Cognitive Dysfunction in Cats
According to the latest American Veterinary Medical Association census figures, about 82 million cats currently reside in U.S. homes, up from 71 million in 2001. Much of this impressive increase, no doubt, stems from the pleasure that a growing number of people derive from having a cat around the house. But the dramatic population increase may also be attributed to the fact that cats in general are living longer nowadays than they typically did in the past. As a result of improved home care, better nutrition, advances in veterinary medicine, and so forth, it is not uncommon for a cat to live to the ripe old age of 20 or 21 years—the equivalent of age 96 to 100 in a human.
There’s a downside to this good news, however. As cats grow older, they, like humans, become increasingly susceptible to the onset of disorders associated with aging. As the years go by, their organs gradually function less efficiently, for example, and the potency of their immune systems naturally declines. Among the most troubling, and in some respects most baffling, of age-related feline disorders is cognitive dysfunction, a puzzling, progressively debilitating condition whose signs resemble those associated in humans with Alzheimer’s disease and senile dementia.
The behavioral signs of cognitive dysfunction tend to become clearly noticeable in cats that are 10 years of age or older. The signs include spatial disorientation; wandering away from home into unfamiliar territory; lack of interest in playing; excessive sleeping; altered cycles of sleep and wakefulness; long periods of staring blankly into space or at walls; indifference to food and water; urinating and defecating outside the litter box; and seemingly unprompted episodes of loud vocalizing, frequently in the middle of the night.
Some of the bizarre behavior may be attributable to the gradual impact of a long-standing physical condition that worsens as a cat grows old or to diseases commonly found in older cats. The pain of arthritis, for example, can intensify over the years and cause a formerly athletic cat to slow down dramatically as the years pass. Kidney failure may impact litter box behavior by causing excessive urination and soiling of the litter box, causing some fastidious cats to find alternative places to eliminate. Arthritis may also hinder a cat’s ability to get into the litter box in time. Night-time vocalizing is relatively common in hyperthyroid cats or cats with hypertension, and hypertension can also cause retinal detachment and blindness, leading to anxiety and confusion. Progressively painful periodontal disease can discourage the cat from visiting its food bowl with the same enthusiasm it showed at a younger age.
The signs of cognitive dysfunction may also be traced to a neurologic disorder, according to Alexander de Lahunta, DVM, emeritus professor of anatomy at Cornell University’s College of Veterinary Medicine. “If I’m examining a cat,” he says, “and it acts as if it’s in a world of its own, doesn’t respond to me, paces in a circle, or gets itself in a corner and just stays there, I’ll consider that to be a prosencephalon problem.” The prosencephalon, he explains, includes the largest portion of the brain, the cerebrum. This area controls a cat’s response to its environment, its vision and hearing, and such vital functions as sleeping and eating.
Anomalous behavior stemming from that part of the brain, explains Dr. de Lahunta, can be caused by a variety of physical problems, such as tissue inflammation, tumors, trauma, or a metabolic disease. If magnetic resonance imaging (MRI) and analysis of cerebrospinal fluid fail to reveal a physical problem in the brain, says Dr. de Lahunta, then the problem is something that is probably best treated by an animal behaviorist or veterinary psychiatrist.
After other potentially causative conditions, such as hyperthyroidism and kidney disease, are ruled out, a veterinarian may prescribe an anti-anxiety drug, such as fluoxetine, to allay some of the alarming signs of cognitive dysfunction. (A drug called L-deprenyl has proved successful in improving brain function in dogs but has not yet been approved for use in cats.)
Animal behaviorists note that cat owners can play a significant role in delaying the progress of feline senility and its accompanying disabilities. Among their suggestions: feed an aging cat a diet rich in vitamin E and antioxidants, substances that are believed to retard the effects of aging; avoid bringing another animal into the household whose presence might be stressful to the cat; and make sure that litter boxes are conveniently accessible, with low sides for easy access. If the elderly cat is having trouble going up and down stairs, provide ramps as needed throughout the house. And be sure to take the cat to a veterinarian for routine checkups so health problems are identified in their early stages, when they are most treatable.
By Tom Ewing