Rates of Dementia Falling in the United States
Recent evidence suggests the rate of dementia within the United States may actually be declining, but this appears to be somewhat paradoxical. During a time in which the life expectancy in the United States has increased to approximately 78 years of age, and since dementia in its various forms is often associated with greater levels of age, the rate reduction coupled with increasing life expectancy seems contradictory. Furthermore, the trend is not just found in the United States but in other developed countries within the world.
The rate reduction in dementia was reported in the issue of the New England Journal of Medicine published Feb. 11, 2016. The research, led by Sudha Seshadri at Boston University’s School of Medicine using the Framingham Heart Study participants, found the incidence of dementia has been declining quite dramatically since the mid 1970s, with an approximate reduction of 20% in the risk of acquiring dementia.
What has to be put in perspective is that this does not mean on an absolute level the number of new cases of dementia are declining. As the population continues to grow, and in particular as the 65-year old age group continues to grow, the number of cases of dementia will continue to increase dramatically and will place an increasing burden of caring for these individuals in the future. Furthermore, the fastest growing part of the population are those individuals who are 80 years of age and older. It is in this group the number of individuals who have dementia will continue to grow in absolute numbers.
So then, what is declining? It is the incidence, which is the rate of new cases of dementia. This is still very good news. The rate at which individuals are being diagnosed with dementia has increased due to a number of factors: better cardiovascular health and improved lifestyle changes. Furthermore, the average age at which individuals are being diagnosed with dementia has increased by five years, from 80 to 85 years of age. This is also further good news since many individuals are living longer and adding more functional and healthy cognitive years to their lives.
What is the reason behind the decline in rates of dementia? The authors of the study attribute improved cardiovascular healthcare leading to some of the improvements. Closer monitoring of cholesterol, improved attention to blood pressure and quicker and more prompt attention to vascular occlusions that may contribute to cognitive decline have been targeted as some of the areas of cardiovascular improvement. It is known that considerable damage, such as through unremitting cerebral vascular accidents (strokes), if not addressed promptly and effectively, could lead to significant cognitive decline. However, the researchers state that improvement in cardiovascular care is not the only thing that has been instrumental in the decline of the rate of dementia.
The research did not answer whether other important health interventions may have contributed to this decline in the incidence of dementia. For instance, there has been a decline in smoking, and this reduction in smoking could be important in the decline through warding off potential cardiorespiratory problems that are associated with decreased circulatory performance and reduced blood oxygenation. Furthermore, a reduction in toxic substances and oxidizing factors associated with smoking may also be important factors that play a role as well.
In addition, many older adults have become more aware of the need for regular exercise and the need for improved diets, and this could also play a role in the declining incidence of dementia. However, here again, the study failed to look at this and more needs to be said on this topic as well. One also has to be mindful of many of the lifestyle changes that could have been important in this decline. As the Baby Boomer generation continues to move into the older adult years, a cohort that has been better educated than previous cohorts and has been paying more attention to the importance of lifestyle as well, it will be interesting to see if the decrease in the incidence of dementia continues.
To further advance on the issue of a better educated cohort, education and lifetime cognitive activity, although not a panacea, appears to demonstrate an important preventative impact toward reducing the probability of future dementia. In a study examining health and retirement, people born to later cohorts that had higher education had approximately a 40% reduction in the incidence of dementia. Again, whether this was due strictly to higher education or to other factors that the cohorts had encountered that may have had a preventative impact is far from definitive.
However, even if this trend is due to current lifestyle changes, especially those that impact one’s cardiovascular health that may potentially contribute to the reduction in the incidence of dementia, one may have to wonder if this trend will continue and for how long. As issues of obesity and diabetes continue to demonstrate significant increases in our society, especially among younger groups that are currently not in the 65 and older cohort yet, and as younger generations have now started to adopt a more sedentary lifestyle with computerized technology pervading society, one has to wonder if the current reversal in the rate of dementia may be short-lived.
Although the news of the current decline in the incidence of dementia has to be met with great applause, one has to remember that the rate being measured does not reflect the growth in the total number of those that have dementia. Furthermore, as the population continues to age, those that reach older adult years, or what has often been referred to as the old-old part of the population, 85 years of age and older, will continue to encounter more dementia on an absolute level. This means that those in our society that suffer from dementia will continue to grow, and the growth will be in large numbers, concomitant with the increasing older adult population that will approximate 20% of the total population in the next 30 years.
Therefore, although the slowing in the incidence of dementia is very laudable, our country will continue to have to meet the ever-increasing needs of more individuals that will suffer from dementia, leading to an ever-increasing strain on family members and on our already exorbitantly costly healthcare system.
1. U.S. Dementia Rates Seem to Be Falling, Study Finds: Decades-long review revealed risk of brain disease is dropping, while age at diagnosis is going up (Feb 10, 2016). Available at: https://www.nlm.nih.gov/medlineplus/news/fullstory_157175.html
2. Falling Dementia Rates in U.S. and Europe Sharpen Focus on Lifestyle. Alzforum: Networking for a Cure (Feb 12, 2016). Available at: http://www.alzforum.org/news/research-news/falling-dementia-rates-us-and-europe-sharpen-focus-lifestyle
3. Dementia Incidence Said to Drop as Public Health Improves. Alzforum: Networking for a Cure (May 17, 2013). Available at: http://www.alzforum.org/news/research-news/dementia-incidence-said-drop-public-health-improves