Risk of Mild Cognitive Impairment Higher in Former NFL Players
Previous research has suggested that retired American football players may have an increased risk for late-life cognitive disorders, although it has not yet been definitively established. Christopher Randolph, PhD, Clinical Professor of Neurology at Loyola University Medical Center in Chicago, and colleagues compared the likelihood of decline in cognitive function, including mild cognitive impairment (MCI), among retired American football players and older adults who had not played professional sports.
In 2001, all retired NFL players who belonged to the NFL Players’ Association (n = 3,729) were mailed a general health survey. In 2008, an additional survey specifically focusing on memory issues (including an Alzheimer’s disease screening questionnaire known as the AD8) was sent out to all players older than 50 who responded to the first survey. A total of 513 follow-up surveys were returned with the AD8 completed by both the former player and his spouse. The mean age of all the players who responded was 61.
Slightly more than 35% of respondents had an AD8 score that suggested possible dementia. By comparison, according to the Alzheimer’s Association 2011 Facts and Figures report, among Americans 65 and older, one in eight (13%) has Alzheimer’s disease.
The researchers used the follow-up survey data to identify former players with probable MCI. After additional telephone screening interviews to confirm likely cognitive change, eligible respondents were brought in for extensive testing at the Center for the Study of Retired Athletes at the University of North Carolina, Chapel Hill.
The researchers compared the neuropsychological test results for the former athletes with those of two other groups with no background playing professional sports—41 demographically similar adults with no cognitive changes and a clinical sample of 81 people diagnosed with MCI.
The researchers found that the former athletes were clearly impaired, compared with the demographically similar nonathletes. Because the two groups were similar except for the athletes’ professional sports background, this finding suggests that football may have played a role in the athletes’ impairment.
The athletes with MCI had test results similar to the other adults with MCI, except that the athletes were slightly less impaired. The athletes were also significantly younger, on average, than their nonathlete counterparts with MCI.
“It appears that there may be a very high rate of cognitive impairment in these retired football players, compared to the general population,” Dr. Randolph said. “These findings support the hypothesis that repetitive head trauma from many years of playing American football may result in diminished brain reserve and lead to the earlier expression of age-related neurodegenerative diseases such as MCI and Alzheimer’s disease. However, additional studies are necessary to confirm this conclusion. These results should be considered preliminary.”
Advancing the Global Standardization of Biomarkers for Alzheimer’s Disease
Kenji Ishii, MD, of the Tokyo Metropolitan Institute of Gerontology, and colleagues analyzed data from three multicenter studies of Alzheimer’s disease that are using a harmonized protocol—the Alzheimer’s Disease Neuroimaging Initiative (US-ADNI), Australian Imaging Biomarker and Lifestyle Flagship Study of Aging (AIBL), and Japanese Alzheimer’s Disease Neuroimaging Initiative (J-ADNI)—to evaluate the influence of apolipoprotein E (APOE) ε4 and age on the accumulation of amyloid in the brain as measured by PET scan with 11C-Pittsburgh compound B (PiB). This is the first report of an international ADNI data analysis including these three different national populations, all of which include people with Alzheimer’s disease, people with mild cognitive impairment (MCI), and cognitively normal individuals.
The researchers found that:
•The effect of age and APOE ε4 on amyloid deposition in the Japanese population is similar to Caucasians, despite a lower ε4 allele frequency in the Japanese population.
•In the cognitively normal people in the study, having a single copy of the APOE ε4 gene is roughly equivalent to 12 additional years of age for PiB positivity.
•The results suggest that the three multinational ADNI data sets are feasible for combined analysis.
“This is one of the first demonstrations of the great value of open data sharing in the worldwide ADNI initiative,” Dr. Ishii said. “Combined analysis enlarges and diversifies the study population and the data set. It increases the power of the results, decreases ethnicity effects, and makes the findings more broadly applicable. This is very important as we identify and verify biomarker tests for Alzheimer’s disease.”
In a second study, as the first phase in the standardization process for assessing hippocampal volume, Giovanni Frisoni, MD, of San Giovanni di Dio Fatebenefratelli, Brescia, Italy, and colleagues surveyed the various available segmentation protocols to identify underlying reasons why they result in different volume estimates. These protocols differ, because they rely on various techniques of segmentation—that is, assigning the electronic image voxels (volumetric pixels) to specific structures, such as the hippocampus, within the brain.