The effects of short-term blood pressure variability and nighttime blood pressure levels on cognitive function

We investigated the relationship between 24-h blood pressure (BP) and cogni tive function. We performed the Hasegawa Dementia Scale Revised(HDSR), the Mini-Mental State Examination(MMSE), and the Raven's coloured Progressive M atrices Test (RCPM) in 88 subjects (71+/-9 years) with no history of stroke . Ambulatory BP was non-invasively measured using a TM2421 for 24 h in all patients. Whereas 90% of the scores converged into a narrow range between 2 5 and 30 points in the HDSR and the MMSE tests, the RCPM score was widely d istributed, ranging from 9 to 36 points. The subjects were therefore divide d into three groups of greater than or equal to 25, 26-30, and 31-36 accord ing to their RCPM scores. Subjects with lower scores were significantly ass ociated with increased short-term BP variability during the daytime (p<0.05 ) and had a tendency toward higher nighttime SEP (p=0.05) compared with tho se with higher scores. Increased shortterm variability of daytime BP and hi gh nighttime systolic BP were associated with cognitive impairment as asses sed by the RCPM, The RCPM, which can assess the capacity for judgment throu gh visual information processing, may detect earlier stages of cognitive im pairment related to high BP, To prevent a deterioration of cognitive functi on, strict control of nighttime BP and suppression of short-term BP variabi lity are thus necessary.