Cognitive recovery after stroke

Abstract

Stroke is one of the leading causes of death and long-term disability worldwide. The incidence of ischemic stroke in The Netherlands alone is 35.000 per year, translating to roughly 100 new patients with ischemic stroke every day. Apart from the physical consequences, up to 75% of the patients have cognitive deficits after ischemic stroke. Cognitive deficits after ischemic stroke are independently associated with lower quality of life, poorer functional outcome, and worse community reintegration. Fortunately, roughly half of the patients with cognitive deficits after ischemic stroke show recovery over time. The other half, however, remains cognitively impaired or even deteriorates. Predicting cognitive recovery in patients with a cognitive disorder after ischemic stroke could have important consequences for daily practice: it could help in providing realistic psycho-education for patients and their families, and it could ultimately help in matching the goals in rehabilitation programs to the patient’s potential for recovery. However, prediction of cognitive recovery after ischemic stroke on clinical features alone is still inaccurate. Measures of brain connectivity have emerged in the literature as important markers of various types of brain injury that are relevant for cognition, and may add value to conventional predictors in predicting cognitive recovery after stroke. When looking more specifically at the cognitive deficits that are often seen after ischemic stroke, these can involve the ‘traditional’ cognitive domains memory, executive functioning, visuospatial functioning, language, and attention and processing speed. Another cognitive domain, social cognition, has been studied less frequently following stroke. Social cognition involves the psychological processes by which one perceives, processes and interprets social information, and it involves adequately responding to this social information. There is emerging evidence that ischemic stroke is also associated with deficits in social cognition. In the work described in this thesis we assessed 1) whether measures derived from the structural brain network predict cognitive recovery after ischemic stroke and 2) how often impairments in social cognition occur after ischemic stroke, and more precisely, emotion recognition. This thesis described the development of the lesion impact score, a score that combines information on lesion size with network topology, which was an independent predictor of cognitive recovery after ischemic stroke. By contrast, we could not show there was additional value of more global brain connectivity measures in predicting cognitive recovery over other conventional predictors. We conclude that measures of brain connectivity do not appear to be ready for implementation in daily practice yet, although our findings do show promise. However, further research is needed to assess how these measures can add value in daily practice. In this thesis we also showed that emotion recognition is impaired in one out of three patients, while it is often not recognized by the clinician or the patient. Clinicians should be aware that these impairments occur often and should routinely inform patients about changes in social behavior. If there are signs of changes in a patient’s social behavior or empathy, patients or their caregivers should be provided with psychoeducation and referral to a neuropsychologist should be considered.