Effects of pioglitazone on cognitive function in patients with a recent ischaemic stroke or TIA: a report from the IRIS trial

INTRODUCTION: Patients with cerebrovascular disease are at increased risk for cognitive dysfunction. Modification of vascular risk factors, including insulin resistance, could improve poststroke cognitive function. METHODS: In the Insulin Resistance Intervention after Stroke (IRIS) trial, patients with a recent ischaemic stroke or transient ischaemic attack (TIA) were randomised to pioglitazone (target 45 mg daily) or placebo. All patients were insulin resistant based on a Homeostasis Model Assessment-Insulin Resistance score >3.0. For this preplanned analysis of cognitive function, we examined the Modified Mini-Mental State Examination (3MS) score (maximum score, 100) during follow-up. Patients were tested at baseline and annually for up to 5 years. Longitudinal mixed model methods were used to compare changes in the 3MS over time. RESULTS: Of the 3876 IRIS participants, 3398 had a 3MS score at baseline and at least once during follow-up and were included in the analysis. Median 3MS score at baseline was 97 (IQR 93-99). The average overall least squared mean 3MS score increased by 0.27 in the pioglitazone group and by 0.29 in the placebo group (mean difference between treatment groups -0.02; 95% CI -0.33 to 0.28, p=0.88). CONCLUSIONS: Among insulin-resistant patients with a recent ischaemic stroke or TIA, pioglitazone did not affect cognitive function, as measured by the 3MS, over 5 years. TRIAL REGISTRATION: ClinicalTrials.gov NCT00091949; Results.