Dogs, just like humans, can have problems with learning, memory and attention, particularly as they get older. Several tests of cognitive ability in dogs have been used in research with a particular focus on the effects of ageing. What is less well understood is how diseases affect these cognitive abilities. In an article in CAB Reviews, Lena Provoost, Margret Casal and Carlo Siracusa discuss how changes in behaviour, such as loss of appetite, house soiling or changes in sleeping are often the first indicators to the pet’s owners that there is a problem. The team from the School of Veterinary Medicine at the University of Pennsylvania say that while those changes could be caused by mental decline, they could be secondary effects of other medical causes, such as pain from infection swellings or kidney disease.
It’s well known that omega-3 fatty acids are crucial to the development of the brain. Animal studies have suggested that a specific fatty acid, docosahexaenoic acid (DHA), plays a role in the development of cognitive abilities. So will taking extra DHA as a child make you cleverer? A paper in CAB Reviews by Carol Cheatham at the University of Kansas Medical Center looks at the evidence from both animal and human studies.
Animal studies have shown clearly that DHA deficiency affects memory and learning, and that providing extra DHA can restore these abilities to some extent. However, in humans, fewer than half the randomised clinical trials report effects on cognition from DHA.
Babies born early miss out on the final weeks of DHA they would receive from their mothers via the placenta. Studies show that providing preterm babies with DHA does improve memory and attention relative to controls. However, for babies born at term, providing extra DHA has not given the same clear outcome, with different trials giving different results.
Cheatham looks at three possible reasons. One is that the doses of DHA may not have been high enough to work. Also, the trials used a wide variety of measures of learning and memory. Looking at more specific measures of cognition could give less mixed results. Few studies have looked at the long- term impacts, and so studying children some years after taking DHA supplements in more sophisticated tests may reveal differences.
The paper,Omega-3 fatty acids and the development of cognitive abilities: a review of DHA supplementation studies, by Carol L. Cheatham appears in CAB Reviews: Perspectives in Agriculture, Veterinary Science, Nutrition and Natural Resources, 2008, 3, No. 001.