How to Treat Cognitive Dysfunction
BackgroundCognitive dysfunction syndrome (CDS) is a chronic, progressive disease characterized by neuronal loss and neuroaxonal degeneration.1,2 In dogs, CDS has some similarities to human Alzheimer’s disease in neuroanatomic pathology.3 Treatments include environment and behavior modification, comorbidity considerations, and medication for possible anxiety and agitation.
The prevalence of CDS in dogs and cats is fairly high. Reportedly, 28% of dogs 11 to 12 years of age and 68% of dogs 15 to 16 years of age show at least one sign associated with CDS.4 In laboratory settings, dogs begin showing impairment in specific learning and memory tasks as early as 6 to 8 years of age.5 The clinical presentation in cats is more ambiguous, although they may begin to show signs consistent with cognitive dysfunction at approximately 10 to 11 years of age. One study reported that 50% of cats older than 15 years of age had possible CDS<sup.5,6 sup>
Related Article: House Soiling & Cognitive Dysfunction Syndrome
Screening patients 10 years of age or older as part of routine examination can allow for treatment to slow CDS progression or address signs that may distress patient and caregiver. Anxiety (eg, restlessness, fear or phobias, separation anxiety) can be a common sign of CDS. The most common signs in dogs are alterations in social interaction and a break in housetraining.7 Altered social interactions may reflect an increase in neediness (ie, a dog seeks the owner more often) or the opposite (ie, a dog appears more aloof and disinterested in engaging the owner). In cats, the most common signs are vocalization (often at night) and housesoiling without medical cause.8 One of the most troubling signs for caregivers is the potential change in sleep–wake cycles: patients may remain awake throughout the night and pace, whine, or vocalize. Patients may also show anxiety or fear (agitation) that may result from disorientation.
Classically, the signs of CDS in dogs have been described with the acronym DISH-A:
Disorientation (eg, wandering, going to the hinged side of doors, appearing confused)
Social Interaction changes
Sleep–wake cycle changes
Housetraining breaks (when previously housetrained)
Activity level changes (decreased or increased)
DiagnosisIn patients with positive CDS responses on screening, a more detailed behavioral history can provide key information regarding areas of concern (see How I Diagnose CDS). It is important to include specific questions about when problem behaviors are most frequently observed, whether there are identifiable triggers for behaviors, and whether signs of anxiety are present.
Related Article: Cognitive Function in Older Dogs
A clear and consistent rating scale for each of the signs can help caregivers and veterinary personnel track changes over time. Having caregivers videotape behaviors can also provide insight on severity. The patient may be afflicted with several disease processes that can complicate CDS diagnosis and/or treatment. Chemistry panels, hematology profiles, and urinalyses can help determine whether other medical conditions exist. Imaging or advanced diagnostics may be needed to rule out other neurologic or painful conditions (see Potential Medical Causes of Behavioral Changes).
How I Treat Cognitive Dysfunction
Treat and manage comorbid medical conditions.
Provide environment and behavior modification.
Inform caregivers that treatment and management options are designed to slow CDS progression, butcomplete resolution may not be possible.
CDS is chronic and progressive, and the goal is to maintain function and quality of life for both patient and caregiver for as long as possible
Provide opportunities for engagement throughout the day to help maintain a normal sleep–wake cycle.
Opening the blinds or windows can help keep patients awake during the day.
Provide physical and mental stimulation.
Enrichment (eg, training, play, exercise, toys) can help boost and maintain cognitive function.
Puzzle and food toys are forms of enrichment.
Structured and consistent playtime and exercise reinforce routines and are important for lowering stress and promoting cognitive health.
Provide modified and alternative toileting opportunities for older patient
This may include multiple, low-sided litter boxes for cats and provisions for dogs to go out often or have designated elimination areas in the home.
Avoid marked changes in schedules, environments, and routines if possible.
Train settle techniques for dogs using a dedicated mat.
Training when dogs are not agitated can condition a calm response that can be useful when dogs become more anxious or restless.
Provide nutritional support.
Supplemented canine diets can provide fatty acids, additional antioxidants to combat the reactive oxygen species that increase with age, and alpha-lipoic acid to support mitochondrial function.9
A diet enriched with medium-chain triglycerides has been shown to improve cognitive function in geriatric dogs.<sup10 sup>
Other nutritional supplements may be added to regular diets: l-theanine (for anxiety), S-adenosyl-L-methionine (SAMe),11 phosphatidylserine,12 and antioxidants.
SAMe, an endogenous methyl donor used to decrease oxidative stress by stimulating brain glutathione, has been shown deficient in humans with Alzheimer’sdisease.
Phosphatidylserine, a phospholipid component of the cell membrane, has several effects on acetylcholine and acetylcholinesterase, though data on its use in humans is mixed.
Formulations for phosphatidylserine and antioxidant mixtures exist.
Provide pharmacologic support.
Selegiline hydrochloride (Anipryl, online.zoetis.com/us), a monoamine oxidase inhibitor (MAOI), is currently approved in the United States for CDS treatment in dogs.
It has not been approved for use in cats but has been used off-label.
In the author’s experience, if improvement or stabilization is seen within the first month, improvement may continue in the following month or may plateau.
If no improvement is seen, the patient may benefit from another medication that addresses clinical signs.
MAOIs cannot be combined with other serotonergic drugs or other MAOI-containing products, including some antiparasitic products that include amitraz.
Fluoxetine or sertraline
Both are selective serotonin reuptake inhibitors (SSRIs) that can help treat anxiety in geriatric patients.
Neither can be used with an MAOI.
Sleep aids (eg, melatonin, benzodiazepines, trazodone)
Targeted therapy at bedtime can help reset the sleep–wake cycle, providing patients and caregivers with rest.
MARGARET E. GRUEN, DVM, MVPH, DACVB, is a veterinary behaviorist at North Carolina State University. Her interests include gerontology, feline pain behavior, and canine and feline behavior. She has written and been published on medically treating canine anxiety disorders and developing outcome measures for degenerative joint disease-associated pain assessment in cats. She frequently contributes to the Veterinary Behavior Symposium held in conjunction with the AVMA convention. Dr. Gruen earned her DVM from University of Illinois and her MVPH from NCSU.
COGNITIVE DYSFUNCTION • Margaret E. Gruen
1. Neurobiology of the aging dog. Head E. Age (Dordr) 33:485-496, 2011.2. Beta-amyloid accumulation correlates with cognitive dysfunction in the aged canine. Cummings BJ, Head E, Afagh AJ, et al. Neurobiol Learn Mem 66:11-23, 1996.3. Dogs with cognitive dysfunction syndrome: A natural model of Alzheimer’s disease. Bosch MN, Pugliese M, Gimeno-Bayón J, et al. Curr Alzheimer Res 9:298-314, 2012.4. Prevalence of behavioral changes associated with age-related cognitive impairment in dogs. Neilson JC, Hart BL, Cliff KD, Ruehl WW. JAVMA 218:1787-1791, 2001.5. Beta-amyloid deposition and tau phosphorylation in clinically characterized aged cats. Head E, Moffat K, Das P, et al. Neurobiol Aging 26:749-763, 2005.6. Visuospatial function in the beagle dog: An early marker of cognitive decline in a model of human aging and dementia. Studzinski CM, Christie LA, Araujo JA, et al. Neurobiol Learn Mem 86:197-204, 2006.
Prevalence and risk factors of behavioral changes associated with age-related cognitive impairment in geriatric dogs. Azkona G, García- Belenguer S, Chacón G, et al. J Small Anim Prac_t 50:87- 91, 2009.8. Clinical signs and management of anxiety, sleeplessness, and cognitive dysfunction in the senior pet. Landsberg GM, Deporter T, Araujo JA. _Vet Clin North Am Small Anim Pract 41:565-590, 2011.9. Assessment of nutritional interventions for modification of age-associated cognitive decline using a canine model of human aging. Araujo JA, Studzinski CM, Head E, et al. Age(Dordr) 27:27-37, 2005.10. Dietary supplementation with medium-chain TAG has long-lasting cognition-enhancing effects in aged dogs. Pan Y, Larson B, Araujo JA, et al. Br J Nutr 103:1746-1754, 2010.11. NOVIFIT (NoviSAMe) tablets improve executive function in aged dogs and cats: Implications for treatment of cognitive dysfunction syndrome. Araujo JA, Faubert ML, Brooks ML, et al. Int J Appl Res Vet Med 10:90-98, 2012.
Improvement of short-term memory performance in aged beagles by a nutraceutical supplement containing phosphatidylserine, Ginko biloba, vitamin E, and pyridoxine. Araujo JA, Landsberg GM, Milgram NW, Miolo A. Can Vet J 49:379-385, 2008.
Cognitive dysfunction in cats: A syndrome we used to dismiss as ‘old age’. Landsberg GM, Denenberg S, Araujo JA. J Feline Med Surg 12:837-848, 2010.