Trends in mental health clinical research: Characterizing the ClinicalTrials.gov registry from 2007-2018

While the epidemiologic burden of mental health disorders in the United States has been well described over the past decade, we know relatively little about trends in how these disorders are being studied through clinical research. We examined all US interventional mental health trials submitted to ClinicalTrials.gov between October 1, 2007 and April 30, 2018 to identify trends in trial characteristics, comparisons with non-mental health trials, and trial attributes associated with discontinuation and results reporting. International data were excluded to minimize potential confounding. Over this period, mental health and non-mental health trials grew at similar rates, though Industry and US government-funded trials declined and academic medical center/hospital/other (AMC/Hosp/Oth) funded trials grew faster in mental health research. The proportion of trials with safeguards against bias, including blinding and oversight by data monitoring committees (DMCs), decreased. This occurred during growth in the proportion of trials studying behavioral and non-pharmacological interventions, which often cannot be blinded and do not require DMC oversight. There was concurrent decline in pharmaceutical trials. There was significant growth in trials studying Non-DSM (Diagnostic and Statistical Manual-5) conditions (e.g. suicidality and wellness), as well as substance use, anxiety, and neurocognitive disorders. One in 12 trials was discontinued. Trial discontinuation was associated with industry and AMC/Hosp/Oth funders, pharmaceutical interventions, and lack of DMC oversight. Only 29.9% of completed trials reported results to the registry. Decreased results reporting was associated with behavioral interventions, phase 1 trials, and industry and AMC/Hosp/Oth funders. The main implications of these data are that funding is shifting away from traditional government and industry sources, there is increasing interest in non-pharmacological treatments and Non-DSM conditions, and there are changing norms in trial design characteristics regarding safeguards against bias. These trends can guide researchers and funding bodies when considering the trajectory of future mental health research.