time when cognitive functions such as working memory and executive function are impaired, so current practice in Nephrology includes counseling patients during MHD treatment may not be the best course of action.
Our study revealed that there is a statistically significant difference between patients with normal and impaired working memory regarding CRP titer (significantly higher in patient with impaired working memory), Conforming with the evidence that has linked inflammation to cognitive decline in HD patients, Also working memory was significantly positive correlated with PTH level (PTH is significantly lower in patients with impaired working memory than normal one).
Verbal and visual memory showed a significant association with gender where females were more impaired than males, also both functions reported a positive correlation with serum k level (serum K is significantly lower in patients with impaired verbal and visual memory than normal one)
Our study revealed that there is a significant difference between patients with normal and impaired short term auditory memory as regard predialysis urea (P=0.026), CRP (P=0.05), AST (P=0.005) (higher in patients with impaired short term auditory memory), also significant difference regarding PTH (P=0.036) was reported (as PTH was lower in patients with impaired function).
The group of patients with impaired visual attention showed a statistically significant difference as regard BMI, serum cholesterol, triglyceride (significantly higher in patient with impaired visual attention) and HDL (significantly lower in patient with impaired visual attention).
The percentage of patients with impaired psychomotor speed in our sample (26%) was lower than other previous studies. Our study showed no statistically significant correlation between psychomotor speed and demographic, studied clinical and laboratory data.
Atherosclerosis was reflected by Carotid intimal media thickness which was measured among studied patients by carotid Doppler. Mean of CIMT was 0.90 ± 0.19 mm with range from 0.5 to 1.14 mm. Our study showed a statistically significant negative correlation between atherosclerosis and visual memory, with no other significant correlation with other different cognitive functions. These data support that cognitive impairment in HD patients was independent of atherosclerosis.
Finally, these findings have an important implication in clarifying the mechanisms that may be contributing to cognitive deficits in HD patients. Current findings also illustrate the importance of using measures that incorporate the assessment of selective cognitive functions in HD patients. This study is a stepping stone for future studies that will use more participants to hopefully show an even larger impact on cognition in HD patients.