Background and purpose: Vascular dementia accounts for 40-50% of dementia cases in Singapore. The aim of this study is to examine the prevalence and natural history of cognitive impairment in a cohort of Singaporean post-stroke patients.
Methods: The Vascular Dementia Battery (VDB) was offered to 252 patients with a transient ischaemic attack (TIA) or non-disabling ischaemic stroke at baseline (within 6 months post index stroke) and annually thereafter. The VDB assesses six cognitive domains: attention, language, verbal memory (recall and recognition), visual memory (recall and recognition), visuoconstruction and visuomotor speed. Dementia was diagnosed using the DSM-IV criteria. Patients who did not meet the DSM-IV criteria but were impaired in one or more cognitive domains were classified as 'cognitively impaired but not demented'. Those who were unimpaired in all cognitive domains were classified as 'cognitively intact'.
Results: At baseline, 56% of patients were 'cognitively intact', 40% were 'cognitively impaired but not demented' and 4% were 'demented'. At 1-year follow-up, 33% patients had a changed classification from baseline. While 31% of those who were 'cognitively impaired but not demented' at baseline improved to 'cognitively intact', 10% of the 'cognitively intact' group deteriorated to 'cognitively impaired but not demented' and 11% deteriorated from 'cognitively impaired but not demented' to 'demented'. Cognitive performance at baseline predicted for deterioration.
Conclusions: This study suggests that the long-term cognitive performance in stroke patients change over time. Further studies are required to identify risk factors and effective treatment for cognitive deterioration after stroke.