Local governments should now begin to invest more time and money in creating greener spaces (parks and gardens) within cities and towns as they fuel sustained improvement in mental health, according to a University of Exeter study.

For the study, the researchers analysed data from the British Household Panel Survey that followed over 1,000 participants for a five year period.

Researchers from the Medical School then concentrated on two groups of city-dwellers within the data: those who located to greener urban areas and those who shifted to concrete jungles.

They found that inhabitants of green areas gained the benefits of mental well-being immediately and the effect lasted for a minimum of 3 years even after they moved out. On the other hand, participants, who relocated to lesser green urban areas, suffered lower mental health before they shifted. However, the levels returned back to normal once they settled in their new location.

The findings suggest that the second group of people did not experience any improvements in mental health at all.

"We've shown that individuals who move to greener areas have significant and long-lasting improvements in mental health. These findings are important for urban planners thinking about introducing new green spaces to our towns and cities, suggesting they could provide long term and sustained benefits for local communities," Dr Ian Alcock, lead researcher of the study, said in a statement.

The finding could lead to the inclusion of more parks and gardens in future construction ventures.

According to the World Health Organisation, depression is the leading cause of disability worldwide. The findings support previous studies that show how natural environments help enhance quality of life, health and well-being in individuals.

The study has been published in the journal of Environmental Science & Technology.