In our ageing population the burden of both heart failure (HF) and dementia is increasing. To date there is no proven preventative or curative treatment for cognitive decline and the associated social and economic cost is huge. Both conditions share common risk factors, yet there is growing evidence of a direct relationship between the function of the heart and the brain. But we still don't know if poor cognition is a consequence or a cause of poorer cardiac function. Several aspects of this association require thorough investigation. We propose that there is a bidirectional association between cognition and cardiovascular disease (CVD) and by applying sophisticated techniques to assess cardiac and brain structure and function, this investigation will significantly advance our understanding of the causal mechanisms underlying both cardiac and cognitive decline.