The Effect review: Is it love – or drugs? Lucy Prebble’s lab trial drama fires the synapses

‘I May Destroy You’ star Paapa Essiedu is vulnerable and charming in the first revival of ‘Succession’ writer Lucy Prebble’s 2012 play about whether we can tell the difference between antidepressants and placebos

Paapa Essiedu (Tristan) and Taylor Russell (Connie) in ‘The Effect’ (Marc Brenner)

“We’re going to look back on all this chemical imbalance stuff like it was the four humours,” says acid-tongued doctor Lorna in The Effect. It’s arguably a bit hypocritical of her to say the medical model of depression is a throwback, given that she’s in the middle of overseeing a clinical trial of antidepressants. But Lucy Prebble’s 2012 play – revived at the National Theatre in a flashy Jamie Lloyd production – perceptively shows that when it comes to mental health, we’re all still fumbling around in the dark, like medieval physicians who’ve dropped their tallow candles.

The play’s central question is a grabby one. Cocky Hackney drifter Tristan and sceptical Canadian psychology student Connie join the clinical trial for cash, but end up in love instead. Are their feelings real, or is it just artificial dopamine that’s giving them the heart eyes? And does it matter either way? Lloyd’s production makes them physically grapple with the question: piggybacks, wheelbarrows, and gymnastic horseplay in neat squares of white light, as they explore whether it’s their body or soul that means they can’t keep their hands off each other. Paapa Essiedu is all compelling, shambling, vulnerable charm. You can feel that he believes in the big stuff: god, love, fate. By contrast, Taylor Russell, recently seen alongside Timothée Chalamet in cannibal romance Bones and All, has an engaging, puncturing nerviness. Her fragility can’t quite hide her hunger for control over both her new boyfriend and the unknowable cosmos in general.

Prebble is so good at stripping away the squishy stuff and showing the bare bones of relationships: the power struggles, the raw need