Blockchain is a novel technology capturing the attention of Central Banks and a technology with significant disruptive potential. However, a gap in research effort between practitioners and academics seems to have emerged. This paper analyses and maps that gap by exploring trends in peer-reviewed research contributions through thematic categorisation of academic literature on Distributed Ledger Technology (DLT) use-cases for services, operations and functions performed by central banks. Furthermore, this paper provides summaries of opportunities and challenges for central banks arising from blockchain adaptation to each of those use-cases. To achieve this goal, we utilise a Systematic Mapping Study approach. The paper presents an in-depth assessment of statistical and thematic analysis of research maturity and the types of researchers, with specific emphasis on types of central bank use-cases considered for blockchain adaptation. Our work contributes to an understanding of where the most or least attention is directed, allowing for identification of gaps and opportunities for both academics, practitioners and combinations of each. Results show that the research topic is a comparatively new domain. It confirms the gap between depth and volume of the research provision from industry and academia, with industry leading the trend. Our study also found that the most research-intensive use-cases are those for: 1) Central Bank issued Digital Currency (CBDC), 2) Regulatory Compliance and 3) Payment Clearing and Settlement Systems (PCS) operated by central banks; a comparatively low engagement was found in the areas of 4) Assets Transfer/Ownership and 5) Audit Trail.