Many older patients with common mental health problems are not being offered an effective form of treatment, experts have said.
The authors of a new study claim that elderly patients are being "under-referred" for talking therapies, despite evidence suggesting that they benefit more than younger ones.
Concerns about age discrimination for elderly patients seeking help for common mental health problems such as anxiety or depression have been widely shared, they said.
The researchers, led by Dr Sophie Pettit of the University of West London, launched a new study looking at the rates of referral for patients of different age groups.
Their study, published in the British Journal of General Practice, examined more than 80,000 referrals for patients from the South West of England.
They found that the proportion of patients being identified with common mental health problems peaks for patients aged 20 to 24 where 23% are referred for talking therapies.
This "reduces with increase in age", they said.
Just 6% of 70 to 74-year-olds were referred for talking therapy, they found.
The researchers also looked at patient outcomes and found that the proportion of those showing clinical improvements increases with age.
Meanwhile, they also found that older patients were more likely to actually keep their appointments compared to younger ones.
"The results show that older adults with common mental health problems are being under-referred but benefit more than younger individuals once they obtain access to the service," the authors wrote.
They added: "Concerns about discrimination against older adults leading to reduced access to talking therapies have been widely shared.
"The current study has shown, taking estimated prevalence into account, that access is indeed lower for older and middle-aged adults compared with younger adults."
Dr Amanda Thompsell, chairman of the Old Age Faculty at the Royal College of Psychiatrists, said: "This report shows clear discrimination against older people when it comes to talking therapies.
"In 2009 we warned that tens of thousands of over-65s with common mental health problems risked missing out on vital support because access to some services was arbitrarily set at 65 years old.
"Many of the barriers deterring access to the elderly remain: from a lack of provision for home visits or transport to and from appointments, to problems using the internet and their generation's stoical belief in just getting on with things.
"This report's helpful suggestion is that GPs should try to raise the awareness of their elderly patients of the talking therapies available and their potential benefits.
"Until they get this message across and the practical barriers to accessing talking therapies are overcome, this blatant discrimination will remain."
Commenting on the study, Professor Helen Stokes-Lampard, chairwoman of the Royal College of GPs, said: "Mental health issues can affect anyone at any age, and all our patients deserve high quality mental health care at every stage of their life.
"We know that access to certain therapies, such as talking therapies, can really benefit some patients with mental health conditions - particularly our older patients, as highlighted in this study - so it's concerning that as our patients get older, they are experiencing greater difficulty in accessing them.
"Unfortunately, it is increasingly the case that these important services aren't readily available in the community, where they would be of most benefit, so GPs simply cannot refer our patients onto them when they need them, or patients face significant delays even when they are referred.
"We need more mental health services in the community. We need a greater variety of services in the community and we need GPs and our teams to have better, easier and quicker access to them."
Nia Charpentier, of the charity Rethink Mental Illness, said: "Mental illness doesn't discriminate. It can affect anyone at any time in our lives.
"Getting the right help and support without delay can make a huge difference in someone's ability to live the best possible quality of life, no matter what their age.
"That's why it's worrying to hear that so many older people with mental health problems are missing out or being cast aside when it comes to accessing treatment.
"To address this situation, it's important to understand and tackle the different barriers someone may face when accessing treatment, whether that's long waiting lists, a lack of mental health services in the community, or a reluctance to seek help in the first place.
"However, the bottom line is that there is still an urgent need for more funding and better-designed mental health services, to guarantee fair access to support and treatment for anyone who may need it."