An additional 2.5 million people in England will be living with major illnesses such as cancer, diabetes, dementia and depression by 2040, according to a new report.

The study from the Health Foundation found that 9.1 million people in England will have a major illness – an increase of 37% compared with 2019.

“Almost one in five of the population are projected to be living with major illness by then, an increase of more than a third,” the report said.

“By comparison, the working age population is projected to increase by only 4% – this population group will be responsible for generating the bulk of Government revenues used to fund public services including the NHS.”

Cases of dementia are expected to rise 45% by 2040, heart failure by 92%, cancer by 31%, diabetes by 49%, chronic pain by 32% and anxiety or depression by 16%.

At the age of 70, people will have an average of three long-term conditions, rising to more than five by the age of 85, researchers said.

They said four-fifths of the jump in major illnesses will be driven by an ageing population, with people living longer meaning they are more likely to encounter – and live with – ill health.

Around 80% (two million people) of the projected increase in major illness will affect those aged 70 and over.

The study suggested that some gains, such as fewer people smoking and lower cholesterol rates, will be offset by the impact of obesity as many people who have been obese for long periods of their lives then reach old age.

However, tackling obesity – which is a major risk factor for many of the conditions described – could potentially have an impact in the future, the experts said.

Anita Charlesworth, director of the Real Centre (research and economic analysis for the long term) at the Health Foundation, said that, over the last 30 years, obesity levels in the adult population have broadly doubled.

“Some of this is almost certainly baked in and very difficult to change but, clearly when you look at things like type 2 diabetes, if people were to reduce their weight significantly after diagnosis of type 2, that can make a big difference to quality of life”, she told a briefing.

She added that, while the report looks at adults, there are “really concerning obesity rates” among children, which will have a big future impact on the NHS.

Ms Charlesworth said that, at present, 6% of the working age population are out of the labour market due to ill health but this will rise by an extra 500,000 people.

Conditions such as depression, anxiety and chronic pain affect those currently not working but it is known, for example, that access to mental health services is “very constrained” at the moment, she said.

The report warned: “There is no silver bullet to reduce the growth in the number of people living with major illness.

“A long-term plan is needed to reform, modernise and invest in the NHS, alongside a bold new approach to investing in the nation’s healthand wellbeing.”

For the study, researchers used health and death records to look carefully at the 20 health conditions that account for 65% of the burden of illness in England.

They also noted that life expectancy by 2040 is expected to rise to 83.1 years.

Only one out of 20 conditions listed – coronary heart disease – is expected to drop due to declining smoking rates and the use of medications such as statins.

This led researchers to conclude that almost one in five people will have a major illness by 2040, up from almost one in six in 2019.

Toby Watt, economist at the Real Centre, said: “The findings from this report give us new insight into the future demand for health care in England.

“It is crucial to emphasise that these are projections, not forecasts, which are designed to support policymakers in preparing for the future.

“The rise in people living with major illness will not occur overnight. Managing these pressures is achievable with careful planning, investment and changes in how care is delivered.”

Ms Charlesworth added: “Over the next two decades, the growth in major illness will place additional demand on all parts of the NHS, particularly primary care, where services are already under extreme pressure.

“But with one in five people projected to be living with major illness in less than two decades’ time, the impact will extend well beyond the health service and has significant implications for other public services, the labour market and the public finances.”

Miriam Deakin, director of policy and strategy at NHS Providers, said: “Prevention is better than cure. More support and money for public health services are vital to stave off poor health and ease pressure on the NHS.”

Dr Layla McCay, director of policy at the NHS Confederation, said: “With 80% of the projected increase in people living with major illness affecting those aged 70 and over, supporting the social care sector will be vital to ensure effective and safe care is provided to patients so they can continue to live a healthy and fulfilling life.”