Medical ethics can be thorny even with relatively benign topics. But physician-assisted suicide to achieve “death with dignity’ is especially fraught. It raises issues of personal beliefs, religion, human rights, end-of-life-care, informed consent, the law and euthanasia.

This subject was brought to international prominence earlier this year by the assisted suicide of David Goodall, a 104-year-old scientist from Australia. Although not suffering from a serious, discrete illness, he was aware of his diminishing abilities, including eyesight, and was told that he would eventually require round-the-clock care at home or go to a nursing home.

Goodall decided he didn’t wish to go on living beyond his 104 years, but euthanasia is currently illegal in Australia. So the eminent botanist and ecologist flew to Switzerland, where he was put to death with the aid of a euthanasia advocacy group.

Goodall's thoughts on the matter were very clear. He told Australia’s ABC News: “I'm not happy. I want to die. It's not sad particularly. What is sad is if one is prevented. My feeling is that an old person like myself should have full citizenship rights, including the right of assisted suicide.”

At the heart of the matter is an individual's right to choose how and how long to live. It should not be surprising that opinions are all over the map and raise some intriguing issues.

For everyone, thinking about our own decline with age, possible diseases we may get, and eventual death is depressing. We don’t want to be obsessed with dark thoughts about these uncomfortable subjects, but at some point we each need to think about them.

Physician-assisted suicide is just about the most uncomfortable subject imaginable. It is legal in seven jurisdictions in the U.S. – California, Colorado, the District of Columbia, Hawaii, Montana (with a court decision), Vermont and Washington state. But there are a number of limits on the practice. These include:

A terminal illness, meaning the person who wants to die is expected to live no more than six months.

Restrictions on who can write the prescription for the lethal drug.

Mandatory waiting periods and as many as three different consents by the person who wants to die.

Showing that the person who chooses assisted suicide is mentally competent.

It is the last of these that involves the strongest beliefs and loudest opinions – and the greatest obstacle for patients with Alzheimer's disease.

Alzheimer’s disease is widely regarded as one of the worst of all possible afflictions. Its progression and outlook are predictable and gruesome. It involves the erosion of a victim’s very identity.

There are no effective drugs to prevent or treat the disease. And Alzheimer’s takes an enormous physical, emotional and financial toll on patients and their families.

Also, Alzheimer’s kills slowly – taking on average four to eight years from diagnosis. This forces people with the disease and their families to endure different stages, each marked by a progressive decrease in their mental ability to reason, exercise judgment, understand what is going on around them and remember things.

By the end, people with Alzheimer’s barely resemble the people they once were. Many do not recognize their loved ones, think they are living in a different time period, and don’t know where they are.

Anyone who has spent time in a nursing home has seen what this terrible disease does to people. So it is not surprising that some people who have just been diagnosed with Alzheimer’s disease wish to end their lives before the deterioration becomes terminal. But when is that legitimate? When is it possible? This is where legal and ethical matters become very murky.

There are two diametrically opposite opinions about assisted suicide for people with Alzheimer’s. We do not judge them, but feel there is an interesting bit of logic that bears examining.

Under current state laws, it is impossible for someone with Alzheimer’s, regardless of the stage, to have the option of physician-assisted suicide. This is because of Catch-22 “safeguards” built into our laws that leave Alzheimer’s patients in a difficult situation.

The six-month rule

Where physician-assisted suicide is legal, state laws specify that a person who wants to die this way must have no more than six months to live.

While this requirement makes some sense for terminal cancer patients, it is problematic when applied to Alzheimer’s. When patients are in the early stages of Alzheimer’s they have far more than six months to live (absent any other risk factors). Six years would be far more common, so, under current state laws, Alzheimer’s patients cannot choose physician-assisted suicide.

Mental capacity

Unlike most other diseases, the very nature of Alzheimer’s guarantees that those afflicted cannot possibly be considered to be of sound mind when they are near death. They lack the capacity to make meaningful choices. This is where things get complicated.

In the early stages of Alzheimer’s, patients are lucid enough to make rational decisions about how or when to end their lives. But current laws automatically disqualify them from doing so because they are too healthy and most likely have several years, rather than less than six months, to live.

Once they are unable to reason, Alzheimer’s patients are barred from choosing assisted suicide, because they no longer meet the requirement to be of sound mind when choosing to die.

If the goal of physician-assisted suicide is to prevent unnecessary suffering, then why are Alzheimer’s patients and their families forced to suffer for years with no recourse, while people with a shorter-duration terminal disease that don’t impair their thinking have the right to choose their own fates? Does this make logical or medical sense?

We propose that this conundrum can be solved with an advance directive stating the individual’s wishes before the person is stricken with Alzheimer’s disease.

This would be analogous to the way that people can choose to refuse aggressive medical interventions – such as resuscitation from a cardiac arrest or admission to a hospital intensive care unit – near the end of life, by signing a document known as a living will (also called an advanced health-care directive).

A living will is a written statement of a person’s desires regarding medical treatment in cases where he or she is unable to give informed consent. Such documents allow the person to designate someone else – usually a loved one – to make these decisions.

For example, if a person is in a terrible car accident and doctors conclude that he or she is in an irreversible coma, a living will signed earlier by the accident victim could empower the designee to agree to the recommendation of doctors to withdraw life support.

For Alzheimer’s patients how would this work – in other words, what conditions would be imposed – in practice?

There are innumerable formulas that one could devise. For example, the criteria might include: certification of the diagnosis of advanced Alzheimer’s disease by a neurologist or gerontologist; consistent loss of awareness of person, place and time by the Alzheimer’s patient; and the inability to carry out activities of daily living (bathing, eating, taking medications, and so on).

A basic tenet of the medical profession is “first, do no harm.” Sometimes, the true sense of that requires that a patient’s wish not to suffer or lose dignity at the end of life be respected.

Josh Bloom holds a Ph.D. in organic chemistry and is the director of chemical and pharmaceutical sciences at the American Council on Science and Health.

Henry I. Miller, a physician and molecular biologist, was formerly a Consulting Professor at Stanford University’s Institute for International Studies and the founding director of the Food and Drug Administration’s Office of Biotechnology.