Emmons RA, McCullough ME Counting blessings versus burdens: an experimental investigation of gratitude and subjective well-being in daily life. J Pers Soc Psychol. 2003 Feb;84(2):377-89.
Froh JJ, Sefick WJ, Emmons RA Counting blessings in early adolescents: an experimental study of gratitude and subjective well-being. J Sch Psychol. 2008 Apr;46(2):213-33. doi: 10.1016/j.jsp.2007.03.005. Epub 2007 May 4.
Jackowska M, Brown J, Ronaldson A, Steptoe A The impact of a brief gratitude intervention on subjective well-being, biology and sleep. J Health Psychol. 2016 Oct;21(10):2207-17. doi: 10.1177/1359105315572455. Epub 2015 Mar 2.
Kruse, E , Chancellor, J., Ruberton, P.M., & Lyubomirsky, S. (2014). An upward spiral between gratitude and humility. Social Psychological and Personality Science. 5(7), 805-814. doi: 10.1177/1948550614534700
Rash, J A., Matsuba, M. K., & Prkachin, K. M. (2011). Gratitude and well-being: who benefits the most from a gratitude intervention? Applied Psychology: Health and Well-Being, 3(3), 350-369. doi: 10.1111/j.1758-0854.2011.01058.x
Sheldon, K M. & Lyubomirsky, S. 2006. How to increase and sustain positive emotion: The effects of expressing gratitude and visualizing best possible selves. The Journal of Positive Psychology. 1(2). 73-82. doi:10.1080/17439760500510676
Watkins, P , Woodward, K., Stone, T., & Kolts, R. (2003). Gratitude and happiness: Development of a measure of gratitude and relationships with subjective well-being. Social Behavior and Personality: An international journal, 31, 431-452. doi: 10.2224/sbp.2003.31.5.431
Zion SR, Crum AJ Mindsets Matter: A New Framework for Harnessing the Placebo Effect in Modern Medicine. Int Rev Neurobiol. 2018;138:137-160. doi: 10.1016/bs.irn.2018.02.002. Epub 2018 Mar 20. Review.
Cultivating Gratitude: Does Manipulating Expectations Improve the Efficacy of a Gratitude Intervention?
Interventional studies are often prospective and are specifically tailored to evaluate direct impacts of treatment or preventive measures on disease.
Observational studies are often retrospective and are used to assess potential causation in exposure-outcome relationships and therefore influence preventive methods.
Expanded access is a means by which manufacturers make investigational new drugs available, under certain circumstances, to treat a patient(s) with a serious disease or condition who cannot participate in a controlled clinical trial.
Clinical trials are conducted in a series of steps, called phases - each phase is designed to answer a separate research question.
Phase 1: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
Phase 2: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.
Phase 3: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
Phase 4: Studies are done after the drug or treatment has been marketed to gather information on the drug's effect in various populations and any side effects associated with long-term use.