Contemplating getting old and thinking about what it would be like living out your last years institutionalised in a care home is enough to make anyone feel depressed. Sure, there are some excellent care homes out there, but there are also plenty that are steeped in loneliness and misery. And the prospect of losing your physical – or, even worse, your mental – faculties is deeply scary.

That gut reaction – an inherent fear of decline – is a very strong one, difficult to overcome. It infuses our attitudes towards ageing and helps bake ageism into society. Ageing is culturally all about managing decline rather than living the good life until the very end. That, in turn, affects how older people are looked after by their families and the care system.

In the 1950s, the psychoanalyst Isabel Menzies Lyth observed how hospitals organised caring for older people as a series of physical tasks, each of which was carried out by a different nurse, to protect them from the emotional stress of confronting dying and loss. Things aren’t as bad as that these days, but that approach to caring as routine physical labour still overly defines our approach to professional care.

More often than not, care homes are dreadfully risk-averse places: ironically, given you’re approaching the end of your days, you often lose the right to drink yourself silly, smoke yourself to death or keep a pet. These well-intentioned attempts to eradicate any risk of physical harm lead to the miserable infantilisation of older people. The thought of it is enough to make me shudder.

There’s also an assumption that anything over and above what an increasingly stretched care system can provide must be provided from within families. In other words, ageing parents should simply rely on their children to look after them in an intergenerational turning of the tables. But what if you don’t have children, or they don’t want to or can’t afford to look after you, or you don’t want to have to rely on them?

The way we do ageing in this country is certainly not what I want or envisage for myself or my loved ones. But if we’re going to change it, I think we have to find a way of short-circuiting that base human instinct that sees ageing as primarily about decline. Bill Thomas, a doctor based in the US, who was known for filling a care home with a menagerie of cats, dogs, rabbits and parakeets in the 1990s, argues that we need to reimagine our last few years as a time we can continue to live rich, meaningful lives filled with love, even as our minds and bodies are declining.

Great relationships are obviously critical to anyone’s wellbeing, regardless of how old they are. But the key to a good end of life could also lie in embracing hedonism. Once we ensure that everyone can achieve a basic standard of living and care in their older age, if necessary through state support, it becomes easier to see that there’s perhaps no better time to be hedonistic than in your 80s and 90s, when you’ve discharged your professional and family responsibilities and your body isn’t quite the temple it once was.

Let’s call this the age of irresponsibility. And, in that spirit, what better place to start than with a radical liberalisation of drugs policy? Forget drinking or smoking: why shouldn’t older people in a care home be able to dabble in drugs that in controlled forms are actually less harmful and addictive than booze or tobacco? Why shouldn’t I be able to take MDMA while listening to house music if that’s what I want to do when I’m 85? Or have fun tripping on magic mushrooms? Or eat some hash brownies?

Facebook Twitter Pinterest Timothy Leary, the LSD activist turned computerised hallucination designer, died of cancer in 1996 at the age of 75. Photograph: AP

When it comes to legalised substances we regard as dangerous, the classic approach is to legislate a minimum age of responsibility, usually 18, when we believe people are adult enough to assess the benefits and risks of partaking for themselves. But our age of irresponsibility could kick in at, say, 75 or 80, after which people become freer to take risks precisely because they are approaching the end of their days.

Hedonism aside, there are other arguments for doing this. Medical research about the benefits of banned drugs is difficult to undertake precisely because of their illicit status. But David Nutt, a scientist who is researching the impact of psychedelic drugs on depression and anxiety, highlights trials that suggest that taking psilocybin (the active ingredient in magic mushrooms) might potentially help people come to terms with dying.

The case for drugs liberalisation and regulation is most often couched in pragmatism rather than hedonism: the strong evidence that decriminalising and regulating drugs reduces harm by making drug-taking safer, saving cash on policing that can be spent instead on treating and preventing addiction and reducing the organised crime fuelled by the black-market drug trade. That’s completely understandable: you’re more likely to win round the hearts and minds that hold the reins of power to drug liberalisation through utilitarian arguments rather than waxing lyrical about the joys of raving on MDMA.

But while an appeal to hedonism may be unlikely to clinch the deal in terms of a universal liberalisation of drugs policy, I reckon it could prove hugely useful in helping us rethink our approach to ageing. Longer life expectancies are certainly a cause for celebration, but when you think about the realities of suffering from dementia or a broken hip, it can be hard to muster up unequivocal enthusiasm, even as you’re aware how lucky you would be to make it to 90. Embracing an age of irresponsibility could help change that. And, who knows, it could tip us down a benign slippery slope that ends with a liberalised approach to drugs for everyone.

• Sonia Sodha is an Observer columnist