The use of stimulants in depression: Results from a self-controlled register study

A target trial emulation comparing the antidepressant effectiveness of selective serotonin reuptake inhibitors (SSRIs) highlighting the importance of patent-related confounding by indication

BACKGROUND

The comparative effectiveness of selective serotonin reuptake inhibitors (SSRIs) has been subjected to relatively little research. However, a recent study based on target trial emulation suggested that sertraline may be more effective than escitalopram.

AIMS

To investigate whether sertraline, citalopram, and escitalopram differ in their effectiveness-assessed via the risk of psychiatric hospital admission and suicide following treatment initiation. The choice to focus on sertraline, citalopram, and escitalopram was made to limit confounding by indication, as the Danish depression treatment guideline from 2007 specifically listed these three SSRIs as first choice.

METHOD

We conducted a target trial emulation based on data from Danish registers. We identified all individuals that initiated treatment for depression with sertraline, citalopram, or escitalopram in the period from January 1, 2007, to March 1, 2019. These individuals were followed until psychiatric hospital admission or suicide (separate analyses), death, 1 year after treatment initiation or end of data. Cox proportional hazards regression adjusted for relevant baseline covariates was performed to emulate randomized treatment allocation, comparing the rate of psychiatric hospital admission and suicide for individuals treated with sertraline (used as reference), citalopram or escitalopram, respectively. For escitalopram, we conducted a sensitivity analysis excluding data from the period during which the drug was sold under patent, as the price of the drug during that time likely entailed a different prescription pattern, increasing the risk of ("patent-related") confounding by indication.

RESULTS

We identified 56,865, 118,145, and 31,083 individuals initiating treatment with sertraline, citalopram, and escitalopram, respectively. Using sertraline as reference, the adjusted hazard rate ratio (aHRR) for psychiatric admission was 0.98 (95% CI = 0.91-1.05) for citalopram and 1.21 (95% CI = 1.10-1.32) for escitalopram. Notably, in the sensitivity analysis only including patients initiating treatment after the escitalopram patent had expired, the increased risk of psychiatric hospital admission associated with escitalopram treatment was no longer present (aHRR = 0.98, 95% CI = 0.82-1.18). The results of the analyses of suicide were inconclusive, due to few outcome events.

CONCLUSIONS

Sertraline, citalopram, and escitalopram do not seem to have differential effectiveness in the treatment of depression. Taking potential patent-related, time varying, confounding by indication (via severity) into account is critical for pharmacoepidemiological studies, including those employing target trial emulation.

Revisiting the association between treatment with antidepressants and mania: A nationwide within-individual study of 3554 patients with bipolar disorder

INTRODUCTION

Antidepressants are commonly used "off-label" for bipolar depression, despite concerns over the risk of potential treatment-emergent mania (or "manic switch"). Treatment-emergent mania is difficult to study with adequate power in clinical trials as it requires a large group of participants and long follow-up. Therefore, naturalistic register-based studies have been applied to assess this phenomenon. Here, we aimed to replicate previous findings and address key methodological limitations that were not previously taken into account.

METHODS

We utilized data from nationwide Danish health registries to identify patients with bipolar disorder treated with an antidepressant, either with or without concomitant treatment with a mood stabilizer (drug treatment proxied via redeemed prescriptions). We plotted the incidence of manic and depressive episodes relative to the initiation of antidepressant treatment and compared the incidence of mania in the period prior to and following initiation of antidepressant treatment (within-individual design).

RESULTS

In 3554 patients with bipolar disorder initiating treatment with an antidepressant, the number of manic episodes peaked approximately 3 months prior to initiation of antidepressant treatment, and the number of depressive episodes peaked around the initiation of antidepressant prescription. This temporal pattern suggests that antidepressants were used to treat post-manic depression.

CONCLUSION

Within-individual designs do not control sufficiently for confounding by indication, when the treatment indication is time-varying. Thus, results from prior within-individual studies of antidepressant treatment in the context of bipolar disorder may be invalid due to time-varying confounding by indication.

Impulsivity in Depression: Its Relation to Suicidality

OBJECTIVE

Impulsivity is an important risk for suicidality, which is common in patients with major depressive disorder (MDD). The goal of this study was to examine multiple facets of impulsivity in depressed patients compared with healthy controls and to assess their relationship to suicidality.

METHOD

Outpatients diagnosed with MDD using the Structured Clinical Interview for DSM-IV were recruited. Two groups were constituted as "MDD in remission" (n=32) and "MDD" (n=71). The "healthy control" group (n=30) consisted of individuals who had never been diagnosed with any psychiatric disorder. Impulsivity was assessed with the Barratt Impulsivity Scale (BIS), a self-rating measure, and with the following behavioral tasks: Go/No-go Task, Iowa Gambling Task, and Balloon Analogue Risk Task. The scores of the 3 groups (n=133) were compared to evaluate the effect of MDD. The scores were also analyzed and compared in the patients in the 2 MDD groups (n=103) with respect to their current and lifetime suicidality.

RESULTS

There was no difference in the 3 groups in task scores, but nonplanning BIS was correlated with the severity of depressive symptoms. Patients with suicidal ideation (SI) had higher BIS total and attention impulsivity scores and more commission errors on the Go/No-go Task, reflecting failure in response inhibition, compared with the patients without SI.

CONCLUSIONS

Failure to show differences in impulsivity-related tasks suggests that there might be no relationship between the state of depression and impulsivity. However, these findings confirm that there is an association between SI and response inhibition and the attention facet of impulsivity in depression.

Risk of Mania After Methylphenidate in Patients With Bipolar Disorder

BACKGROUND

Bipolar disorder and attention-deficit/hyperactivity disorder are common comorbidities. Attention-deficit/hyperactivity disorder is commonly treated with stimulants (eg, methylphenidate), which, however, have been suggested to cause treatment-emergent mania in patients with bipolar disorder. Here, we assessed the risk of mania, depressive episodes, and psychiatric admissions after initiation of methylphenidate treatment in patients with bipolar disorder.

METHODS

Using Danish health registries, we identified all individuals registered with a diagnosis of bipolar disorder from January 1, 2000, to January 1, 2018, who were treated with methylphenidate. We applied a 1-year mirror-image model to compare the occurrence of mania, depression, and psychiatric admissions in the period leading up to and after methylphenidate treatment initiation. We furthermore assessed the trend in these outcomes from 4 years before to 1 year after initiation of methylphenidate treatment.

RESULTS

A total of 1043 patients with bipolar disorder initiated treatment with methylphenidate. The number of manic episodes decreased by 48% after methylphenidate treatment initiation (P = 0.01), both among patients using mood stabilizers (-50%) and among patients not using mood stabilizers (-45%). The number of manic episodes, however, peaked approximately 6 months before methylphenidate. The results were similar for the secondary outcomes.

CONCLUSIONS

Initiation of methylphenidate treatment was not associated with an increased risk of mania in patients with bipolar disorder. A decrease in mania, depressive episodes, and psychiatric admissions was observed after methylphenidate. However, these decreases seemed to be driven by regression to the mean after clinical deterioration preceding methylphenidate treatment, rather than by the methylphenidate treatment itself.

The Convergence Model of Brain Reward Circuitry: Implications for Relief of Treatment-Resistant Depression by Deep-Brain Stimulation of the Medial Forebrain Bundle

Deep-brain stimulation of the medial forebrain bundle (MFB) can provide effective, enduring relief of treatment-resistant depression. Panksepp provided an explanatory framework: the MFB constitutes the core of the neural circuitry subserving the anticipation and pursuit of rewards: the “SEEKING” system. On that view, the SEEKING system is hypoactive in depressed individuals; background electrical stimulation of the MFB alleviates symptoms by normalizing activity. Panksepp attributed intracranial self-stimulation to excitation of the SEEKING system in which the ascending projections of midbrain dopamine neurons are an essential component. In parallel with Panksepp’s qualitative work, intracranial self-stimulation has long been studied quantitatively by psychophysical means. That work argues that the predominant directly stimulated substrate for MFB self-stimulation are myelinated, non-dopaminergic fibers, more readily excited by brief electrical current pulses than the thin, unmyelinated axons of the midbrain dopamine neurons. The series-circuit hypothesis reconciles this view with the evidence implicating dopamine in MFB self-stimulation as follows: direct activation of myelinated MFB fibers is rewarding due to their trans-synaptic activation of midbrain dopamine neurons. A recent study in which rats worked for optogenetic stimulation of midbrain dopamine neurons challenges the series-circuit hypothesis and provides a new model of intracranial self-stimulation in which the myelinated non-dopaminergic neurons and the midbrain dopamine projections access the behavioral final common path for reward seeking via separate, converging routes. We explore the potential implications of this convergence model for the interpretation of the antidepressant effect of MFB stimulation. We also discuss the consistent finding that psychomotor stimulants, which boost dopaminergic neurotransmission, fail to provide a monotherapy for depression. We propose that non-dopaminergic MFB components may contribute to the therapeutic effect in parallel to, in synergy with, or even instead of, a dopaminergic component.

Self-Harm and Suicide Attempts Preceding and Following Electroconvulsive Therapy: A Population-Based Study

OBJECTIVE

The beneficial effect of electroconvulsive therapy (ECT) on suicidality has been documented in clinical trials, whereas naturalistic studies on the topic are scarce and restricted to individuals with mood disorders. Here, based on population-based data from Danish registers, we aimed to investigate the course of self-harm and suicide attempts preceding and following ECT across 4 major mental disorders. This was done to examine whether data from the real-world clinical setting are compatible with the positive results from clinical trials.

METHODS

We identified all patients diagnosed with unipolar depression (n = 8843), bipolar disorder (n = 2713), psychotic disorder (n = 2692), or personality disorder (n = 2085) who received ECT for the first time in the period from 2008 to 2019, as well as age-, sex-, diagnosis-, illness duration-, and admission-matched comparison groups not receiving ECT. A mirror-image model was used to examine whether the number of incidents of self-harm/suicide attempts changed following ECT (paired t test).

RESULTS

There were substantial and statistically significant reductions in the number of incidents of self-harm/suicide attempts when comparing the month leading up to and the month following initiation of ECT for all diagnostic groups (unipolar depression: reduction, 83% [P < 0.001]; bipolar disorder: reduction, 72% [P < 0.001]; psychotic disorder: reduction, 82% [P < 0.001]; personality disorder: reduction, 83% [P < 0.001]). The analog results for the comparison groups not receiving ECT suggested that these reductions in self-harm/suicide attempts were partly mediated by a protective effect of admission.

CONCLUSIONS

Data from the real-world clinical setting are compatible with results from clinical trials with regard to the protective effect of ECT on suicidality.

Stimulant use for self-management of pain among safety-net patients with chronic non-cancer pain

BACKGROUND

Chronic pain affects one-fifth of US adults. Reductions in opioid prescribing have been associated with increased non-prescription opioid use and, chronologically, increased stimulant (methamphetamine and cocaine) use. While non-prescription opioid use is commonly attributed to pain self-management, the role of stimulants in managing pain is unclear.

METHODS

We analyzed baseline data from a longitudinal study of patients with chronic non-cancer pain in an urban safety-net healthcare system who had been prescribed an opioid for ≥3 of the last 12 months, and had a history of non-prescription opioid, cocaine, or amphetamine use (N = 300). We estimated the prevalence and identified correlates of stimulant use to treat pain among a subgroup of patients who reported past-year stimulant use (N = 105). Data sources included computer-assisted questionnaire (demographics, substance use, pain), clinical exam and procedures (pain, pain tolerance), and chart abstraction (opioid prescriptions). We conducted bivariate analyses to assess associations between demographics, pain characteristics, non-opioid therapies, substance use, opioid prescriptions, and self-reported symptoms, with reporting using stimulants to treat pain. Demographic variables and those with significant bivariate associations were included in a multivariable logistic regression model.

RESULTS

Fifty-two percent of participants with past-year stimulant use reported using stimulants in the past year to treat pain. Participants who used stimulants for pain reported slightly higher average pain in the past 3 months (median of 8 (IQR: 6-8) vs 7 (7-9) out of 10, p = 0.049). In the multivariable analysis, female gender (AOR= 3.20, 95% CI: 1.06-9.63, p = 0.039) and higher score on the Douleur Neuropathique 4 neuropathic pain questionnaire (AOR = 1.34, 95% CI: 1.05-1.70, p = 0.017) were associated with past-year stimulant use to treat pain.

CONCLUSION

Stimulants may be used for pain self-management, particularly for neuropathic pain and among women. Our findings suggest an underexplored motivation for stimulant use in an era of reduced access to prescribed opioids.