It probably qualifies as a collective delusion that Arnold Schwarzenegger was a leading means of on-screen male wish-fulfilment in the 1980s. More than 30 years on, male wish-fulfilment still comes with those facilely superior Schwarzenegger features attached. His son, Patrick, plays the childhood imaginary friend who comes to the aid of a depressed student photographer in the new mental health-themed psychodrama Daniel Isn’t Real. At first, Daniel is egging on beleaguered Luke (Miles Robbins) to play the sensitive artist for the ladies; next thing, the alter ego is hijacking Luke’s body to engage in rough sex in underground tunnels and murdering his therapist.

Adam Egypt Mortimer’s film is good unclean fun, Luke’s psychological meltdown slathered all over in gooey effects. But, as you are probably gathering, it’s not the most sensitive depiction of mental illness ever made. It seems to pick up where Joker, another showboating work about a toxic proxy, left off. Medical professionals rounded on Todd Phillips’s film, accusing it of perpetuating “the hackneyed association between serious mental illness and extreme violence”. Into the same discourse, which is demanding greater care in terms of how mental health is represented on screen, swaggers Daniel Isn’t Real. It will face the same question: is this outré, batshit-crazy approach still acceptable?

Perhaps unsurprisingly, the upswell of public discussion around mental illness hasn’t resulted in a sudden increase in films about the subject. It’s a complex topic, rarely box-office gold. But the acknowledgement that mentally ill characters shouldn’t be consigned to the asylum of the criminally insane, like Psycho’s Norman Bates, dates back some time now. From One Flew Over the Cuckoo’s Nest (1975) to A Beautiful Mind (2001) to Silver Linings Playbook (2012), there has been more of a consensus that the mentally ill are protagonists, not villains, and deserve a sympathetic hearing. We are them, they are us.

But, despite this, the less restrained school of mental-health portrayal gallivants down the staircase. Joker’s perceived insensitivities haven’t stopped it raking in more than $1bn (£750m). Darren Aronofsky’s Black Swan (2010), with Natalie Portman plucking hallucinatory feathers from her goose pimples, doesn’t exactly take the documentary approach to the quest for artistic perfection.

Ditto Donnie Darko (2001) regarding teen alienation, with its interdimensional rabbit envoy, Frank. Steven Soderbergh’s wide lens-induced delirium in 2018’s Unsane was the digital-era equivalent of the Dutch angle, the off-kilter camera position habitually used to signify being in the presence of someone of unsound mind (Cesar Romero’s TV Joker often got the treatment).

With some of Joker’s defenders claiming it validated their experience as people with mental-health difficulties, as outsiders, it raises the question: what does an authentic approach to mental illness on screen entail? Maybe there are two broad approaches to the subject: an interior, realistic approach attuned to the detail of inner psychological shifts and an exterior one, such as in Joker, writing mental-health conditions large with lurid storylines and flamboyant visuals. But cinema – which lacks the novel’s privileged access to the mind – has a tendency to drift towards exteriorising: the easy visual, the dramatic flourish. Even films that are otherwise exemplary models of realism do this, such as Girl, Interrupted. Angelina Jolie’s Lisa is a kind of rock’n’roll wish-fulfilment figure for Winona Ryder’s narrator, not so different from Schwarzenegger Jr in Daniel Isn’t Real.

Facebook Twitter Pinterest Claire Foy in Unsane. Photograph: Allstar/New Regency

The exterior approach to mental health isn’t necessarily, as Joker’s critics might have it, the less authentic one. The visual vocabulary used by the likes of Shutter Island and Unsane – the deranged camera angles, high-contrast lighting – is derived from the German expressionism of 1920s, which had a hotline to the psychological forces bubbling beneath society. The jagged, distorted sets of The Cabinet of Dr Caligari either climb inside the head of the film’s hypnotist mastermind, or convey the dissociative state Conrad Veidt’s murderous sleepwalker falls into; the central gimmick of The Hands of Orlac – a concert pianist acquires a murderer’s hands in a transplant operation – is both totally ridiculous and a brilliant expression of suppressed rage.

In its intimate knowledge and fascination with extreme mental states, German expressionism was the inheritor of the gothic tradition. Joker follows this lineage explicitly: his iconic rictus is taken from The Man Who Laughs, a 1928 film by German expressionist Paul Leni, an adaptation of Victor Hugo’s gothic-tinged novel. The underlying idea – the horror of being unable to convey your inner feelings – is updated by Phillips in the light of today’s mental health epidemic.

We should bear this tradition in mind when we are presented with mental-health-related films on the more colourful end of the spectrum. Maybe realism isn’t important; these are the fantasies we are watching, the interior made exterior. The figure of the alter ego, that gothic favourite, is particularly important on this score. It’s amazing how often it crops up in some form in mental-health cinema, as a mouthpiece for the protagonist’s desires, sporting the badge of the id – from figments such as in Daniel Isn’t Real and Tyler Durden in Fight Club, to a person who becomes a vehicle for projected emotions such as in Girl, Interrupted and Black Swan, in which Portman obsesses over a rival ballerina.

Facebook Twitter Pinterest The Cabinet of Dr Caligari. Photograph: Allstar/Sinister Cinema/Sportsphoto Ltd

It’s as if these old expressionist mechanisms mirror the way a mind under pressure can flex and distort reality. This is one place fiction flows out of. So this approach is powerful when precisely deployed. It’s true that Joker is undisciplined about how it blurs the lines between Arthur Fleck’s inner life and the real world, giving licence to those who believe it both dangerously indulges the character and is irresponsible on the mental-health front. (The accusation is doubly true compared with its source film The King of Comedy, which draws clear moral lines around Rupert Pupkin’s delusional behaviour.) But Joker’s reckless approach is thankfully grounded in Joaquin Phoenix’s all-in performance, which suggests second-by-second lived understanding of mental instability.

Of course, the expressionist mental-health movie shouldn’t be the orthodoxy. There is a need for nuanced explorations of the topic – and those films do get made, though probably not frequently enough. But it would be a shame if the current call for respectful depictions ruled out an approach that can cleave the knot of the subject with splendid indelicacy. Depression and writer’s block doesn’t inevitably lead to an axe-murder spree, à la The Shining, but the film quickly captures a level of pent-up frustration most writers (and maybe some janitors) will understand.

The OTT approach doesn’t have to be taken literally, or some definitive statement that people with mental-health problems are dangerous. Fantasy is empowering too, in the right doses, in the right places. As Whoopi Goldberg’s nurse in Girl, Interrupted says: “Put it in your notebook ... get it out of yourself.” That is the positive takeaway from Joker and its ilk. Stifle that option, and Daniel Isn’t Real has words of warning instead: “The more you tell someone not to do something, the more they just go ahead and do it.”

Daniel Isn’t Real is out in cinemas, including book-your-own screenings via ourscreen.com, on 7 February; and Blu-Ray and digital HD on 10 February.

In the UK, Samaritans can be contacted on 116 123 or email jo@samaritans.org. You can contact the mental health charity Mind by calling 0300 123 3393 or visiting mind.org.uk