Parkinson's, anti-depression drugs' surprise mood effects

Pills in hand

A recent trial of common drugs used to treat Parkinson’s and depression has shown that not only do they treat the medical problem, they have an unintended side effect of altering patients’ moods.

Obviously dealing with these medical problems is bad enough, let alone any change in mood affecting you or your loved ones.

Using pairs of people, study participants were given mildly painful electric shocks. The person giving the shock were told that receivers would be at the receiver’s own pain threshold. Money was given to the participants, for the purpose of essentially buying or selling the shocks given or received. Some were given a placebo, others a dose of citalopram, a seratonin-based drug, and the third group were given levodopa, the drug used to treat Parkinson’s disease.

The University of Oxford psychologist that led the study, Molly Crockett, noted that more work is needed to understand the full effect of these drugs.

“Patients [taking these drugs] are tracked in terms of how their symptoms improve, but not necessarily in terms of how their behaviour changes,” she said. “In the treatment of Parkinson’s, some patients go on to develop compulsive gambling and compulsive sexual behaviour. The drugs have consequences that reach out into the world beyond the patient”.

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She added that it was unclear whether the effects seen in the study would be replicated in patients. An alternative possibility is that the drugs could bring the behaviour of patients “back to baseline” by stabilising their psychological state.

The central message is we need to have more research into how these drugs affect behaviour, both in healthy people and in people taking them for disorders.

The results of this ’shocking’ experiment were these. Those that took citalopram were more inclined to do less ‘harm’ via the shocks. Those on the levodopa dose were less inclined to lessen their experiment partner’s pain, indicating a higher degree of selfishness.

It sounds an odd experiment, but the psychologists in the study see it as an area worthy of more work.

Have you ever noticed a change in mood based on taking these – or indeed any other – medications? Particularly when you were not told about them by your doctor?