BP levels in early ischaemic stroke influence risk of poststroke cognitive impairment
Higher or lower blood pressure (BP) in the early phase of ischaemic stroke is associated with an elevated risk of developing poststroke cognitive impairment (PSCI) at 3 months, as shown in a study. This risk may be attenuated by maintaining systolic and diastolic BP (SBP/DBP) in the levels of 143–158/93–102 mm Hg.
Moreover, stroke subtypes of large artery atherosclerosis (LA) and total anterior circulation infarct (TACI) also contribute to increased PSCI risk.
In the study, 796 patients with acute ischaemic stroke were grouped into SBP and DBP quintiles in the early phase. Cognitive function was evaluated after stroke onset using the Montreal Cognitive Assessment (MoCA).
Multivariate logistic regression models revealed that compared with the middle SBP quintile (Q3, 143–158 mm Hg), the lowest and highest quintiles increased the risk of developing PSCI at 3 months by as much as twofold (Q1, 102–127 mm Hg: odds ratio [OR], 1.83; 95 percent CI, 1.64–2.28; p=0.007; Q5, 171–215 mm Hg: OR, 2.32; 1.74–2.90; p<0.001). [Stroke 2018;49:1610-1617]
A similar pattern of associations was seen in diastolic BP quintiles. The ORs were 1.66 (1.24–2.07) in Q1 (66–82 mm Hg) and 2.40 (1.80–3.01) in Q5 (110–138 mm Hg).
Among cerebral infarction subtypes, both LA and TACI also showed an association with increased risk of PSCI at 3 months (ORs, 1.42 and 1.68, respectively; p=0.031 and p=0.001).
Mostly resulting from the occlusion of middle cerebral artery and anterior cerebral artery, LA and TACI are said to induce large infarcts in frontal, parieto-occipital and temporal areas.
Evidence suggests that instead of the total infarcted volume, infarcted volume in strategic areas, namely cortical limbic and heteromodal association areas, frontal cortex and the white matter, explains much of the damage in cognition after stroke. [Neurobiol Aging 2003;24:213-219]
Cognitive impairment following stroke encompasses a variety of deficits in multiple domains, such as attention, executive functions, memory, language and visuo-perceptual abilities. “Intriguingly, our results showed that the impairments in visuo-executive function, attention and delayed recall were most frequent in patients with ischaemic stroke at 3 months, especially those with the SA [small artery occlusion] subtype,” the authors said.
“We found that … PSCI was elevated after 2 weeks of [stroke] onset, reached its peak at 3 months, and then cognitive function was recovered gradually until 12 months,” they added.
The authors acknowledged several limitations to the study, including a limited sample size and a relatively short follow-up period. Also, the 124 patients who did not complete the MoCA or were lost to follow-up might introduce some selection bias, although there were no significant differences in the distribution of the censored patients among the quintiles.