There is no formal criterion for the establishment of cognitive dysfunction syndrome (CDS) in cats with changes in behavior and/or brain aging. Clinical signs in cats mimic those in dogs and are based upon the canine wellness checklist called “DISHA,” which includes the parameters of disorientation, interactions with owners and other pets, sleep-wake cycles, house soiling, and activity levels. Clinical signs may also include excessive vocalization, altered responses to stimuli (less responsive or anxiety/ irritability), decreased self-hygiene, and/or alterations in appetite. The older the cat, the more likely the behavioral change; accordingly, 50% of cats over 15 years of age and 28% of cats aged 11 to 14 years are affected.

Changes in the brain, including cerebral atrophy, have been documented in cats. Other researchers have identified multifocal areas of decreased signal intensity on T1-weighted scans, predominantly in the pyriform lobe, and this may be associated with cognitive decline. Neuronal loss may be identified in the cerebella of aged cats, resulting in decreases in Purkinje cell dendrites. This could lead to declines in information processing and motor deficits.

Drug therapy for cats is currently extrapolated from canine studies and clinical results. Medications with potential applications to cats include selegiline, propentofylline, and antioxidant therapy. Anticholinergics should be avoided due to cholinergic decline in senior pets and unpredictable therapeutic results. Additional medications under consideration for behavioral changes and anxiety disorders associated with CDS include sertraline and some benzodiazepines with limited intermediate metabolites (lorazepam, oxazepam and clonazepam). In addition, natural therapies may include melatonin, aromatherapy, l-theanine, alpha-casozepine, and pheromones.

Commentary
There is currently an improved and evolved understanding of age-related changes in cats. Organic changes in cats’ brains do exist and have effects on feline behavior. A thorough workup of the patient is still necessary to exclude medical reasons for behavioral changes, including pain/discomfort, arthritis, hepatic disease, endocrine disorders, neurologic diseases, infectious diseases that affect the immune or neurologic systems, tumors or inflammatory diseases, hypertension, and environmental stresses. Physical, funduscopic, and neurologic examinations; complete blood count; serum biochemical profile;thyroid hormone level; urinalysis; and blood pressure measurement are considered vital parts of a proper medical evaluation for any cat that presents with a geriatric-onset behavioral change.—Heather Troyer, DVM, Diplomate ABVP (Canine & Feline Practice)

Cognitive dysfunction in cats: A syndrome we used to dismiss as ‘old age.’ Landsberg GM, Denenberg S, Araujo JA. J FEL MED SURG 12:837-848, 2010.