Molecular neuroscience at its "high": bibliometric analysis of the most cited papers on endocannabinoid system, cannabis and cannabinoids

Abstract

Background: Cannabis, cannabinoids and endocannabinoids are heavily investigated topics with many articles published every year. We aimed to identify the 100 most cited manuscripts among the vast literature and analyze their contents.

Methods: Web of Science (WoS) Core Collection was searched to identify the 100 most cited relevant manuscripts, which were analyzed with reference to (1) authorship, (2) institution, (3) country, (4) document type, (5) journal, (6) publication year, (7) WoS category, and (8) citation count. Semantic content and citation data of the manuscripts were analyzed with VOSviewer.

Results: The most cited manuscripts were published between 1986 and 2016, with the majority being published in the 2000s (n = 51). The number of citations for the top 100 articles ranged from 469 to 3651, with a median citation count of 635.5. The most prolific authors were Vincenzo Di Marzo (n = 11) and Daniele Piomelli (n = 11). The major contributing countries were USA (n = 49), Italy (n = 22), UK (n = 19), and France (n = 11). The most prolific institutions were University of California (n = 14), National Research Council of Italy (n = 12) and National Institutes of Health USA (n = 12). The manuscripts consisted of original articles (n = 75), reviews (n = 24) and a note (n = 1). The most dominant journal was Nature (n = 15). The major WoS categories associated were Multidisciplinary sciences (n = 31), Neurosciences (n = 20), Pharmacology / Pharmacy (n = 16), and General / Internal Medicine (n = 11).

Conclusions: The top-ranked manuscripts among the 100 were concerning analgesia, weight loss, long-term potentiation, depolarization-induced suppression of inhibition, opiates and other topics. Cannabinoid type 1 (CB1) receptor was studied by more of the top 100 papers in comparison to cannabinoid type 2 (CB2) receptor. The most frequently mentioned chemicals in these publications were 2-arachidonoylglycerol, tetrahydrocannabinol, and anandamide. Together, these manuscripts comprise the most highly cited publications in the topic, literally the molecular neuroscience at its "high".

Keywords: Bibliometrics; Cannabis; Citation analysis; Endocannabinoid; Molecular neuroscience; VOSviewer.

Fig. 1

Publication timeline of the 100 most cited cannabis and cannabinoid-related manuscripts

Fig. 2

Bubble map showing words from titles and abstracts of the 100 most-cited cannabis manuscripts. Words from titles and abstracts were parsed, analyzed and visualized by VOSviewer. There were 113 terms that appeared in 5 or more manuscripts and hence were included in the map. Each bubble represents a word or phrase. The bubble size indicates its appearance frequency. The bubble color indicates the averaged citation count received by manuscripts containing the term. If two terms co-appeared in more manuscripts, the two bubbles are closer to each other. The lines indicate the 500 strongest co-appearance links between the terms

Fig. 3

Bubble map showing keywords listed by the 100 most-cited cannabis manuscripts. Keywords added by the authors and by Web of Science (KeyWords Plus) were analyzed and visualized by VOSviewer. There were 30 keywords that appeared in 5 or more manuscripts and hence included in the map. Each bubble represents a keyword. The bubble size indicates its appearance frequency. The bubble color indicates the averaged citation count received by manuscripts containing the keyword. If two keywords co-appeared in more manuscripts, the two bubbles are closer to each other. The lines indicate the 500 strongest links between the keywords

Fig. 4

The structures of the chemicals frequently mentioned in the top 100 cannabis-related manuscripts. The number of publications and citations per publication for each chemical are provided in brackets