Nutritional Support for the Aging Canine Brain

Discover how you can help your dog stay mentally fit with age.

Does your senior dog ever appear disoriented, confused or agitated? Does he sleep most of the day and pace at night? Does he seem withdrawn and stare into space or at a wall? Has he begun to soil the house without a medical cause? If so, he could be suffering from age-related cognitive decline, or “doggy dementia.”

Studies indicate that 20% – 30% of dogs older than 7 – 9 years of age suffer from some level of cognitive dysfunction, while that number rises to 68% in dogs older than 14 years.^[1]

Senior dogs can suffer from degenerative cognitive effects similar to Alzheimer’s disease in people, known as Canine Cognitive Dysfunction (CCD) or Cognitive Dysfunction Syndrome (CDS). As in people, CCD in dogs can range from mild cases to severe dementia, and typically becomes progressively worse with time.

Dogs with CCD may experience a variety of symptoms, including:

• Agitation and anxiety
• Aggression
• Compulsive licking
• Confusion
• Decreased appetite
• Decreased memory
• Destructiveness
• Disorientation
• Disrupted sleep patterns
• Excessive vocalization
• Fear
• House soiling
• Hyper-vigilance
• Impaired learning ability
• Increased sensitivity to sound
• Lethargy
• Night-time waking and anxiety
• Noise phobias
• Over-attachment
• Pacing
• Reduced sociability
• Restlessness
• Salivation
• Separation anxiety
• Wandering^[2][3][4][5]

But there is good news. Similarities between humans and dogs have enabled researchers to apply information learned in people to also help our senior canine companions.^[1] Researchers now know more about the causes of age-related cognitive decline than ever before, as well as dietary nutrients and nutraceuticals that are clinically proven to help keep your dog’s brain functioning optimally well into his senior years.

Free Radicals and Cognitive Decline

Increased oxidative damage to the brain is suspected as a key factor in age-related diseases, including CCD. As I discussed in Part 1 of this two-part series, oxidative stress is a state in which the body produces more free radicals than it can detoxify.^[6]

Free radicals are atoms, or groups of atoms, with an unpaired, or “free”, electron. These unstable molecules go looking to “steal” an electron from other molecules in the body in order to stabilize themselves.^[7]

There are many types of free radicals, however most contain oxygen and are known as reactive oxygen species (ROS). ROS are constantly generated as by-products of normal processes that are essential to life. For example, the body produces free radicals when sugars are burned for energy and when digestive enzymes are released to break down food. White blood cells even produce oxygen radicals as part of the immune system’s response to kill invading pathogens.^[8]

Free radicals can also occur due to pathological processes. For example, cells that have a deficiency of oxygen (hypoxia) or those that have too much oxygen (hyperoxia) generate ROS. Free radicals are also generated due to sources outside the body, for example when breaking down certain medicines or from exposure to environmental pollutants, pesticides, cigarette smoke or radiation.^[9][10]

The Problem with Free Radicals

The problem is that free radicals are highly unstable and reactive, making them toxic to cells. Oxidative damage occurs when free radicals attack and damage a variety of important molecules inside cells, including DNA, proteins and lipids.^[9]

One of the most well known toxic effects of free radicals on cells is lipid peroxidation. Lipid peroxidation occurs when free radicals steal electrons from lipids (fats) in the cell membrane, damaging the membrane.^[8]

Cells that have been damaged by free radicals may not function properly or my even die.^[11] Damage from free radicals accumulates over time, creating progressively worsening changes.^[9]

The brain is especially vulnerable to damage from free radicals for several reasons, including:

• The brain has a high rate of oxidative metabolism, a chemical process in which oxygen is used to make energy from carbohydrates (also called aerobic metabolism).
• The brain has a high lipid content,^[1] thus making it especially vulnerable to lipid peroxidation).
• Left unprotected, oxidation in the brain can cause damage and even death of neurons, resulting in a decline in cognitive function.^[4]

Preventing Oxidative Damage with Antioxidants

Fortunately, the body is able to use antioxidants to scavenge free radicals and combat the effects of oxidative damage. Antioxidants are man-made or natural substances that may prevent or delay some types of cell damage.^[12]

Examples of antioxidants include:

• Beta-carotene
• Lutein
• Lycopene
• Selenium
• Vitamin A
• Vitamin C
• Vitamin E^[12]

Numerous studies show that a diet rich in antioxidants can help counteract the effects of free radicals on the brain, and that senior dogs fed an antioxidant-rich diet experience improved cognitive function. Not surprisingly, the benefits were even greater when behavioral enrichment was added to the protocol. ^[1][13]

In one successful long-term study (2.69 years), 24 Beagles ranging in age from 8.05 to 12.35 years at the start of the study received the following daily doses of antioxidants:

• 21 mg/kg/day of vitamin E
• 1.6 mg/kg/day of vitamin C
• 5.2 mg/kg/day of acetyl-l-carnitine
• 2.6 mg/kg/day of lipoic acid
• A mixture of fruits and vegetables were also incorporated into the dogs’ diets.^[13]

In another study, scientist Carl Cotman from the University of California’s Institute of Brain Aging and Dementia fed aged Beagles a diet rich in antioxidants. After six months on the antioxidant-rich diet, the dogs showed considerable improvement in cognitive function.^[2]

Cotman and his colleagues fed their dogs the following:

• Vitamin C
• Vitamin E
• Alpha-lipoic acid
• L-carnitine
• A mixture of fruits and vegetables to reduce free radical damage^[2]

Other studies also support the beneficial effects of an antioxidant-rich diet on the cognitive ability of senior dogs. One group of researchers concluded that:

The most important aspect of this work is the discovery that cognitive performance can be improved by dietary manipulation. Furthermore, the effects of the dietary manipulation were relatively rapid. Antioxidants may thus potentially act to prevent the development of these age-associated behaviors, and possibly even neuropathologic change, by counteracting oxidative stress.^[4]

Foods Rich in Antioxidants

Scientists at the United States Department of Agriculture (USDA) analyzed and ranked more than 100 different foods according to their antioxidant levels as measured by the food’s antioxidant concentration and antioxidant capacity per (human) serving size.

Fruits containing the highest antioxidant levels were cranberries, blueberries and blackberries. Beans, artichokes and Russet potatoes took top spot among the vegetables.

Following is the list of the top ranked dog-friendly foods in order of their antioxidant capacity:

Food item Serving size Total antioxidant capacity per serving size
1 Small Red Bean (dried) Half cup 13,727
2 Wild blueberry 1 cup 13,427
3 Red kidney bean (dried) Half cup 13,259
4 Pinto bean Half cup 11,864
5 Blueberry (cultivated) 1 cup 9,019
6 Cranberry 1 cup (whole) 8,983
7 Artichoke (cooked) 1 cup (hearts) 7,904
8 Blackberry 1 cup 7,701
10 Raspberry 1 cup 6,058
11 Strawberry 1 cup 5,938
12 Red Delicious apple 1 whole 5,900
13 Granny Smith apple 1 whole 5,381
17 Russet potato (cooked) 1 whole 4,649
18 Black bean (dried) Half cup 4,181
20 Gala apple 1 whole 3,903^[14][15]

More Brain-Boosting Foods

While antioxidants are powerful nutritional tools to combat free radical damage and oxidative stress, other foods also offer important brain-boosting benefits. The following are some of the best-studied foods to improve cognitive function:

Coconut Oil

Once vilified as an unhealthy saturated fat, coconut oil actually possesses many therapeutic qualities, but perhaps the most amazing is its scientifically proven ability to improve brain function in older dogs and people. What makes coconut oil different? Most fats are long-chain triglycerides (LCTs), a designation that refers to the length of the carbon chain making up the fatty acids. Coconut oil, however, is a medium chain triglyceride (MCT) made up of shorter carbon chains. This is important because MCTs are digested, absorbed and utilized by the body much more quickly, easily and efficiently than LCTs. MCTs bypass the normal (and rather laborious) method of fat digestion and are instead absorbed directly into the bloodstream, where they supply a rapid form of non-carbohydrate energy.

Since older brains are less effective at metabolizing glucose for energy, MCTs provide an alternate source of rapidly available energy for use by the brain. Supplementation with MCTs also improves mitochondrial function in the brain, increases the brains’ polyunsaturated fatty acids, and decreases amyloid precursor proteins (deposits found in the brains of Alzheimer’s patients) in the parietal cortex of older dogs.^[16]

As the body’s supercomputer, the brain requires a lot of energy, most of which is satisfied when the body breaks down glucose from food. However, as we age, we metabolize glucose less efficiently, leaving a gap in the brain’s energy requirement. When this occurs, alternative sources of fuel become important to fill this gap and provide much-needed energy to the brain. This is where MCTs, such as those found in coconut oil, can help save the day.

Additional benefits of MCTs include:

• MCTs readily cross the blood-brain barrier, supplying up to 20% of a normal brain’s energy requirement.
• MCTs are important for ketone production, which serve as an additional source of “brain food.”
• MCTs help the body use omega-3 fatty acids more efficiently and increase omega-3 concentrations in the brain (a good reason to give your dog both omega-3s and coconut oil).^[17][1]

One study showed that when 24 Beagles who were between the ages of 7.5 and 11.6 years old at the start of the trial were fed a diet supplemented with 5.5% medium chain triglycerides, their cognitive ability improved significantly. The dogs showed improvement in learning-related tasks after only about two weeks of consuming the supplemented diet, and within one month their learning ability improved significantly. The authors concluded that supplementation with MCTs can improve age-related cognitive decline by providing an alternative source of brain energy.^[18]

The coconut oil you select should be unrefined (virgin) and expeller pressed or cold pressed. If possible, choose organic brands to avoid potential contamination from pesticides. Coconut oil does not need to be stored in the refrigerator, but since it is light sensitive (like all oils), it’s best to keep it in a dark cupboard. Dark glass containers are excellent storage choices, as they protect the oil from light while also ensuring that no harmful BPAs leech into the product.

There are many ways to incorporate coconut oil into your dog’s diet. Try mixing a tablespoon into some goat or sheep’s milk yogurt or adding a dollop on top of some fresh organic blueberries. You can even scoop it straight from the container and let him lick the spoon. Dogs love the taste!

Studies show that coconut oil fed as 10% or less of your dog’s diet poses no digestive or other health issues.^[17]

Omega-3 Fatty Acids

About 20% of the brain’s cerebral cortex (the outermost layered structure of neural tissue) is made up of DHA, which also provides structural support to neurons (the cells that make up the central nervous system). Studies in people show that supplementation with DHA is beneficial in supporting cognitive health in aging brains and that inadequate levels can cause neurons to become stiff, hindering proper neurotransmission both within cells and between cells.^[19][20]

In elderly people, low levels of plasma DHA are associated with cognitive decline in both healthy individuals as well as those suffering from Alzheimer’s disease, while higher DHA levels are associated with a decreased risk of Alzheimer’s. In one study, patients who supplemented with DHA for 24 weeks showed improved learning and memory function associated with age-related cognitive decline. This means that supplementing with DHA does not only work to prevent age-related cognitive decline; it can also reverse the symptoms.^[19][20]

A study of 48 Beagle puppies showed that dietary fortification of fish oil rich in DHA following weaning resulted in improved cognitive learning, memory, psychomotor, immunologic and retinal functions during the developmental stage.^[21]

I recommend to my clients and give my own beloved boy, Chase, Nordic Naturals Omega-3 Pet. They also have a liquid version and special formulations for small breed dogs (and cats), as well as large and very large breeds. (I am not an affiliate of theirs, nor do I receive any compensation for recommending their products.)

Milk Thistle

Milk thistle
 contains silibinin, a compound that has shown to prevent impairment of both short-term memory and recognition memory in mice injected with a highly toxic peptide fragment called Aβ25–35, which exerts neurotoxic properties. Aβ25–35 induces cognitive dysfunction, causing learning and memory impairment; it is also detected in the brains of patients with Alzheimer’s disease. Silibinin works as an antioxidant, protecting the hippocampus (the part of the brain associated with memory) against oxidative damage caused by this powerful neurotoxin.^[22]

Another study on mice showed that supplementation of silymarin for six months markedly protected against Aβ-induced neurotoxicity and improved behavioral abnormalities, including decreasing anxiety. The researchers went so far as to conclude that silymarin shows promise for actually preventing Alzheimer’s disease.^[23]

Phosphatidylserine

Phosphatidylserine is a phospholipid, a class of lipids (fats) found in cell membranes. Several clinical trials have shown that dogs who take dietary supplements containing phosphatidylserine show improvements in signs associated with age-related cognitive dysfunction. On product, Senlife, was shown to improve working memory n dogs after just 60 days of treatment.^[16]

SAMe

In several human studies, reduced SAMe concentrations were detected in the brains of patients with Alzheimer’s disease.^[24]

Supplementation with SAMe has also been shown to effectively reduce the symptoms of depression in people—and might even be as beneficial as some prescription antidepressants.^[25] This is an important finding, since depression often accompanies cognitive decline.

Gluten impairs brain health

In people, gluten sensitivity has been linked with impaired brain function, including learning disabilities, ADHD and memory problems. Gluten sensitivity may even manifest exclusively as a neurological disease, without any GI symptoms.^[26] According to David Perlmutter, MD, FACN, ABIHM, a board certified neurologist and fellow of the American College of Nutrition and author of Grain Brain: The Surprising Truth about Wheat, Carbs, and Sugar—Your Brain’s Silent Killers, gliadin, a protein in gluten, triggers an antibody response in the body that results in elevated levels of inflammatory cytokines. These cytokines are present in patients with Alzheimer’s disease and other neurological conditions, such as Parkinson’s, multiple sclerosis and autism.^[26]

In 2006, researchers from the Mayo Clinic found an association between patients with both Celiac Disease and progressive cognitive impairment, further supporting the link between the damaging effects of gluten and impaired brain health.^[27]

The last thing your aging dog needs is a cascade of brain-related inflammation, so removing gluten from his diet makes perfect sense.

Summary

Cognitive decline is a fact associated with aging in both humans and animals. However, there are simple and powerful nutritional steps that you can take to help prevent, manage and possibly even reverse the most devastating effects so that your best friend can enjoy optimum physical and cognitive health throughout life!

References

Parts of this article were adapted from the book Canine Nutrigenomics: The New Science of Feeding Your Dog for Optimum Health by W. Jean Dodds, DVM and Diana R. Laverdure, MS (Dogwise Publishing, 2015).

1. ^[1] Laflamme DP.(2012). Nutritional Care for Aging Cats and Dogs.Veterinary Clinics of North America:Small Animal Practice, vol. 42, pp.769 –791. ↩
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3. ^[3] Hand MS, Thatcher CD, Remillard RL, Roudebush P & Novotny BJ.(2010). Small Animal Clinical Nutrition (5th ed.). Mark Morris Institute. Topkea, KA. ↩
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    This is great news for the brain. ↩
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19. ^[19] Mercola J. (2012). A Daily 900 mg Dose of this Fat Helped Reverse Memory Loss, Retrieved from http://articles.mercola.com/sites/articles/archive/2012/02/06/without- krill-oil-your-brain-could-degenerate.aspx. ↩
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22. ^[22] Lu P, Mamiya T, Lu LL, Mouri A, Zou LB, Nagai T,…Nabeshima T. (2009). Silibinin prevents amyloid β peptide-induced memory impairment and oxidative stress in mice. British Journal of Pharmacology, 157(7), 1270-1277. ↩
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25. ^[25] WebMD. (2013). SAMe, Retrieved from http://www.webmd.com/vitamins-supplements/ingredientmono-786-SAMe.aspx?activeIngredientId=786&activeIngredientN ame=SAMe. ↩
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