Let's talk about Cognitive Dysfunction Syndrome in animals and see how to prevent its development and slow down its progress.
Cognitive Dysfunction Syndrome (CDS) is a progressive neurodegenerative disease that can occur in dogs and cats and has many similarities to Alzheimer's disease in humans. The main characteristic is the progressive reduction of cognitive functions, such as learning, memory, perception and consciousness, and is observed in dogs over seven years of age. Some studies describe a prevalence ranging from 14.2% to 68% in geriatric dogs, while the prevalence in cats over 11 years of age is around 35%.
Morphologically, there is a decrease in brain mass, mainly in the frontal cortex, as well as other changes such as an increase in ventricular volume, meningeal thickening, changes in the myelin sheath, accumulation of macrophages and loss of neurons in the hippocampus, a region of the brain responsible for memory and localization. Elderly cats affected by CDS also show brain atrophy, neuronal loss, widening of the sulci, a decrease in the volume of gray and white matter, although to a lesser extent than in dogs.
At a biochemical level, there is an accumulation of beta-amyloid protein plaques, which is neurotoxic, leading to inflammatory alterations, neurotoxicity and oxidative stress. In canines, there is a reduction in cholinergic function and oxidative damage, while in felines, the atrophy of the cholinergic system is more marked and the deposition of beta-amyloid protein is less obvious.
The structural pathological alterations observed in the central nervous system of dogs with CDS are similar to the lesions observed in humans with Alzheimer's disease, but this denomination is not applied to characterize the disease in animals, since although they present diffuse amyloid plaques, they do not develop the typical neurofibrillary tangles (NFT) of this disease, observed in the human brain. However, accumulations of hyperphosphorylated protein, known as tau protein, which is a precursor of NFTs, can be found.
Among the most characteristic clinical signs are disorientation, changes in behavior with decreased interest in social interactions or development of dependent behaviors. In addition, changes in the sleep/wake cycle, eliminations in inappropriate places, changes in activity level, decreased appetite and increased anxiety are also commonly observed. It is important to understand that this syndrome is NOT an inevitable consequence of aging in dogs and cats. Some elderly animals show only mild signs, while others develop more severe signs, which can include a decline in consciousness, altered response to stimuli, deficits in learning and memory and reduced interaction with guardians, leading to a reduced quality of life.
Providing elderly dogs and cats with environmental enrichment, social interaction, play and cognitive training, along with an appropriate nutritional base, contributes to the maintenance of neurons and, consequently, brain health. Thus, early detection and intervention of the problem can slow cognitive decline, avoiding complications, increasing longevity and improving your pet's well-being.
There are some therapeutic strategies that can help with cognitive dysfunction in dogs and cats, starting with diet and supplements that can reduce the risk factors that contribute to brain ageing and cognitive decline. A holistic approach is needed to achieve and maintain brain health, such as diets supplemented with polyunsaturated fatty acids, antioxidants and mitochondrial cofactors.
There is a huge range of nutraceuticals and supplements that can help prevent and treat CDS in animals. Just to name a few, we have PEA (Palmitoylethanolamide), phosphatidylserine, Gingko biloba, Bacopa Monnieri, vitamins E, B6, and C, Resveratrol, which can be used in both dogs and cats. Vitamin C, L-carnitine, alpha lipoic acid, coenzyme Q-10 and selenium are also good options for these animals. There are also various medicinal mushrooms, notably Hericium (known as "Lion's Mane"), Ganoderma ("Reishi") and Cordyceps Sinensis. Below, we'll explain some of them in a little more detail:
PEA (Palmitoylethanolamide): I've talked about PEA on other occasions, including in the article on eye health. With regard to the nervous system, it is able to modulate the activity of glial cells and mast cells, making it a very promising therapeutic tool for treating neurological disorders. PEA has the ability to modulate the reactivity of these cells, limiting the release of pro-inflammatory and neurotoxic mediators and favoring neuronal survival. In addition, PEA increases levels of 2-AG (2-arachidonoylglycerol), the concentration of which decreases with with advanced age, especially in the hippocampus. An increase in 2-AG in the hippocampus improves synaptic plasticity and mnemonic and cognitive performance.
Polyunsaturated fatty acids (PUFA): As the brain is very vulnerable to oxidative stress due to its high oxygen consumption (it consumes 20% of the body's total oxygen) and given that in the aging brain, excess generation of free radicals leads to neuroinflammation, omega-3 fatty acids are very useful, especially DHA and EPA. They are important for structuring the cell membranes of neurons and physiological functions in the brain.
Curcumin: This nutraceutical has also been mentioned in other articles on my Blog. It has anti-inflammatory, antioxidant, cytoprotective, neutroprotective effects and prevents the increase in beta-amyloid protein. It reduces the degeneration of neurons and fights inflammation of the microglia, which are the cells in the CNS responsible for immune defense.
Bacopa Monnieri: This is a plant used in Ayurvedic medicine, with brain tonic properties, among others. It stimulates memory and mental clarity and has benefits for neuronal activity. It increases acetylcholine levels, which is useful for cognitive disorders and acts on GABA and serotonin. It increases dendritic connections between neurons, repairs synapses and damaged neurons. It is also able to reduce the deposition of beta amyloid substance and increase cerebral blood flow.
Phosphatidylserine: a phospholipid that forms part of the cell membrane, facilitating the normal functioning of neuron cell membranes and influencing various neurotransmitters. Phosphatidylserine supplementation can reduce memory loss and the progression of CDS.
Ginko Biloba: Inhibits apoptosis induced by beta-amyloid proteins in the hippocampus, acting as a neuroprotector, improving mitochondrial metabolism and ATP production. It also activates anti-platelet factors and improves cognition and memory.
Resveratrol: Has antioxidant and anti-inflammatory effects, as well as improving mitochondrial function and acting as a neuroprotector, preventing memory loss.
Medium-chain triglycerides (MCTs): studies show that long-term supplementation with MCTs, such as coconut oil, improved cognitive function in elderly dogs. They improve mitochondrial function and increase ATP (energy) production, as well as reducing the deposition of beta-amyloid proteins.
It can therefore be concluded that although a high percentage of elderly dogs and cats can be affected by CDS, there are several nutraceuticals which, combined with a healthy lifestyle and physical exercise, can help with prevention and treatment, improving or restoring cognition and memory.
But beware!
Nutraceuticals and other supplements, as well as any medication for your pet, should be prescribed by a veterinarian, as there are correct doses and the most suitable medication for each patient!
References:
GUPTA, R. et al. Nutraceuticals for Cognitive Dysfunction. In: Nutraceuticals in Veterinary Medicine. Springer Nature Switzerland AG, 2019, pp. 393-416.
LANDSBERG, G. Cognitive dysfunction in Aged Cats and Dogs. In: Ettinger S. et al. Textbook of Veterinary Internal Medicine. Elsevier. 8th ed. 2017, pp.1414-1417.
MIHEVC, S.; MAJDIK, G. Canine Cognitive Dysfunction and Alzheimer’s Disease – Two Facets of the Same Disease? Frontiers in Neuroscience, Vol. 13, Article 604, June, 2019. pp.1-18, doi: 10.3389/fnins.2019.00604.
PERO, M.E. et al. Effects of a Nutritional Supplement on Cognitive Function in Aged Dogs and on Synaptic Function of Primary Cultured Neurons. Animals 2019, 9, 393; doi:10.3390/ani9070393
SCUDERI, C. & GOLINI, L. Successful and Unsuccessful Brain Aging in Pets: Pathophysiological Mechanisms behind Clinical Signs and Potential Benefits from Palmitoylethanolamide Nutritional Intervention. Animals 2021, 11, 2584.
SUKUMARAN, N.P. et al. Neuropharmacological and cognitive effects of Bacopa monnieri (L.) Wettst – A review on its mechanistic aspects. Complementary Therapies in Medicine, Volume 44, June 2019, Pages 68-82
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