For the research, the study authors pulled information from a large prescription claims database. The study included more than 162,000 patients aged 10 to 64 with a diagnosis of depression who started taking an SSRI medication between 1998 and 2010.
Researchers restricted their analysis to three of the most commonly prescribed antidepressants, Celexa, Zoloft and Prozac. And they separated users into those who started at the recommended dosages of those medications, or those who were prescribed higher-than-recommended doses of the drugs.
The normal doses were 20 milligrams per day for Celexa, 50 milligrams per day for Zoloft and 20 milligrams per day for Prozac. Patients who were initially prescribed more than one drug were excluded from the study.
Nearly 18 percent of patients in the study were started on doses that were higher than those, in conflict with current medical guidelines.
Then researchers checked patients’ medical records to see how many had committed acts of deliberate self-harm within a year of starting their medications.
Among those younger than 24, patients on higher doses harmed themselves at roughly twice the rate of those on lower doses. During the study period, there were 32 incidents of self-harm for every 1,000 young patients taking high doses while there were only 15 such incidents per 1,000 patients taking recommended doses.