Can a dog serve as a substitute for a person’s failing memory? Rather amazingly, the answer is yes.

People in developed countries are living considerably longer, which is certainly great, though not without its challenges–one of the major problems for the elderly and their caretakers is the decline of memory-related mental abilities. In the United States, it is estimated that around 15 percent of people 65 and older will suffer from some form of dementia, while an additional 10 percent will suffer from Alzheimer’s disease. This amounts to around 5.5 million people in the US alone, which presents a looming challenge for both the health care system and families.

Luckily, dogs are poised to help. Let me explain.

Not all forms of memory are affected equally in people suffering from dementia or Alzheimer’s disease. Psychologists often start by dividing memory into to large groupings that they call “explicit” or “implicit” memory. The easiest way to distinguish these is to note that explicit memories are the ones that you can describe or call into your mind at will, while implicit memories are automatic and not really conscious. Learned skills are good examples of implicit memories. Thus, although you might remember how to ride a bicycle (since you can easily do it) trying to describe to someone else what you have to do to stay upright on a bicycle is virtually impossible. You know what to do, but you can’t make these actions conscious in such a way as to communicate them to others. These implicit memories are very strong and often survive the effects of memory loss due to age.

Explicit memories are the ones which are easily brought into consciousness and which we can describe verbally. When we consider explicit memory it comes in two varieties, namely “episodic” and “semantic” memory. Episodic memory is memory for what you have personally experienced. When you answer a question about what you had for dinner last night or which clothes you wore yesterday, you are recalling episodic memories. This is different from semantic memory which involves memory for facts. To answer a question such as “Who was George Washington?” or “What is the climate like on the moon?” will involve semantic memory. It is not episodic memory since you never met George Washington, nor have you visited the moon. Some people say that episodic memory is a sort of mental time travel in which you revisit events that you experienced by bringing them into consciousness. Episodic memory is not based upon practice or repetition, since most life events occur only once and nonetheless are remembered. Episodic memory is the most fragile form of memory and it is the most likely to be damaged by dementia. Luckily, it’s possible to have a dog substitute its own episodic memory to assist people with memory problems.

One of the first people to use a memory assistance dog was John Dignard, a man who, when I interviewed him in 2003, was living in Wetaskiwin, a town in Alberta, Canada. Dignard was hit by a car at the age of five and the accident caused brain damage. He was left with learning difficulties and a very unreliable short-term memory. That means that before anything makes it into his long-term memory, it must be repeated and relearned many times. Early memories are still there, so that Dignard can remember his phone number from when he was four, but new ones are a problem. For instance, it took him a year after his marriage to remember his wife’s name. He told me, “When you ask someone’s name 600 times because you can’t remember, it’s very frustrating.” At a very pragmatic level, Dignard’s lack of short-term episodic memory made simple tasks nightmares. If Dignard went to a shopping mall, by the time he came out he usually had completely forgotten where his car was parked. It is in such situations that the episodic memory ability of a dog becomes important. Dignard can now go shopping with confidence because of a German Shepherd Dog named Goliath, who serves as his memory aide. Goliath is the third such memory assistance dog Dignard has had. Obviously Goliath can’t help with names, phone numbers or shopping lists, but the dog does serve the same purpose as the ball of string that Theseus let out as wended his way through the labyrinth in order to find his way back out after he slew the Minotaur. Goliath’s task is to lead his master back to the places that he can’t remember, such as the way out of a building he has only visited one time. In other words, the dog must use his episodic memory to remember where an exit is or where his owner’s car was parked.

Dignard told me “I’d be lost all the time without him. Now I just tell him ‘go to the exit door,’ or I tell him ‘back to the car,’ and he takes me there.” Goliath’s episodic memory substitutes for the episodic memories that his master has such difficulty retrieving.

Fortunately, most forms of age-related dementia do not have a sudden onset, and in the beginning and middle stages of the diseases people can still have a useful, functional, and somewhat independent life if they have adequate assistance and support services. However, even in the early stages, there are intermittent problems associated with memory loss and a dimming of mental abilities. For example, dementia sufferers can forget to take their medication or even to eat. It is easy for them to get lost and not be able to find their way home and as a result they often experience feelings of frustration, isolation, anger, and a sense of helplessness. Ultimately, they can find themselves to be effectively prisoners in their own homes and are completely dependent on the assistance of other people to allow them to go outside. For such people, a memory assistance dog could make all the difference.

In the past few years two groups of individuals have started to train dogs to assist people with Alzheimer’s and dementia. The first is in Israel and was the brainchild of Dafna Golan-Shemesh, a social worker with expertise in caring for Alzheimer’s patients, and her partner, Yariv Ben-Yosef, a professional dog trainer. More recently, a similar project was initiated by students at Scotland’s Glasgow School of Art’s Product Design Department and then further developed by a partnership between Alzheimer Scotland, Dogs for the Disabled, and Guide Dogs Scotland.

These memory assistance dogs do not work on a harness the way guide dogs for the blind do but rather on a six-foot leash so that they can be out in front of the person and actually lead in an appropriate direction. The main task of the dementia service dog is to bring his charge home when the order “Home” is given. If the patient forgets to give the order to return home or is lost to the degree that he wanders far from the house and into an unfamiliar area, worried caretakers or family can activate an electronic GPS navigation device that is installed on the dog’s collar. This not only helps locate the missing pair but also emits a recognizable tone, which the dog interprets as an alternate command instructing him to lead his patient home. If, for some reason, the patient is not capable of accompanying the dog home, the dog is trained to remain with him and to call attention to the situation by barking. In worst-case scenarios where the patient wanders out of the house without his canine assistant, the dog is trained to track him by his scent.

Dogs love predictability and routine and this is the hook upon which much of the training of the dementia assistance dogs is based. For example, Alzheimer’s disease can make people confuse day and night or forget basic things such as washing or drinking enough water. The dogs are trained to help guide people through the day, encouraging them to open a cupboard that contains food for the dog and also a prominent note to the owner reminding him that he has to eat as well. In the same way that dogs respond to the sound their collar emits meaning “Go home,” they are trained to respond to other sound-triggers in the home. For example, an electronic timer can sound a tone that causes the dog to bring a bite-proof bag of medicine with a note inside reminding the patient to take it, while another tone prompts the dog to walk his owner to the bathroom where he will find a note indicating that he should wash himself and take a glass of water. The dogs are also trained to trigger an alarm in the house should the patient fall and not get up within a reasonable amount of time or if they hear a choking sound.

Almost as important as the direct services provided by these assistance dogs is the fact that these animals also provide companionship and friendship for their owner. They create a psychological anchor to reality by maintaining a meaningful daily routine that adds to the quality of life. The very fact that the dogs must be walked every day promotes exercise for the patient and encourages social interaction between the dementia sufferer and other people. Research has shown that an individual who walks with a dog is more likely to be engaged in conversation by other people along the way. A significant aspect is that such interactions are very predictable, with questions like “What is your dog’s name?” and “How old is he?” These positive and predictable social interactions reduce the sense of loneliness and isolation experienced by people with dementia. The very fact that they are out and about with their dog also provides a sense of independence to the patient and reduces the feelings of helplessness and dependency which can lead to some of the severe forms of depression which are often encountered in Alzheimer’s and dementia sufferers.

Now if I could just find a dog that would help me remember the names of the people that I meet…