A new investigation studied over 21,000 U.S. adults 65 years or older to analyze their dementia prevalence between 2000 and 2012.

The research found that dementia cases declined from 11.6% in 2000 to 8.8% in 2012. A higher level of education and treatment of cardiovascular diseases might be the cause behind declining rates of U.S. adults suffering the condition. It also found that U.S. citizens 65 years or older had nearly one more year of education in 2012 compared to participants in 2000. Higher education was also associated to lower risks of suffering dementia.

Elderly adult/Senior
The study was published online in the Journal of the American Medical Association, and it was carried by Kenneth M. Langa, MD, Ph.D., Division of General Medicine at the University of Michigan. Image credit: New England Geriatrics.

Cardiovascular diseases are a risk factor for dementia, as other studies have proved. However, despite a significant increase of cardiovascular diseases between 2000 and 2012, the study found that better treatments for those conditions reduced the risk of dementia in the population considered in the research.

Langa and colleagues used data from the Health and Retirement Study, which is a biennial survey of U.S. adults that started in 2012. It collects a wide range of information on health, cognition, family, employment and health that was used in the research to test if the age-specific prevalence of dementia declined in America between 2000 and 2012.

Dementia causes a reduction in memory and mental ability that ultimately interferes with daily life. Dementia is mostly associated with memory loss. There are various types of the condition, including Alzheimer’s disease which accounts for 60 to 80 percent of dementia cases. Vascular dementia, which occurs after a stroke, is the second most common type of dementia.

Study details: Population, data collection

The study sample of 21,057 included all HRS participants 65 years or older living with their families or by themselves and those living in nursing homes between 2000 and 2012. The data used in the research included cognitive functions in self-respondents. Several tests came from the Telephone Interview for Cognitive Status (TICS).

The survey collected information on health, cognition, family, wealth and employment. It also included a psychological questionnaire, body measurements to calculate body mass index, physical performances and a blood and saliva sample of the participant. Other characteristics included in the paper were age, self-reported race/ethnicity —including white, black, Hispanic, or other— sex, and education.

The level of instruction was measured considering if the adult had less than 12 years of schooling, 12 years, between 13-15 years, or 16 or more years of education. Chronic medical conditions and cardiovascular risk factors included stroke, diabetes, heart disease, hypertension, and BMI.

Cognition was assessed on a scale of 27 points. A score of 0 to 6 indicating dementia, 7 to 11 indicating cognitive impairment no dementia (CIND) and those scoring 12 or more corresponded to normal cognition. Another test to measure memory and limitations in activities of daily living was also part of the study.

Less U.S. adults have suffered dementia between 2000 and 2012

After analyzing the data from the Health and Retirement Study, Langa discovered that fewer adults were suffering from dementia in 2012 compared to the cases reported in 2000, with a decrease of 2.8 percent. The prevalence of CIND also dropped during those years from 21.2 percent to 18.8 percent.  

When analyzing the differences in the level of instruction between the 2000 group and the 2012 group, the study showed that adults in the last sample had one more year of instruction than those adults in the first cohort. More years of education are related to brain development and functions and health behaviors, which could explain why adults with more years of instructions are less likely to suffer from dementia.

Elderly adult in a library
It is estimated that 4 to 5 million elderly adults in America are affected by the disease, which not only affects the patients but families and the economy of the country. Image credit: Dave Eggen.

The 2012 participants had higher chances of developing cardiovascular diseases than those participants from 2000. Obesity increased from 18.3 percent in 2000 to 29.2 percent in 2012. A similar trend happened with diabetes, (16.4 percent in 2000 vs. 24.7 percent in 2012), and hypertension (54.6 percent in 2000 vs. 67.6 percent in 2012).  Improvements in treatments for cardiovascular disease during those 12 years were linked to less risk of suffering from dementia.

New treatments developed between 2000 and 2012 to reduce common diabetes complications such as heart attacks, stroke and amputations are considered to be the factor that decreased dementia risk in American adults in the study. More data consulted from the HRS on diabetes showed that between 2000 and 2012, a higher number of adults used treatment for diabetes (86 percent against 90 percent) and achieved treatment goals.

The University of Michigan study is not the first one to point out that higher level of instruction and better treatments for cardiovascular disease contribute to dementia development. Its results are similar to past research but do not answer if the full set of social, behavioral and medical factors of the participants are directly contributing to the risks of the mental condition.

Source: JAMA