OBJECTIVE: The aim of this study was to describe the association between ischaemic heart disease (IHD), diabetes mellitus (DM) and heart failure (HF) and the prevalence of cognitive impairment. METHODS: In a cross-sectional, community-based study in Karlskrona, Sweden, 1402 participants of the Swedish National Study on Ageing and Care (60-96 y) underwent a medical examination and psychological testing including the Mini Mental State Examination (MMSE). Of these, 58% stated that they were treated for hypertension, IHD, DM or HF, or had ECG abnormalities (positive screen). RESULTS: The prevalence of cognitive impairment (MMSE score < 24) in patients treated for IHD, DM or HF was 28.5% compared to 16.1% in the population with a negative screen without cardiovascular disease or DM. After stratification by age, the difference was seen to be due to a higher prevalence of cognitive impairment in the age group 70-79 y, where 68.8% of the cognitively impaired came from the group treated for IHD, DM or HF. The odds ratio for cognitive impairment in this age group was 4.4 (95% CI 1.7-11.4), when compared to those with a negative screen as baseline. CONCLUSION: This study has shown that the patient group treated for IHD, DM or HF has a higher prevalence of cognitive impairment and a higher risk of developing early cognitive impairment between the ages of 70 and 79 y. Although this study has not provided conclusive evidence that cardiovascular disease and DM are associated with the early development of cognitive impairment, it provides incentive for further studies.