OBJECTIVE: To investigate the effectiveness of stimulants in patients with depression, by using naturalistic outcome measures, such as psychiatric admissions, psychiatric bed-days and incidents of intentional self-harm or suicide attempts.
METHODS: Via linkage of the Danish nationwide health registers, we identified all patients with a diagnosis of depression initiating stimulants, including methylphenidate, modafinil, amphetamine, dexamphetamine or lisdexamphetamine, from 1995 to 2012. We used a mirror-image model to test whether redemption of a stimulant prescription was associated with a reduction in psychiatric admissions, inpatient days and incidents of intentional self-harm or suicide attempts. Specifically, the number of these outcomes in the 2 years leading up to redemption of a stimulant prescription was compared to the two subsequent years. Similar outcomes were used in a reverse mirror-image model to investigate the effect of stimulant termination.
RESULTS: A total of 3354, 935 and 105 patients diagnosed with depression redeemed prescriptions for methylphenidate, modafinil or amphetamine/dexamphetamine/lisdexamphetamine, respectively. Initiation of methylphenidate was not associated with a significant change in psychiatric admissions (mean: -0.02 admissions, p = 0.11) or inpatient days (mean: 0.13 days, p = 0.74). Similar findings were made for modafinil and the amphetamines. In addition, no clinically relevant change in psychiatric admissions or inpatient days was found after termination of a stimulant. After initiation of methylphenidate, the incidents of self-harm or suicide attempts were reduced by 54%, from 68 to 31 events (p = 0.004). No significant change in incidents of self-harm or suicide attempts were found for modafinil or the amphetamines.
CONCLUSION: This nationwide study, using naturalistic outcomes, does not support the use of stimulants in patients with depression. However, the use of methylphenidate was associated with a 54% reduction in incidents of self-harm or suicide attempts, indicating that methylphenidate may potentially be useful in patients with depression with suicidal- or self-harming behaviour. However, further studies are needed, before any firm conclusions can be made.