A higher intake of fish oil may help you combat age-related loss of brain volume, possibly lowering your risk of developing Alzheimer’s disease and other types of cognitive decline, according to research from the University of South Dakota.

The new study, which is published in the journal Neurology, shows that high levels of omega-3 fatty acids commonly found in salmon, trout, sardines, and other fish correspond to a larger brain volume in old age. Dr. James V. Pottala, an assistant professor at University of South Dakota Sanford School of Medicine and lead author of the paper, said in press release that this discovery illuminates a simple and cost-effective way to fend off mental decline in old age. "These higher levels of fatty acids can be achieved through diet and the use of supplements, and the results suggest that the effect on brain volume is the equivalent of delaying the normal loss of brain cells that comes with aging by one to two years," he explained.

To investigate, Pottala and colleagues looked at data from the Women’s Health Initiative Memory Study — a previous longitudinal study aimed at assessing dementia factors in U.S. women over the age of 65. The team used MRI imaging to measure the brain volume of the participants, whose average age is now 78. These volumes were then matched checked against eight-year-old data indicating each participant’s omega-3 fatty acid levels.

The team found that women with high omega-3 fatty acid levels had significantly higher brain volumes eight years later. A value twice as high as the lowest quartile, for example, corresponded to a 0.7 increase in volume. In addition, women with high intake also saw an average volume increase of 2.7 percent in their hippocampus, a brain area thought to play an important part in short- and long-term memory, navigation, and other key faculties.

Fish Oil and Brain Size

Today, official estimates indicate rising rates of Alzheimer’s disease, with more than five million Americans living with the condition as of 2014. The most common form of dementia, Alzheimer’s disease is characterized by neurodegeneration — a harrowing process whereby nerve connections in the brain are gradually broken down. This typically results in a range of debilitating cognitive impairments, including confusion, disorientation, loss of motor skills, and memory loss. In turn, these symptoms generally bring with them a number of lifestyle changes as well as an increased risk of injuries.

The current study adds to the growing number of cost-effective preventative measures proposed in response to projected global rise in dementia cases. Scientific authorities believe that, as a consequence of better health care and rising life expectancies, the incidence of age-related dementia will have tripled by 2050. That means that the total number of patients will be driven up from 44 million to 135 million in less than four decades. "It's a global epidemic and it is only getting worse,” Marc Wortmann of Alzheimer’s Disease International (ADI) said, speaking to BBC News. “If we look into the future the numbers of elderly people will rise dramatically."

It follows that dementia prevention can no longer rely completely on primary physicians and neurologists. In 2014, efforts to rein in the incidence of such cognitive decline must occur on all levels, with at-risk demographics actively participating in everyday prevention strategies. It all starts with a sensible diet.

Source: Pottala JV, Yaffe K, Robinson JG, Harris WS et al. Higher RBC EPA + DHA corresponds with larger total brain and hippocampal volumes. Neurology. 2014.