Age-related changes in non-cognitive behaviours in a canine model of aging and dementia and therapeutic evaluation of adrafinil and modafinil

The canine model of human aging and dementia has focused on cognitive aging with limited work on non-cognitive behaviours. The present investigation examined changes in non-cognitive behaviours in dogs as a function of age and cognitive ability. The therapeutic potential of two stimulants, adrafinil and modafinil, were also assessed.;Locomotor activity was assessed using the open field test, the home cage test and the ActiwatchRTM system. Age-dependent declines were observed in a familiar situation using both the home cage test and Actiwatch RTM system. Cognitively impaired aged dogs, however, showed increased activity compared to unimpaired dogs. Dogs raised in a laboratory setting were hyperactive compared to dogs raised on a farm.;The ActiwatchRTM demonstrated circadian patterns of activity in dogs that varied as a function of age, cognitive status and housing environment. Aged dogs housed in an indoor facility showed a delayed onset of activity and shorter, more fragmented bouts of activity compared to young dogs. Age-related differences were less prominent in dogs housed in an outdoor facility.;The human interaction, model dog and silhouette tests assessed social responses. Young dogs displayed more active social responses including climbing and licking. The aged dogs preferred more passive responses such as sitting quietly beside the person. Cognitively impaired dogs exhibited very little interest in the social stimuli.;Exploratory behaviour was assessed with the curiosity test. Interest in the toys declined with age with older dogs spending less time playing. Impaired dogs expressed little interest in the toys. Environmentally impoverished dogs showed high levels of interest in the toys independent of cognitive ability.;The mirror test most reliably distinguished between cognitively impaired and unimpaired aged dogs. Impaired dogs spent the most time reacting to the reflection compared to other dogs.;Adrafinil and modafinil are behavioural stimulants that we studied in aged dogs. Adrafinil most effectively increased locomotion in the novel open field test. Modafinil produced small increases in the open field test. No effect of modafinil was observed in the human interaction, curiosity or mirror tests.;The canine model of human aging and dementia can therefore be extended to include non-cognitive behaviours and used to evaluate the therapeutic potential of pharmaceuticals and dietary interventions.