They analysed lifestyle and health patterns of more than 10,000 people in the US and Britain and their links to participants' mental and physical quality of life and health status, the European Journal of Epidemiology reported.
Saverio Stranges, who led the study at Warwick, with Kandala Ngianga-Bakwin, said: "It's obvious that people's physical quality of life deteriorates as they age, but what is interesting is that their mental well-being does not deteriorate - in fact, it increases."
Quality of life was evaluated using a measure which takes in eight different factors, including perception of general health, pain, social functioning and mental health, according to a university statement.
This is in line with previous research, for example by Andrew Oswald, professor at Warwick, which suggests that happiness levels follow a U-shape curve with their lowest point in the mid-40s after which they rise as people move into older age.
Supportive results were found in this cross-cultural comparison study in the US and Britain - two countries which have different welfare and health-care systems, factors which could impact on people's quality of life.
Researchers also found that being overweight or obese did not have a significant impact on mental well-being levels, with people having a body mass index (a height to weight ratio) of more than 30 showing similar mental quality of life levels to those considered to be a healthy weight.
For women in the US, low levels of physical exercise did not appear to impact on their mental well-being. This was not the case for men, where limited physical exercise had a significant adverse impact on their mental quality of life.