Why Focus on Alzheimer’s Disease?
So it’s a given that there are more elderly people on earth today than there ever have been in the past. As we age, we all experience a decline in memory. Often our ability to reason as quickly as we once did also takes a downhill route. Many diseases rear their ugly heads as we age. Of these diverse diseases, those affecting our ability to think, reason and remember are among the most devastating because they take away our past, our present and our future. These are the neurodegenerative diseases, of which Alzheimer’s is considered to be the most common. Currently the risk of Alzheimer’s dementia for someone who is 65 years of age is around 10%. When we look at the situation worldwide, the implications of this percentage are staggering. Around the globe in 2005 there were over 25 million with the disease. More to the point, these numbers are increasing with each passing year. The number of people with Alzheimer’s disease globally is projected to reach almost 120 million by the middle of this century as detailed below.
The Epidemic by the Numbers
We know that Alzheimer’s is not caused by a contagious agent—it is, however, directly related to aging. Since the growth rate of elderly populations is the greatest in history, then it follows that the number of cases of will also be the most that have ever been on this planet at a single time. If we look at the incidence of Alzheimer’s disease in relation to age, we see that about 3% of the world population between the ages of 65 and 74 suffers from the disease. This number increases to 14% of individuals aged 75–84. For those who live to the age of 85 and beyond, the number of people with Alzheimer’s disease reaches close to half (47%) of those in their age group. Some estimate that if we could live to 130 years of age, everyone would develop the disease.
In terms we can all relate to, it is estimated that a 65-year-old has a greater than 10% chance of developing Alzheimer’s disease. As we throw out these numbers, it is important to note that they are all estimates. It is impossible to have exact numbers because not all cases have been verified (e.g., by post-mortem autopsy) and not all cases are reported. Also, different groups studying the relationship of age and Alzheimer’s disease use different criteria to diagnose the disease. As a result they each arrive at different numbers. Looking at this in a different light, it is possible some groups overestimate numbers. Why? It is because simple but major memory decline often is listed as Alzheimer’s disease when it is not. This overestimation occurs when appropriate criteria, such as the presence of Alzheimer’s-specific biomarkers, are not applied. Also, in the past such evaluations were not so easily made and the attributes of true Alzheimer’s disease were not fully recognized; other neurodegenerative diseases were grouped under the same large umbrella. Regardless of any inconsistencies in generating the aforementioned numbers, there is no doubt that the upcoming Alzheimer’s epidemic is real and a few percentage points here or there are not going to make that epidemic any less severe.
So the numbers that are presented in this book are numbers that have been proposed by many different established and respected groups who are in the know. That said, when we toss out a number like 47%, as we did above for the incidence of Alzheimer’s disease in individuals 85 and older, it is just an estimate. Just like a poll of voters about their choice of politician, it gives us some idea of the current situation but it is a number that will only be verified with time. These numbers are meant to provide some insight into specific aspects of the disease but in reality whether that number is 47, 43 or 52 is up for debate. For the most part, we’ll err on the side of caution in presenting such data.
Demographics Play a Big Part
There is another side to the aging population coin. As summarized in Figure 2.1, not only is the number of elderly individuals increasing but also the number of newborns (children) is decreasing. As the following graph shows, internationally the percentage of children in the world has dropped significantly from the 1950s to today. This decrease is projected to continue at least until the middle of this century. In contrast there has been a steady increase in the number of seniors. More to the point, as seniors continue to live longer; there is a projected sharp increase in their percentage of the population as we move towards the year 2050.
Figure 2.1. The number of children worldwide is decreasing while the number of seniors is increasing.
Because of this increased longevity, those suffering from Alzheimer’s will also be around much longer than in the past, adding further to the problem. All of these factors mean the progressive and uncontrolled march towards the epidemic will continue. While estimates vary as mentioned, without question they do reflect the danger of the problems we will face. It is projected that the number of people living with dementia worldwide will almost double every 20 years. At present it is estimated that there are almost 5.5 million people with Alzheimer’s disease in the US alone. This number is projected to reach almost 14 million by the year 2050. Worldwide the numbers show a similar development as reflected in the following graph (Figure 2.2).
Figure 2.2. Estimates of the current and future numbers of Alzheimer’s disease individuals worldwide.
In 2006, globally there were about 27 million individuals suffering from Alzheimer’s disease. In keeping with the issue of getting accurate numbers as discussed above, some biomedical researchers argue this number is a low estimate. They instead suggest there are currently 50 million people worldwide suffering from the disease. This number is expected to increase almost four-and-a-half times by the middle of the century. By that time, using the conservative guesstimate, approximately 120 million people around the world will be diagnosed with Alzheimer’s disease.
In Canada, the number of cases of Alzheimer’s disease is projected to more than double within the next 25 years. At present over half a million Canadians suffer from Alzheimer’s. More than 71,000 sufferers are younger than 65 years of age. Things don’t look good for the future because currently a new case of is diagnosed every five minutes. Within 25 years or so, that number is expected to increase with a case of Alzheimer’s disease being diagnosed every two minutes. Similar numbers have been reported for other countries. For example, currently in Australia there are approximately 270,000 people suffering from Alzheimer’s disease. This number is projected to reach one million by 2050.
If you think about those numbers, it will immediately become clear that not only are the implications to the individual devastating but the significance to society is equally compelling. The increasing cost to healthcare alone is almost incomprehensible.
Different Countries, Different Problems
But there is another aspect to the increasing Alzheimer’s epidemic. Less-well-off countries are going to pay a higher price because the number of people with the disease will be greater in those countries. Data have revealed that the development of Alzheimer’s disease is directly linked to economics. Individuals from poorer countries are more likely to suffer from it than those from well-off countries. The data presented in Figure 2.4 summarize this information. As time passes, about five times more individuals will develop Alzheimer’s in low- to middle-income countries compared to those in better-off countries.
Figure 2.3. The number of individuals with Alzheimer’s disease varies based on the country’s income. (Modified from: Wortman