1 Department of Neuroscience, ABC Health University Center, Santo André, SP, Brazil Department of Psychiatry, Medical School, University of São Paulo, São Paulo, SP, Brazil

2 Department of Psychiatry, University of Michigan, Ann Arbor, MI, U.S

3 Serbian Academy of Sciences and Arts, Belgrade, Serbia

4 Department of Psychiatry, National Institute of Mental Health and Neurosciences, Bangalore, India

5 Anxiety Disorders Center, Buenos Aires, Argentina

6 Centre for Psychiatry, Imperial College, London, UK

7 Department of Psychiatry, University of Bonn, Bonn, Germany

8 Department of Psychiatry, School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa


There is evidence of a progressive increase in the number of Randomized Controlled Trials (RCTs) in the area of psychiatry. However, some areas of psychiatry receive more attention from researchers potentially to the detriment of others.

Aiming to investigate main gaps for RCTs in psychiatry, the present bibliometric study analysed the bi-annual and five-year rates of RCTs in the main database of medical studies (Pubmed) over the 1999–2018 period (n = 3,449). This analysis was carried out using the ICD-10 mental and behavioural chapter. ICD-10, was the edition of the manual used throughout the above period.

Overall, after 16 years of considerable increase in the bi-annual absolute number of RCTs, there has been a slowdown in the last 4 years, similar to other medical areas. Affective, organic and psychotic disorders, and depression, schizophrenia and dementia were the top studied groups and disorders respectively – ahead of other groups/diagnoses. For substance use disorders, there has been a decrease of RCT in the last 5 years, in line with the fall of alcohol use disorder in the ranking of most studied disorders. Delirium and mild cognitive disorder are both ascending in this ranking. Personality disorders and mental retardation stand out as the least studied groups over the whole assessment period.

Novel treatments, ease of access to patient populations, and ‘clinical vogue’, seem to be more important in guiding the undertaking of RCTs than the actual need as indicated by prevalence and/or burden of disorders and public health impact. Regarding specific disorders, acute/transient psychosis; mixed anxiety and depression; adjustment disorder; dissociative and conversion disorders; somatization; hypochondria; and neurasthenia, would deserve future RCTs. Clinical researchers and editors of scientific journals should give special attention to the less studied areas and disorders, when considering conducting and publishing RCT studies, respectively.