Cognitive Dysfunction Syndrome

BY KERRI WIEDMEYER, DVM, WVRC

What it is:
Cognitive Dysfunction Syndrome (CDS) is degeneration of brain activity that occurs with age. Commonly, these changes occur slowly with time, typically in dogs and cats over the age of 11 years old, with prevalence increasing the older the pet becomes. CDS is commonly compared to dementia in humans as many clinical signs can be similar and also worsen with age.

Causes:
Brain atrophy, or degeneration, occurs with age. This means the actual size of the brain decreases as well as the number of neurons. These changes are more notable in the cerebellar and cerebral areas of the brain. As atrophy occurs, cerebrospinal fluid fills in the empty areas.

Levels of neurotransmitters such as dopamine have been found to decrease with age. This results in decreased neurologic signaling and activity.

Beta amyloid plaques, which are proteins that damage neurons, increase with age, causing further cognitive dysfunction.

Vascular changes are common with age, and micro-bleeds and infarcts can occur that stop the normal blood flow to the brain and thus decrease oxygen and glucose to the brain.

Signs:
1. Confusion. Examples include staring off, getting stuck in a certain location in the house such as a corner or closet.
2. Loss of memory, changes in ability to learn. This includes accidents in the house or problems with training or known commands.
3. Activity changes like excessive licking, pacing and repetitive behavior.
4. Changes in response to stimuli/interactions with people. For instance, excessive barking, lack of interest and separation anxiety.
5. Change to sleep cycle. This may include pacing at night, deep sleep during the day, anxiety and restlessness.

Diagnosis: Diagnosis of CDS is made based on clinical signs, the pet’s history and how they respond to treatment. Other disease processes that can cause similar signs should be ruled out or treated prior to diagnosis of CDS.

Treatments: Diets containing omega-3 fatty acids, antioxidants and mitochondrial cofactors have been shown to improve cognitive function related to age. These diets may take several weeks before improvement is noted.

Medications: Selegiline is an enzyme blocker that slows down the breakdown of catecholamines such as dopamine, norepinephrine and epinephrine. It can also increase the production of dopamine. Most of the time, improvement is noted in 2-4 weeks after the medication has been started.

S-adenosylmethionine (SAM-e) is a supplement more commonly used for liver support. It has been shown, however, to have benefits in treating cognitive dysfunction.

Anti-anxiety calming medications and medications that increase cerebral blood flow have also been shown to help with the clinical signs associated with cognitive dysfunction.

Environmental Therapy: Environmental enrichment is a very important part of improving and maintaining cognition. Teaching new tricks can benefit both the owner and the pet and establish routines. New toys and consistent exercise are recommended as well. If hearing loss is a part of the aging process, then working on hand signals can be very beneficial and make for an easier transition if deafness occurs.

Prognosis: At the end of the day, age should not be thought of as a disease. Many of these dogs can have a good quality of life with the proper care from their loving owners.