Poststroke dementia: incidence and relationship to prestroke cognitive decline

To evaluate the 3-year incidence of poststroke dementia (PSD) and the influence of prestroke cognitive decline.

The authors evaluated prestroke cognitive functions in 202 consecutive stroke patients > or =40 years old using the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE), with a cut-off of 104 for the diagnosis of dementia. Six months and then annually after stroke, dementia was reassessed. The diagnosis of dementia was based on the International Classification of Diseases, 10th revision criteria in survivors who underwent a visit with a neurologist, or on the IQCODE score obtained by telephone contact with the family in survivors who did not. Statistics were performed using life-table methods.

Thirty-three patients were excluded because of prestroke dementia. In the 169 remaining patients, the cumulative proportion of patients with dementia was 28.5% at the end of the follow-up period, with most of PSD occurring during the first 6 months. Using multivariate analysis, independent predictors of PSD were aging, preexisting cognitive decline, severity of deficit at admission, diabetes mellitus, and silent infarcts. Leukoaraiosis was an independent predictor of PSD when prestroke cognitive decline was not taken into account. The presumed etiology of dementia was vascular dementia (VaD) in two-thirds of patients and AD in one-third.

The risk of PSD is high, and increased in patients with prestroke cognitive decline, with about one-third of patients meeting the criteria for AD and two-thirds meeting the criteria for VaD. These results confirm that, in stroke patients, an underlying degenerative pathology may play a role in the development of PSD.