Cognitive dysfunction is an age-related neurodegenerative disease that impairs memory and learning.
Clinical signs and immuno-histopathological findings of CDS resemble forms of dementia seen in Alzheimer patients (Dementia Alzheimers Type (DAT)).
CDS can manifest itself in multiple unspecific clinical signs that increase in quantity and severity over time in affected cats.
Presenting signs
Summary: changes in cell function and neurotransmission in the brain of the CDS patients lead to malfunctions of short term memory, loss of learned behavior, impairment of the processing of sensory information, reduction in cognitive capacity, and alterations of mood. Taken together these create typical patterns of signs that owners recognize.
Progression: the progress of CDS is related to the general rate of aging in the feline. Quite significant changes can occur in the space of weeks or months. Worsening of the condition may be precipitated by stressful events such as hospitalization, kenneling, surgery or a house move. Ideally, cats should be behaviorally assessed before these events.
Emotional changes: mild emotional changes may be the first signs of the onset of dementia. Signs include depression (reduction in activity, play and interest in activities the cat formerly enjoyed). A depressed mood is also a common sign of chronic pain and ill health. Increases in anxiety and fear leading to irritability and aggressiveness.
Defects of short-term memory: the cat repeatedly performs certain actions such as asking for attention, food and other rewards. These behaviors may also be learned as a result of owner reinforcement. Malfunction of short-term memory is at the root of many of the problems seen in CDS.
Disorientation: the cat has trouble recognizing people, locations, or objects. This may lead to secondary problems, such as house soiling and trouble to find locations in the home, eg door to outside, cat flap, water and food dish.
Changes in sleep-wake cycle: the cat tends to sleep mostly during the day and appears restless at night, often waking up and crying out loudly. Pain and illness are also significant factors in night time restlessness in cats, eg chronic arthritic pain may make rest uncomfortable, and deafness can result in the cry becoming loader than previously.
Loss of learned behaviors: failure to respond to commands and social signals that inhibit unwanted behavior. This contributes to loss of social inhibition and alterations in relationships with people and other animals in the home.
Loss of house training (example of a learned behavior): a previously house trained cat will suddenly urinate and/or defecate inside the house and/or outside its littler box. This clinical sign can be caused by numerous medical and behavioral problems that have to be ruled out, especially osteoarthritis, hyperthyroidism and hypertension. Once the underlying cause of CDS has been treated the cat may need to be re-housetrained from scratch.
Changes in interaction with the environment: reduced greeting of the owner, familiar persons or pets, decreased response to commands. A depressed mood and lack of interaction tends to isolate cats from their owners, who may not instigate play or give attention. Through a loss of stimulation and reward of normal activity the degradation of the human-animal bond leads to social isolation that contributes to worsening signs of CDS.
Neurological : in the latter stages of CDS, neurological impairment may be seen. These include ataxia, apparent sensory loss (loss of vision/hearing) and changes in locomotor reflexes. Cats can occasionally progress to this stage quite rapidly (within a few weeks). Any neurological signs must be investigated thoroughly as there are numerous other potential medical causes.
Age predisposition
The onset of clinical signs is seen in older cats, with as many as 28% of pet cats aged 11–14 years developing at least one geriatric-onset behavior problem.
This increases to over 50% for cats of 15 years of age or older.
Sex predisposition
CDS occurs equally in neutered male and female cats.
Increased monoamine oxidase B concentration and decreased dopamine concentration.
Anemia.
Hypertension (due to eg kidney disease, hyperthyroidism, diabetes, etc).
Epidemiology (population dynamics)
More than one quarter of the felines seen in veterinary practices belong to the population of cats that are at risk to develop CDS (7 years of age or older).
Approximately 50% of 15 year old cats show signs of CDS.
Spatial disorientation or confusion, eg getting trapped in corners or forgetting the location of the litter box (house-soiling is the most common reason for referral of old cats to behaviorists).
Altered social relationships, either with their owners or other pets in the household ,eg increased attention seeking or aggression .
Altered behavioral responses, eg increased irritability or anxiety, or decreased response to stimuli.
Changes in sleep/wake patterns.
Inappropriate vocalization, eg loud crying at night.
Altered learning and memory, such as forgetting commands or breaking housetraining.
Changes in activity, eg aimless wandering or pacing, or reduced activity.
Altered interest in food, either increased or, more typically, decreased.
Decreased grooming.
Temporal disorientation, eg forgetting that they have just been fed.
Diagnostic investigation
Full history, including the possibility of previous trauma (which may have lead to arthritis), any potential exposure to toxins or drugs, and any recent environmental changes (in the household, family members, diet, etc.). Asking specific questions about alterations in the cat's behavior can help in determining how the cat has changed (see Mobility / Cognitive Dysfunction Questionnaire).
Full physical examination (including assessment of body weight, body condition score, retinal examination and a full neurological and orthopedic examination).
Assess systemic blood pressure (this is particularly important as hypertension occurs commonly in older cats and cat many of the same signs as CDS).
Assess hematology and serum biochemistry, including thyroid hormone level .
Urine analysis (including urine protein to creatinine ratio and bacterial culture ).
Further investigation may include:
Where appropriate, serological testing for FeLV, FIV, toxoplasmosis or FIP.
Thoracic, abdominal or skeletal radiography, abdominal ultrasound examination, ECG, echocardiography, intestinal endoscopy / exploratory laparotomy and biopsy collection, as indicated from initial findings.
Head CT or MRI.
Confirmation of diagnosis Discriminatory Diagnostic features
Neurological defects (either sensory or motor deficits).
Hypertension (may either be primary or secondary to hyperthyroidism, renal failure, diabetes mellitus, acromegaly or hyperadrenocorticism), anemia, congestive heart failure, hypoxia.
Endocrine system
Common signs:
Aggression, anorexia, anxiety, changes in sleep-wake cycle, decreased or increased activity and reactivity, polyuria and polydipsia, polyphagia.
Rule outs:
Hyperthyroidism , diabetes , Cushings disease .
Gastrointestinal tract
Common signs:
Changes in activity level, house soiling, neurological signs, weight changes.
Aggression, exercise intolerance, house soiling, pain, weakness.
Rule outs:
Osteoarthritic changes , decreased bone and muscle mass, fat-muscle ratio, neuro-muscular function, pain. The importance of arthritis should not be overlooked. Radiographic evidence of degenerative joint disease is present in 70-90% of cats over 10 years of age. Associated pain and/or dysfunction can result in reduced activity and mobility, aggression, altered interactions with the family, and/or loss of litter box training. Owners can help their arthritic cats by adjusting their house; for example, by moving food and water bowls to lower surfaces, adding ramps to allow easier access to favoured sleeping areas, providing deep comfortable bedding that will support and protect the cat's joints (heated beds can be particularly soothing), and placing low-sided litter boxes within easy cat reach.
Aggression, anorexia, anxiety, changes in sleep-wake cycle, changed reactivity.
Rule outs:
Decreased sensory function (visual ability, hearing, olfaction, smell, tactile function).
Urinary tract
Common signs:
Polyuria and polydipsia, house soiling, incontinence.
Rule outs:
All causes of feline lower urinary tract disease , especially urinary tract infections and bladder neoplasia (in this age group); urethral incompetence; causes of polyuria and polydipsia, especially renal disease, hyperthyroidism and diabetes; house soiling, submissive urination, separation anxiety, urine marking.
Avoid changes in the house that may lead to disorientation.
Keep a strict routine to make the environment more predictable.
Increase the number of environmental cues that enable the cat to navigate its environment (audible, odor, tactile), eg use specific cues to identify particular rooms and passages: a continuously playing radio in one room, textured rugs and fragrances in others.
Ensure that all 5 key resources are available and easily located by the cat:
Food.
Water.
Litter box.
Resting places (create a secure bed area that is comfortable).
Places to hide.
Avoid slippery surfaces, obstacles and stairs. Use special matting under rugs to make them more stable under foot.
Encourage the cat to interact.
Continue the reward based training.
Nutrition:
Senior diets. Prescription diets that supplement antioxidants, eg j/D, Hills ® or equivalent antioxidant supplements (care that lipoic acid is not included as it is toxic in cats) .
Pharmacological treatment
As yet, there are no published studies using any food supplements or drugs in cats with CDS. There are no licenced products to treat CDS in this species. However, treatment has been extrapolated from dog studies and the treatments and doses shown below have been used in cats. The American Association of Feline Practitioners supports the use of selegiline in these cats.
Selegiline 0.25-1 mg/kg SID PO. Dopaminergic (monoamine oxidase B inhibitor). Increases exploratory behavior, enhances reinforcement of behavior, improves cognition, reduces apprehension, neuroprotective (reduces apopotosis and induces encatenous antioxidant enzymes). Do not combine with selective serotonin reuptake inhibitor or tricyclic antidepressant.
Propentofylline 12.5 mg/cat SID PO. Increases cerebrovascular blood flow, experimentally this drug is neuroprotective and reduces neurotoxicity of beta-amyloid.
Feline Facial Pheromone (Feliway, CEVA): synthetic analogue is available in an electrically operated diffuser. Reduces anxiety and increases acceptance of environmental stimuli. Potential use in early phase of treatment to reduce anxiety, whilst waiting for effects of diet and medication. It may be useful to install a Feliway diffuser when changes in the environment are anticipated, eg in the new home in preparation for a house move.
Treat all medical problems:
Geriatric animals frequently suffer from multiple problems all of which contribute to the impairment. Successful treatment of CDS demands proper management of all medical problems.
Geriatric animals often benefit more from medical intervention than younger ones and their quality of life is more easily improved.
Review current treatment of existing problems. There is often reluctance to change treatment in older cats, but their treatment must be re-evaluated regularly.
Review pain management .
Monitoring
Many cats improve significantly on treatment and can (temporarily) return to a relatively normal level of functioning. The condition is still progressive.
In responsive individuals dietary modification produces some improvement within 4-6 weeks.
Psychoactive drugs such as selegiline often produce effects by week 6-8.
It is sometimes hard to appreciate the changes in the cat's behavior because initially these will be subtle. Encourage the owner to keep a daily log of the cat's behavior.
Monitor the cat's progress weekly during the first 2 months. Owners will need support throughout the initiation and maintenance phases of treatment.
Subsequent management
Treatment
Schedule semi-annual geriatric health and medical checks.
Create a program of environmental enrichment to encourage activity in line with the cat's improving cognitive functioning. Mental stimulation is essential to improve prognosis.
Ask owners to make a list of the (gentle) games and activities the cat used to enjoy before CDS. Encourage them to actively offer the cat opportunities to do these things so that it may return to its previous pattern of behavior.
Plan a program of reward based training (punishment is absolutely to be avoided) to retrain house-cleanliness and other lost learned behaviors.
Annual medical check-up and geriatric care, starting at 7-10 years of age, depending on the individual's nature, breed and presentation.
Educate owners to notice and mention early signs of CDS (emotional changes, loss of interaction, etc).
Offer a balanced diet, depending on the cat's nutritional needs.
Body weight does not influence the prevalence of CDS signs. But food restricted dogs have a delayed onset of chronic diseases and a significant longer life span, and the same is also likely to be true for cats. Cognitively impaired cats of normal bodyweight may be easier to manage than obese ones.
Adequate (age, size) physical exercise and mental stimulation.
Symptoms are typically irreversible and progressive, but this decline can be slowed and some mental function can be temporarily rehabilitated by effective treatment and management.
Early intervention offers the best chance of delaying progression.
The use of neuroprotective diets and drugs combined with a stimulating environment can effectively delay progression so that CDS need not be a lifespan limiting illness.
Veterinary geriatric care, pharmacological intervention, environmental management, and dietary management can help to slower the process and improve quality of life.
Reasons for treatment failure
Owner non-compliance with treatment and management.
Assumption that the behavioral changes are inevitably associated with aging.
Normal progression of the aging process and associated signs.
Landsberg G (2006) Therapeutic options for cognitive decline in senior pets. JAAHA42 , 407-413.
Gunn-Moore D A, McVee J, Bradshaw J M, Pearson G R, Head E & Gunn-Moore F J (2006) Beta-Amyloid and hyper-phosphorylated tau deposition in cat brains.J Feline Med Surg8, 234-242 PubMed.
Gunn-Moore D A, Moffat K, Christie L-A, Head E (2007) Cognitive dysfunction and the neurobiology of aging in cats. JSAP48, 546-553
Head E (2001) Brain aging in dogs: Parallels with human brain aging and Alzheimer's disease.Veterinary Therapeutics2(3),247-260.
Head E M K, Das P, Sarsoza F, Poon W W, Landsberg G, Cotman C W, Murphy M P (2005) Beta-Amyloid Deposition and Tau Phosphorylation in Clinically Characterized Aged Cats. Neurobiol Aging26, 749-763.
Head E & Zicker S C (2004) Nutraceuticals, aging and cognitive dysfunction. Vet Clin North Am Small Anim Pract 34, 217-228 PubMed.
Moffat K S & Landsberg G M (2003) An investigation of the prevalence of clinical signs of cognitive dysfunction syndrome (CDS) in cats. JAAHA39, 512 (abstract).
Other sources of information
Heath S (2002) Behaviour problems of the geriatric pet. In: Horwitz, Mills D, Heath S (eds) BSAVA Manual of Feline and Feline Behavioural Medicine. British Small Animal Veterinary Association.
Vetstream contributor(s)
Dr Danielle Gunn-Moore BSc BVM&S PhD MACVSc MRCVS
Mr Jon Bowen BVetMed MRCVS Dip(AS)CABC
Dr Petra A Mertens DrMedVet FTAV DiplECVBM-CA DiplACVB
A depressed mood is also a common sign of chronic pain and ill health.
Do not combine with selective serotonin reuptake inhibitor or tricyclic antidepressant.
