of the text. Most of this content will be easy to grasp by anyone but, at times, it will be necessary to delve into areas that will require a bit more effort. In such cases separate sections designated as “FYI:” are provided for those who want more details about the topics being covered. In the end a complete understanding will emerge on what we currently know and what we don’t know about this devastating, life-altering disease.
Chapter 2
The Alzheimer’s Epidemic by the Numbers
As discussed in Chapter 1, many consider Alzheimer’s disease to be the most significant health and social crisis of this century. In other words, it is on the verge of reaching epidemic proportions that require immediate and serious attention. To paraphrase the American Heritage Dictionary, “an epidemic is any event or disease that spreads, grows or develops rapidly”. Alzheimer’s fits this definition because it is a worldwide disease that is spreading rapidly. Already the disease has reached close to epidemic levels—and it is projected to get much worse. As the most prevalent and one of the most severe brain diseases, the cost to individuals, families and societies everywhere on this planet will only increase over time. In this short chapter, we’ll look at some specific numbers that give insight into why Alzheimer’s disease is approaching epidemic proportions and, as a result, why its implications to society can’t be ignored.
The Aging Crisis
The baby boom has caught up with us. As we all know, those babies have not only grown up, they have begun to senesce. In certain areas, elderly people outnumber the young by a large majority. As some would put it, we are facing a dramatic demographic upheaval that has not occurred previously in human history. While the large number of people born between 1946 and 1964 are a major part of this problem, other factors have made the situation worse. First, people are living longer. Second, fewer babies are being born due to a decrease in human fertility around the world. As a result of the large post-war baby boom, senescing populations are set to dominate demographics worldwide. While many are doing a “Chicken Little” over this, suggesting impending doom on all fronts, others suggest that if handled properly such demographic changes can often open doors to increased prosperity. Our concern here is not about the economic or social implications of this aging demographic but what it means in terms of one disease: Alzheimer’s.
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
