It amounts to £1.5m in the UK and $2.4m in the US for individuals with the highest needs, say UK and US experts.
Autism cost the UK more than heart disease, stroke and cancer combined, said an autism charity.
But only £6.60 per person is spent on autism research compared with £295 on cancer, according to Autistica.
The research looked at the costs to society of autism spectrum disorders (ASD) in both the UK and US.
Autism cost the UK at least £32bn a year in terms of treatment, lost earnings, and care and support for children and adults with ASD, found the study, published in the Journal of the American Medical Association Pediatrics.
This compared with £12bn for cancer, £8bn for heart disease and £5bn for stroke, said Autistica.
The figures showed a clear need for more effective interventions to treat autism, ideally in early life, to make the best use of scarce resources, said lead researcher Prof Martin Knapp, of the London School of Economics and Political Science, in London.
"We need to use our resources earlier, identify people earlier and try to provide therapies and support that makes it easier to manage the condition," he told BBC News.
He said new government policies were also needed to address "the enormous impact on families".
Christine Swabey, chief executive of the autism research charity, Autistica, said there was an "unacceptable imbalance" between the high cost of autism and the amount spent on research.
"The right research would provide early interventions, better mental health, and more independence," she said.
"But right now we spend just £180 on research for every £1m we spend on care."
Commenting on the study, Prof Emily Simonoff, of King's College London's Institute of Psychiatry, said the finding was important because of the "relatively low amounts of research funding that go to mental health, despite its huge burden".
More than 600,000 people in the UK have autism, a developmental disorder that can cause problems with social interaction, language skills and physical behaviour.
The disorder varies from mild to so severe that a person may be unable to communicate and need round-the-clock care.
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VJ Day on 15 August 1945 followed the destruction of Hiroshima and Nagasaki by atomic bombs.
On Saturday, services have been held at St John's Church in Cardiff and at the war memorial in Llandudno, Conwy.
A national service is taking place at Llandaff Cathedral on Sunday where First Minister Carwyn Jones will give a reading.
The Cardiff Branch of the Burma Star Association has held its service at St John's Church.
About 300 people joined the parade from Llandudno Pier Head to the war memorial where a drumhead service was placed.
Canon of Dr Sarah Rowland Jones, from St John's Church, said: "The Burma Star Association was set up in 1951, and ever since we've had the veterans coming and holding a service annually.
"They're now down to single figures, only a couple of them are hail and hearty in their mid-90s and so they decided the time had come on the 70th anniversary of VJ Day to lay up their standard.
"So what we are doing today is holding a service in which the standard will be paraded as usual but at the end of the service it will be handed over to the church's safe keeping and we shall we hanging it up permanently right next to the Burma Star window so that it can be there for future generations to look at and be prompted to remember."
The national service the following day, which is open to the public and has been organised by the Welsh government, Cardiff council and Llandaff Cathedral, will start at 15:30 BST.
Speaking ahead of the event Mr Jones said: "We must never forget the sacrifice allied forces made for our freedoms during World War Two.
"Victory in Japan by the allied forces brought to an end six years of conflict which saw the tragic loss of so many lives and the destruction of so many communities across the world.
"Their heroics in battle, often so very far from home, will always have a special place in our hearts and it's important we remember and show our gratitude for their service."
The economic cost of supporting someone with autism over a lifetime is much higher than previously thought, research suggests.
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Commemorations have taken place across Wales to mark the 70th anniversary of Victory in Japan day.