The effects of blood pressure on post stroke cognitive impairment: BP and PSCI

Abstract Cognitive function following acute ischemic stroke (AIS) is critical to prognosis and quality of life. Hypertension is a risk factor for stroke and is associated with post stroke cognitive impairment (PSCI). However, the optimal blood pressure parameters after AIS is unknown. This is a sub‐study of the Impairment of CognitiON and Sleep after acute ischemic stroke or transient ischemic attack in Chinese patients (ICONS) study conducted between August 2015 and March 2018. Cognition was assessed at two‐week (2w), three‐month (3 m), and twelve‐month (12 m) by Montreal Cognitive Assessment (MoCA). A total of 682 participants who met the inclusion criteria were enrolled. The primary outcome was cognitive changes after 3 and 12 months post stroke. Among 682 participants, the mean age was 59.35 ± 10.40 years and 72.29% were men. PSCI patients with high systolic blood pressure (SBP ≥140 mm Hg) at 3 m not only had worse cognition as evidenced by MoCA scores at 3 m but also predicted worse scores at 12 m. When participants were stratified into cognitively stable/improved (MoCA score ≥0, 2w vs. 12 m) and cognitively impaired (MoCA score ≤‐2, 2w vs. 12 m), those with high SBP were more likely to be cognitively impaired (OR 2.17, 95%CI 1.12–4.21, p < .05) and less likely to be cognitively stable/improved (OR 0.66, 95%CI 0.44–0.99, p < .05). SBP more than 140 mm Hg is associated with worse cognitive performance after ischemic stroke. Patients with SBP lower than 140 mm Hg have better cognitive outcome at 3‐month and 1 year after stroke.

compromised stroke patients with less cerebral plasticity requires further investigation. In this pre-specified sub-study of the Impairment of Cognition and Sleep after acute ischemic stroke (ICONS) study, we examined what blood pressure parameters are beneficial to these at risk patients who had cognitive deficits after stroke.

Study design and participants
We used the database of the ICONS study which was conducted at 40 clinical centers in China from August 2015 to April 2018. 12 In this sub-study, patients were selected who were within 7 days of confirmed Ltd.) was at the heart level. Measurements were taken two times consecutively on the non-dominant arm, with 1-min interval. Blood pressure was recorded as the average of the two measurements. Medications and other medical information were recorded. 12 The trial was approved by the ethics committee of each medical institution. Written informed consent was obtained from all participants or their legal guardians.
According to 2020 International Society of Hypertension Global Hypertension Practice Guideline, 13

Outcomes
The safety outcomes in this analysis were similar to those of the ICONS study. The primary efficacy outcome was cognitive decline or improvement at 3 m and 12 m visits compared to the 2w visit, as well as the MoCA scores at 3 m and 12 m visits. MoCA is widely used and has been validated as efficacious in post stroke assessment of cognition due to its sensitivity and specificity in determining mild cognitive impairment (MCI). 14 Cognitive decline is defined as a reduction in MoCA score of two or more points (one standard deviation, SD), 15,16 and cognitive improvement as an increase of two or more points.

Statistical analysis
We presented continuous variables as mean ± SD or median with

RESULTS
A total of 682 participants were enrolled in this study. MoCA scores (p < .0001). They were also older and had worse scores of mRS. In terms of DBP, high DBP at 3 m was associated with high BMI and high incidence of bleeding after admission, but not with cognitive performance (Table S1). DBP at 12 m had no correlation with stroke or cognitive function (Table S2).
To further validate the relationship between different SBP and cognition, we divided participants into the cognitively stable/improved and cognitive impaired groups based on their MoCA scores at 12 m compared to 2w. The cognitively stable/improved group was younger, less likely to have a history of hypertension. The cognitively impaired group was more likely to have previous strokes and an undetermined cause of TOAST type, recurrent AIS and worse mRS scores (Table 3). Recurrent AIS obviously influence the results, after removing them, 632 participants were analyzed in logistic regression of different models, when age, sex, and education were taken into consideration, participants with high SBP were more likely to be cognitively impaired (

DISCUSSION
In this study, we have demonstrated the benefits of hypertension control on cognitive performance, when controlled for all other parame-   18,19 Therefore, there is considerable controversy regarding ideal post stroke blood pressure parameters especially in vulnerable patients with cognitive deficits after stroke. 8,9 There is no correlation between DBP and cognitive performance.
SBP is considered a stronger predictor of blood pressure related outcomes than DBP. 20  However, after excluding the effects of recurrent AIS, SBP still has significant impact on cognitive performance (Table 4, model 3).
There are several limitations of the study. First, this is a prospective observational study. Age, sex, and education levels were not tightly controlled for study groups. Since all of them can affect cognition, we used logistic regression analysis (model 1) to discount their effects.
Second, blood pressure is likely to fluctuate in the period of 1 year. It has been shown that the fluctuations in blood pressure have predictive values in patients with stroke, a potential risk factor for cognitive decline in dementia. We tried to limit this fluctuation by multiple analysis at 3 m and 12 m. The results from these two time points are con-