Tricyclic antidepressants may delay need for Parkinson’s therapy
MedWire News: Patients with early Parkinson's disease (PD) take longer to initiate dopaminergic therapy if they are taking tricyclic antidepressants such as amitriptyline, as opposed to other classes of antidepressant or none, report researchers.
The finding indicates that tricyclic antidepressants could be the most effective at altering the judgment of need for dopaminergic treatment, says the team.
"These results also illustrate the importance of treating both the motor and non-motor symptoms associated with PD, as both types of symptoms contribute greatly to disability," suggest Timothy Collier from Michigan State University, Grand Rapids, USA, and co-investigators.
Collier and team analyzed time to initiation of symptomatic therapy in 2064 early PD patients from six clinical trials, according to depression and antidepressant use in the population.
A total of 451 patients were taking an antidepressant (either a tricyclic, a selective serotonin uptake inhibitor, a serotonin-norepinephrine re-uptake inhibitor, or an atypical antidepressant), and depression severity was defined as none, mild, or moderate/severe based on the cutoffs of depression scales used in the trials.
In analysis stratified by type of antidepressant taken, the percentage of patients not using symptomatic therapy for their PD after 1 year (the average halfway point of the six trials) was significantly higher among those taking amitriptyline, than those not taking antidepressants, report Collier et al.
Furthermore, they found that after controlling for factors including depression, age, and treatment group, patients taking amitriptyline and other tricyclics were 70% less likely to have initiated symptomatic therapy than patients who took other antidepressants.
After controlling for antidepressant use, mild depression increased the probability of starting dopaminergic therapy 1.4-fold. Presence of moderate/severe depression did not have this effect, however.
Finally, patients' Unified Parkinson's Disease Rating Scale (UPDRS) outcomes were not significantly different according to antidepressant use. This suggests that even for patients on antidepressants who did not require symptomatic PD therapy after 1 year, motor function did not necessarily worsen less than their counterparts not taking antidepressants, write the investigators in Movement Disorders.
"Despite finding no change in UPDRS scores, the association of treated or untreated mild depression with a higher probability of beginning dopaminergic therapy suggests a role for depression in increasing overall disability and possibly accelerating disease progression," conclude the researchers.
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By Sarah Guy