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BACKGROUND:

The presence of cognitive impairment following stroke onset strongly indicates poor prognosis of the patients surviving the crisis.Understanding of the incidence of cognitive impairment after ischemic stroke and its confidence interval has practical significance in preventing is occurrence in stroke patients and its differentiation from age-related cognitive impairment.

OBJECTIVE:

To study the incidence of cognitive impairment in patients with the first onset of ischemic stroke.

DESIGN:

Single-factor analyses of the cases followed up for 3 months

SETTING:

Research Institute of Surgery, Daping Hospital, Third Military Medical University of Chinese PLA.PARTICTPANTS Totally 434 inpatients with acute cerebral infarction [218 male and 216 female, aged 55 to 85 with a mean of (70.3±9.5) years]admitted within 48 hours after the onset in Department of Neurology, Daping Hospital of Third Military Medical University from May 8, 1999 to December 31, 2000. All patients participated in this study voluntarily.

METHODS:

The general background and clinical data of the patients were collected at the time of admission. A simplified intelligence test was performed both 7 to 10 days of the onset and 3 months after discharge. The scale employed for the test included 20 questions with a total of 30 items divided to test 5 aspects of the patients' cognition, namely orientation ability, memory, calculation ability, memory recall and linguistic ability (1 point was given for a correct answer, and 0 for an wrong one or an answer of "I don't know", with the total score of 30 for all items). A score of the simplified intelligence test less than the score of demarcation (specifically,below 17 for illiterate patients, below 20 for those receiving an education no more than 6 years, and below 24 for those having an education for no less than 7 years) for 3 months after cerebral stroke was regarded as the diagnostic criteria for cognitive impairment.MAIN OUTCOME

MEASURES:

The incidence of cognitive impairment was recorded 3 months after hospital discharge and single-factor analysis of the scores of simple intelligence test.

RESULTS:

All the 434 patients were included in result analysis. Totally 161 (37.1%) patients were diagnosed as having cognitive impairment, and 273 (62.9%) had normal cognitive function 3 months after hospital discharge. The mean age of the patients with cognitive impairment was significantly higher than that of the patients with normal cognitive function [(73.0±7.0) years vs (64.5±6.6) years, t=2.626, P ＜ 0.01]. The proportion of patients with cognitive impairment receiving education for no more than 6 years was significantly higher than that among patients with normal cognition (45.3% vs 22.7%, OR=2.823, with 95% confidence interval of 1.855 -4.297), and the score of simple intelligence test was significantly lower in the former patient group (16.3±8.7 vs 23.4±4.2, t=3.352, P ＜ 0.001).

CONCLUSION:

The incidence of cognitive impairment in this cohort is relatively high. The patients with cognitive impairment following cerebral infarction have obviously older age and poorer education, suggesting significant synergetic effect of age and education with cognitive impairment following cerebral infarction.