Nutrients, Cognitive Function, and Brain Aging: What We Have Learned from Dogs

Abstract

Due to a difference in genetics, environmental factors, and nutrition, just like in people, dogs age at different rates. Brain aging in people and dogs share similar morphological changes including irreversible cortical atrophy, cerebral amyloid angiopathy, and ventricular enlargement. Due to severe and irreversible brain atrophy, some aging dogs develop cognitive dysfunction syndrome (CDS), which is equivalent to dementia or Alzheimer’s disease (AD) in people. The risk factors and causes of CDS in dogs have not been fully investigated, but age, gender, oxidative stress, and deficiency of sex hormones appears to be associated with increased risk of accelerated brain aging and CDS in dogs. Both AD and CDS are incurable diseases at this moment, therefore more efforts should be focused on preventing or reducing brain atrophy and minimizing the risk of AD in people and CDS in dogs. Since brain atrophy leads to irreversible cognitive decline and dementia, an optimal nutritional solution should be able to not only enhance cognitive function during aging but also reduce irreversible brain atrophy. Up to now, only one nutritional intervention has demonstrated both cognition-enhancing benefits and atrophy-reducing benefits.

Relação entre a gonadectomia e o déficit cognitivo em Canis lupus familiaris

“…Este hormônio aparenta potenciar a aprendizagem e a memória, mantendo o circuito neuronal do córtex frontal e do hipocampo, ao mesmo tempo que a testosterona em machos não castrados parece retardar o declínio cognitivo em cães que já possuem sinais deficitários 41 .…”

Imbalance in the ratio between mineralocorticoid and glucocorticoid receptors and neurodegeneration in the dentate gyrus of aged dogs

“…The AG group presented a higher number of degenerating neurons (positive fluoro-Jade B staining) in the polymorphic layer, decreased MR expression, and a tendency to have fewer cells in this region. Neuronal loss in the dog's brain is present in the elderly [14,15,24], and it is a possible cause of atrophy of the hippocampus and other CNS regions found in aged dogs [14]. Accordingly, researchers have identified age-related changes in hippocampal anatomy, such as reducing the height of the hippocampal formation in aged dogs using magnetic resonance imaging [34].…”

“…The aging of a dog's central nervous system (CNS) is associated with cognitive decline and neuropathological changes, similar to humans [9,14,24,25]. Given the increased canine life expectancy and the neurodegenerative processes associated with aging [24,26], such as neuronal loss [14], it is critical to study the neuropathological processes in aged dogs in different breeds that are part of the clinical routine. In this way, it would be possible to understand under what conditions the CNS of this species is subjected to aging.…”

Investigating Owner Use of Dietary Supplements in Dogs with Canine Cognitive Dysfunction

“…In the absence of glucose, e.g., in periods of starvation, the brain relies on alternative energy sources such as ketone bodies derived from triglyceride metabolism [19][20][21]. These ketones are an important energy source for the aging brain as well, as aging can cause mitochondrial dysfunction and glucose hypometabolism [12,[22][23][24] which can lead to oxidative stress and free radical damage associated with cognitive impairment [17].…”