This study focused on the hypothesis that cognitive decline in aged dogs could be attenuated by dietary supplementation with a nutrient blend consisting of antioxidants, B vitamins, fish oil and l-arginine, referred to hereafter as the Brain Protection Blend (BPB). Baseline cognitive assessment before the start of treatment was used to establish cognitively equivalent control (10·464+2·33 kg) and treatment (12·118+3·386 kg) groups of aged dogs between 9·1 and 11·5 years of age and with body condition score of 5. After an initial wash-in period, all dogs were tested over a 6-month period on cognitive test protocols that assessed four phases of a landmark discrimination learning protocol, which assessed a spatial learning skill based on utilisation of external cues, and egocentric discrimination task, which assessed spatial learning based on internal body-centred cues. The BPB-supplemented group showed significantly better performance than the controls on the landmark 1 (P=0·0446) discrimination learning tasks, and on two egocentric discrimination reversal learning tasks (P=0·005 and P=0·01, respectively). The groups did not differ significantly (P>0·10) on the landmark zero discrimination task and the egocentric discrimination learning task. These results suggest beneficial effects are positively linked to task complexity. Many of the nutrients supplemented in the BPB diet were significantly higher in plasma, including arginine, α-tocopherol, DHA and EPA. These results indicate that long-term supplementation with the BPB can have cognition-improving effects and support the use of nutritional strategies in targeting brain ageing-associated risk factors as an intervention to delay cognitive ageing.

Cognitive dysfunction syndrome is a major disease affecting old cats and is the consequence of severe and irreversible loss of brain cells and brain atrophy. The present study focused on the hypothesis that the optimal strategy for promoting successful brain ageing is to target risk factors associated with brain ageing and dementia. We used a nutritional strategy involving supplementation with a blend of nutrients (antioxidants, arginine, B vitamins and fish oil) to test this hypothesis. Middle-aged and old cats between 5·5 and 8·7 years of age were assigned to cognitively equivalent control or treatment groups based on prior cognitive experience and performance on baseline cognitive tests. The cats in the treatment group were maintained on a diet supplemented with the nutrient blend and the cats in the control group were maintained on the identical base diet without the additional supplementation. After an initial wash-in period, all cats were tested on a battery of cognitive test protocols. The cats fed the test diet showed significantly better performance on three of four test protocols: a protocol assessing egocentric learning, a protocol assessing discrimination and reversal learning and a protocol focused on acquisition of a spatial memory task. The results support the hypothesis that brain function of middle-aged and old cats can be improved by the nutrient blend that was selected to minimise or eliminate the risk factors associated with brain ageing and dementia.