Remember your mother telling you: "Eat your fish. It's good for your brain." She may just have been right. Scientists think they have evidence that fish oil could cure mental disorders such as depression and dyslexia - conditions increasingly common in the Western world. "This really does represent a breakthrough in the managing of individual depressions," Alexandra Richardson, Senior Neuroscience Research Fellow at Britain's University of Oxford, told a seminar about depression in Stockholm on Thursday. "If the brain does not have the right fats, it will not be working right." The right fats to beat the blues are large amounts of Omega-3 fatty acids, found in oily fish such as salmon and mackerel. Richardson's research found that the lack of these fats -- which are needed for the normal development and functioning of brain cells -- causes depression, autism, dyslexia and ADHD (attention-deficit hyperactivity disorder) in some people. Depression became increasingly common in the 20th century and one in four people will suffer from a mental or neurological disorder during their lifetime, according to World Health Organisation data. High levels of stress, alcohol, nicotine and caffeine consumption can further decrease the levels of fatty acids, aggravating or even creating mental disorders, Richardson said. She believes there is a link between the dramatic increase of depression and changing eating patterns in the West. "We really seem to be looking at a crisis here and it's all in the diet," she said. In countries where people eat less fish the increase in the incidence of depression is higher than in, for instance, Japan where fish consumption remains high, Richardson said. She said everyone could benefit from increasing their intake of Omega-3 fatty acids. "There is little too lose. There are hardly any negative side-effects, only nice cosmetic ones such as nice shiny hair, strong nails and healthy looking skin."