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What is impact?
  1. Matthew C Kiernan
  1. Correspondence to Professor M C Kiernan, Editor-in-Chief of JNNP, Neuroscience Research Australia, Barker Street, Randwick, Sydney, NSW 2031, Australia; m.kiernan{at}

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The word ‘impact’ is in peril of becoming hackneyed terminology. In modern parlance its meaning appears to have undergone more costume changes than Lady Gaga on a whistle-stop tour! And in the world of medical publishing the definition of ‘impact’ is nowhere more nebulous than where a ground breaking paper, and a review that merely cites a ground breaking paper, are measured using the same impact criteria.

How then does one judge the impact of a publication, both at the time and thereafter? For instance, in high turnover publications such as daily newspapers, initial impact may be phenomenal, although transitory, from front page scoop, to fish and chips wrapping in the space of a single day. When considering medicine, and particularly medical publications, presumably the desired impact would mean that manuscripts were read, information conveyed and subsequently adopted by the reader, and as a consequence, practice was changed with the reasonable hope and anticipation that patient outcomes would improve.

When considering the role of JNNP in such a process, in addition to immediate impact, the journal's current high standing has been built up over close to a century of publishing the world's seminal neuroscience publications.1 As proof of longevity and ongoing relevance, akin to opening bottles of wine from an established cellar for the palate of the connoisseur, the success of the journal's immense archive built up from 1920 is reflected through our achievement of the longest citation half-life of any journal across the clinical neurosciences. In other words, the original JNNP manuscripts continue to be heavily cited, many in the thousands,2 3 with some notching up more than 10 000 citations,4 further serving to reinforce the journal's standing as a neuroscience trailblazer.

How then does a manuscript become highly cited, a critical work from which others model and further develop their theories and practice? To help us understand the process, in this issue of JNNP we launch Impact Commentaries (figure 1), a monthly series which will provide a modern perspective on some of the most highly cited JNNP papers of all time. Where possible, we have approached the authors of the original study. In those instances where the author is no longer alive, we have asked key opinion leaders to comment on the original science and subsequent course of the findings presented, to decipher the reasons behind the success of each publication. In addition to providing pearls of wisdom, these commentaries provide newcomers, such as neurology trainees, with an opportunity to put the discoveries and developments into an historical context. Unfortunately, it is all too rare to have the opportunity to get the ‘long view’ from the original author of research that in retrospect has been a blockbuster. With our new monthly Impact Commentaries, we will focus on the opinions that set the scene and then go beyond the research study to discover how it influenced important developments in the field, in some cases over many decades—a perspective that newcomer journals are unable to provide.

Figure 1

Impact Commentaries, launched in this month's issue, provide a modern perspective on the most highly cited JNNP papers of all time.

While looking at impact from the past, JNNP continues to be excited about the future. Our ultimate goal is to identify key new developments and potential future discoveries in the constantly evolving world of neuroscience. The past year has seen JNNP receive more than 3000 submissions, although the higher submission rates inevitably generate greater selectivity. Already, a significant proportion of these recently published manuscripts, covering the entire realm of clinical neuroscience, are well on the way to becoming citation classics in their own right.5–16 Add to this reviews from experienced clinician researchers, regular podcasts and the recently launched JNNP blog, and a very 21st century notion of ‘impact’ begins to develop.

Borrowing a sentiment from the musician Brian Eno, once you've shocked, you can't shock again with the same tune. This year at JNNP we will be embracing that old rocker's conviction by both examining why the papers that shaped the world of neuroscience did so and seeking out the future classics that will make their ‘impact’ on the brain and mind sciences. We look forward to an exciting and challenging year ahead.



  • Competing interests None.

  • Provenance and peer review Commissioned; not externally peer reviewed.