The high prevalence of poststroke cognitive impairment has been confirmed by Australian-led research that has also revealed the most common risk factors.
Researchers at the Centre for Healthy Brain Ageing (CHeBA) at University of NSW, Sydney, worked with international collaborators to analyse data from a combined sample of 3,146 participants admitted to hospital for stroke (97%) or TIA (3%).
They found that overall 44% were impaired in global cognition and 30-35% were impaired in individual domains at two to six months after the index event.
Proportions of impairment were significantly greater in left hemisphere stroke compared to right hemisphere stroke in global cognition, memory, language, and executive function.
Impairment was greater in right hemisphere stroke compared to left hemisphere stroke in perceptual motor function, but the statistical significance was borderline.
Patients with stroke related to small vessel disease aetiology had significantly less impairment than patients with other stroke subtypes.
In terms of vascular risk factors, diabetes mellitus was strongly associated with poorer cognitive functions such as attention and processing speed (effect size -0.46); memory (effect size -0.25); language (effect size -0.25); perceptual motor (effect size -0.33); frontal executive function (effect size -0.36) and global cognition (effect size -0.53).
History of stroke was also strongly associated with poorer cognitive functions (effect size for global cognition -0.50).
Other risk factors such as hypertension, smoking, and atrial fibrillation had weaker domain-specific associations.
The research, published in Neurology, harmonised data from 13 international studies as part of the Stroke and Cognition Consortium (STROKOG) led by study co-ordinator Jessica Lo of CHeBA.
“This study is significant for practicing neurologists and clinicians because it presents a comprehensive profile of the cognitive performance of patients after stroke from around the world,” said Ms Lo.
CHeBA Co-Director and co-author, Professor Perminder Sachdev, said that the research warranted attention in the development of prevention strategies.
“This research confirms that, globally, prevalence of impaired cognitive function is consistently high across diverse populations in stroke survivors, with diabetes being an important and independent risk factor for post-stroke cognitive impairment,” he said.