We all know a lack of exercise is bad for our bodies. So what is relying on AI doing to our brains? | Devi Sridhar

When I was a postgraduate student at the University of Oxford in the early 2000s, I interviewed for a major consulting firm. All my friends were being recruited, and I thought why not give it a shot? Aside from the usual maths-proficiency test (how quickly can you crunch numbers in front of a client and look smart), I was asked about what the future of streaming could look like. I gave a long-winded answer about the unintended consequences of changing how humans interact with each other when a new technology is introduced, and why this may not be in the best interests of health and society.I even remember saying something like: “Can you imagine just being stuck at home, alone, watching show after show and never having to move or see any other people? Why would anyone choose that over going out to rent a DVD at a local shop, or to a movie theatre?” You won’t be surprised to learn that I wasn’t invited for a follow-up interview.The partner at the consulting firm thought my answer was completely wrong. They saw the potential growth and profitability of streaming – and you could say, in hindsight, they had a point: Netflix’s global revenue continues to rise year on year, reaching $12.6bn (£9.5bn) in 2026. My answer, on the other hand, focused on its societal and health consequences.But if you look at the negative impact that excessive screen-time has had on health and wellbeing, especially on children, perhaps I wasn’t wrong after all. We know that social isolation is now widespread, anxiety and depression too, with sleep also negatively affected by how late we stay up watching content.And here I am, more than 20 years later, being asked to talk about AI and what it means for higher education, health and society at a conference at the University of Edinburgh, where I work as a professor. I know many people would say: “It’s wonderful! Our lives will all get easier.” But we’re also moving closer to a world where we don’t have to see anyone, move anywhere or use our brains, seemingly at all. And again I think, wonderful for who? Wonderful for the tech companies and those looking to cut costs by replacing humans with automation, but certainly not for the rest of us.There’s a comparison, for me, between the effects of streaming on our physical activity levels and health, and the probable effects of AI on our brains. The richer a country becomes, the more people move into non-manual labour, with sedentary activities in their free time. We can see evidence for this if we look at development in low- and middle-income countries: physical activity goes down as GDP per capita goes up. Over the past few decades, we have seen the health consequences of sedentary behaviour grow: higher rates of chronic disease such as cancers and type-2 diabetes, more chronic back and neck pain, and reduced quality of life. Physical movement has become a leisure activity to stay healthy, and is increasingly linked with higher socioeconomic status in places such as the UK.We know that not using our bodies is bad for our physical health – but what is regular reliance on AI doing to our minds? The true causal evidence might take decades to emerge, but we can link several trends together to guess at an answer. We know, for example, that AI use and daily screen-time averages are going up. At my university, I’d guess almost all students are using some kind of generative AI (gen AI) to produce their work, raising huge challenges when it comes to assessment.The 2026 Higher Education Policy Institute survey of students’ use of gen AI found this year that 95% of undergraduates reported using AI in at least one way, and 94% said they had used it in assessed work. We also know that overall educational attainment levels are decreasing: a recent OECD report noted that student performance across its member countries continued to decline, with the lowest average ever recorded for maths and reading. The report links these poor scores to longer screen-time, increased digitalisation in the classroom and the collapse in reading for enjoyment among children.skip past newsletter promotionafter newsletter promotionAll of this makes me wonder what will happen to our brains as we continue to outsource key cognitive functions to AI. We already have preliminary evidence from a study that used electroencephalography (EEG) sensors to measure electrical activity in the brain, titled Your Brain on ChatGPT: it showed those students using gen AI to write essays had weaker and less distributed brain connectivity than those writing fully on their own.We also know that a lack of mental engagement can lead to losing cognitive function over time. A study of more than 19,000 adults over the age of 50 found greater participation in cognitively stimulating leisure activities (such as crosswords or sudoku) was linked to lower dementia risk and better cognitive functioning in later life. Just as resistance training is important to maintain muscle mass as we age, our brains also need regular training. Use it or lose it.As we look to the future, will thinking, reading, writing and actively using our brains become activities from a bygone era? If we stop using our brains to think, socially interact, concentrate or problem-solve, what will be the impact on our quality of life and our chances of ageing healthily? Will we see a rise in chronic disease linked to the brain?And, maybe just as importantly, does anyone even care? It’s certainly not the concern of tech companies, which are in an arms race to go faster. And so we’re heading in that direction and being told it’s all wonderful. Yes, it is wonderful for certain tech companies. And probably terrible for the mental health and wellbeing of the rest of us. Prof Devi Sridhar is chair of global public health at the University of Edinburgh