At what age do biomedical scientists do their best work?

Several human characteristics that influence scientific research performance, including set goals, mental and physical abilities, education, and experience, may vary considerably during the life cycle of scientists. We sought to answer the question of whether high-quality research productivity is associated with investigator's age. We randomly selected 300 highly cited scientists (50 from each of 6 different biomedical fields, specifically immunology, microbiology, neuroscience, psychology-psychiatry, clinical medicine, and biology-biochemistry). Then, we identified the top 5 highly cited articles (within 10 yr after publication adjusted for the expansion of the literature) as first author of each of them. Subsequently, we plotted the distribution of the 1500 analyzed articles of the 300 studied scientists in the eight 5-year intervals of investigator's age during the year of article publication (21-25 to 55-60 yr of age), adjusted for person-years of contribution of each scientist in the various age groups. Highly cited research productivity plotted a curve that peaked at the age group of 31-35 yr of age and then gradually decreased with advancing age. However, a considerable proportion of this highly cited research was produced by older scientists (in almost 20% of the analyzed articles, researchers were older than 50 yr). The results were similar in another analysis of the single most cited article of each studied scientist. In conclusion, high-quality scientific productivity in the biomedical fields as a function of investigator's age plots an inverted U-shaped curve, in which significant decreases take place from around 40 yr of age and beyond.