The association of stroke and dementia is frequent and can be seen either in the diagnostic work-up of patients attending a memory clinic, or during the follow-up of stroke patients. The terms ‘vascular dementia’ (VaD), and ‘poststroke dementia’ (PSD) are respectively used for these two different clinical situations. The term PSD includes any type of dementia occurring after a stroke, irrespective of its presumed cause (Pasquier & Leys, 1997). VaD is a dementia syndrome likely to be due to stroke lesions (Chui et al., 1992; Roman et al., 1993). VaD accounts only for a part of PSD (Tatemichi et al., 1994a, b; Pasquier & Leys, 1997) and may occur without any obvious clinical history of stroke. VaD is the second most common cause of dementia, as it accounts for 10 to 50% of the cases, depending on the geographic location, population and criteria used (Rocca et al., 1991; Hebert & Brayne, 1995). Strokes lead to a high risk of cognitive impairment and dementia (Tatemichi et al., 1992; Tatemichi et al., 1994). As vascular causes of cognitive impairment are common, and perhaps preventable, patients could benefit from therapy, early detection and accurate diagnosis of vascular cognitive impairment and VaD is a challenge (Bowler & Hachinski, 1995).
Epidemiology of poststroke dementia
Depending upon the composition of cohorts, prevalence rates of PSD vary between 13.6% (Censori et al., 1996) and 31.8% (Pohjasvaara et al., 1997) at 3 months. A study reported a prevalence rate of 32.0% after 5 years (Bornstein et al., 1996). The prevalence of dementia is higher in stroke survivors than in matched controls (Censori et al., 1996; Pohjasvaara et al., 1997).