By Katherine Sellgren
BBC News education reporter
Adult classes can range from art appreciation to gardening
Mental health is being put at risk as adult education classes are sidelined in favour of basic skills training.
A government report has found life-long learning to be an important way of guarding against mental illness.
But the National Institute of Adult Continuing Education (Niace) said 1.4 million fewer adult education classes had been taken in the past three years.
It said the drive to improve workplace skills in England had seen classes like art and languages decline rapidly.
Niace said Lord Leitch's review of skills in 2006 had led the trend to put resources towards skills training rather than other forms of adult education, such as evening classes.
The Foresight report recommends five ways to ward off mental illness:
CONNECT: with people around you
BE ACTIVE: exercise makes you feel good
TAKE NOTICE: of your surroundings and savour the moment
KEEP LEARNING: try something new or rediscover an old interest
GIVE: do something nice for a friend or a stranger
Associate director of Niace Stephen McNair said the government needed to acknowledge the benefits of all forms of adult education.
"There are clear benefits in terms of public health and social cohesion from life-long learning that are not recognised by the government," he said.
"Economic productivity isn't the only purpose of government - a part of government is to make sure people are happy and well and part of a cohesive society.
"What Niace would like to see is stronger recognition of the ways life-long learning contribute to mental health and capacity.
"The most obvious thing that makes people happy is being with other people and adult education is an important way of doing that, especially if they are not in employment."
Mr McNair cited retired people, women at home with small children, carers and those out of work as groups of citizens who could find adult education classes an important way of developing social links.
Niace hopes the findings of the Foresight report, which was sponsored by the Department for Innovation, Universities and Skills, will help boost the status of life-long learning.
The report said the UK needed a major rethink of workers' mental health amid the current economic uncertainty.
'Bank account of the mind'
In response the government's chief scientific adviser, Professor John Beddington, said mental capital could be likened to a bank account of the mind.
Speaking on BBC Radio 4's Today programme, Prof Beddington said this account could be neglected in a number of ways.
"Not being active, not connecting with people around you, not really taking much notice of what's going on around you and actually keeping learning.
"Learning is actually one of the things that is really seen to be very helpful, particularly in the elderly.
"Continuing learning right into later life is proving to be extraordinary successful, but relatively few people do that," he warned.
A spokesman for the department said the government was committed to supporting people of all ages to learn throughout their lives.
"This is precisely why we are investing more than ever in further education and an adult skill including £210 million for informal adult learning which we recognise contributes hugely well-being of individuals, neighbourhoods and wider society," he said.