Richard Williams, head of the Royal College of Psychiatrists in Wales, says children have not been immune to fallout from the crisis.
Dr Williams said children, as well as adults, are susceptible to stress arising from a drop in disposable family income, unmanageable debt, housing problems and social deprivation.
"Children are much more aware than adults think they are - they may not voice it at home for fear of causing more trouble, but often they worry about impacts on parents, especially when they see their behaviour change," Dr Williams said.
"Their need for reassurance goes up at the very point when the adults are preoccupied with their own survival, and their ability to cope with the needs of their children are eroded."
He said governments grappling with the effects of the GFC should funnel money into mental health programs for young people now to avoid problems down the track.
"Governments on the brink of financial calamity would be well advised to shunt money into mental health in advance, knowing that they would get it back later," he told AAP.
"I would expect to see ... a lag period while the troubles are at their most acute and people are doing their best to cope, but after a period of erosion we'll see more anxiety and depression among kids.
"We may see an increase in conduct disorders - that's not just bad behaviour, that's children that are showing their problems through bad behaviour."
Dr Williams said the average depression rate for children was four per cent, but this was only the tip of the iceberg as many children remained undiagnosed.
"That's people who actually reach diagnosis," he said.
"In the UK we estimate 18 per cent more kids have sub-threshold problems."
He said that if parenting programs were implemented over 25 years, the gross savings would exceed costs by a factor of eight to one.
"Between a third and one half of all adult problems begin in childhood and adolescence," he said.
"If we could nip that in the bud, societies would be much more productive, but that's very hard to tell the authorities, as the financial impacts are falling on societies now."
Dr Williams will discuss the impact of the GFC and austerity measures on mental health at the Royal Australian and New Zealand College of Psychiatrists child and adolescent psychiatry conference in Sydney on Thursday.