Philosophical Society of Washington

Minutes of the 2,208th Meeting

President William Saalbach called the 2,208th meeting to order at 8:16 pm September 15, 2006 in the Powell Auditorium of the Cosmos Club.

The recording secretary read the minutes of the 2,206th meeting. They were approved after a short discussion.

Mr. Saalbach introduced the speaker of the evening, Mr. Richard Hodes, director of the National Institute of Aging of the National Institutes of Health. Mr. Hodes spoke on Growing Older – Challenges and Opportunities in Aging.


Aging research has implications for all of us, Mr. Hodes began. He pointed out that in 1900, life expectancy in the U.S. was in the late 40’s. By 1950, the life expectancy of women had reached 70. By 2000, the life expectancy of men reached about 75 and for women the early 80’s. Even more dramatic is the increase in the number of people over 85. In1940, they represented thin red lines on Mr. Hodes’s chart, now they are thick red lines. The increase in the number of the oldest people will have great implications in many areas.

NIA was formed in 1974 with a very broad mission, to support and conduct research on aging, to train and develop research scientists and provide research resources, and to disseminate information on health and research advances. They deal with three general areas, biology, Alzheimer’s disease, and reducing disabilities associated with aging.

About aging, he said there are many theories, including DNA damage, stress response, protein modification, mitochondrial dysfunction, cell senescence, and gene expression. Studies indicate genetic factors account for about 30 % of the variation in aging and environmental factors about 70%. A study of nematodes indicated that those with a mutation in the age gene live longer than others, 40-some days instead of 20-some days. Mice on restricted calorie diets live longer. Their survival curve plunges to 0 at 57 months, for the control it plunges to 0 at 40 months.

For humans, the probability of survival to 100 is highly related to having a sibling who did. People over 100 are the fastest growing segment of the population.

       Someone asked if longevity is related to the X chromosome. This is not known, he said, but it is known that it is not so in all species.

The probability of having Alzheimer’s Disease increases rapidly with age. Among those 65 – 74, it is 3%, for 75 – 84 it is 19%, and for those over 85, it is 47%. There are 4.5 million AD patients now, and the trends point to 14 million by 2050.

Does maintaining mental activity reduce it? Yes, but the question is, why. It could be those people have a greater reserve of intellectual ability so it takes longer for AD to manifest. There is, however, a detectable rate of generating new neurons in the brain, even in adulthood, and it’s possible that a history of generating neurons produces a beneficial effect.

They now divide people into four AD categories: normal, pre-symptomatic, mild cognitive impairment, and finally, AD. This provides a better basis for intervention.

Positron Emission Tomography (PET) imaging of amyloid deposits in AD versus normal people shows stark differences. PET scans can provide quantitative information on amyloid deposits in living subjects. Pseudo-color imaging sharply enhances those differences.

How do plaques form? Beta amyloid spans the membrane. Beta secretase and Gamma secretase can cut the protein. When they clip at two points, they produce an opening that is prone to produce the beta amyloid plaque.

There are also studies being done on early onset familial AD, with onsets from the 30’s to the 50’s. This variety families usually know they have. It has corollaries in chemistry, in the secretases. It is found in animals as well as humans; it is associated with memory loss in mice.

Correlates of AD include age, head injury, high blood pressure, cholesterol, homocysteine, diet (fat), education/brain reserve/occupation, exercise and social networks. Estrogen is now believed not to have a beneficial effect, although a few years ago it was thought that it did.

Donepezil does delay the progression from moderate cognitive dysfunction to AD. It is highly significant, but the effect only holds for the first 12 months.

The statin drugs appear to reduce the prevalence of AD substantially. Lovastatin reduced it by 60 percent and prevastatin almost as much. They also work in mice and dogs.

He described a study called the Nun Study. Nuns and some men in various orders committed themselves to study and donated their brains for study after death. Nuns graded on how much plaque they had varied enormously in how much dementia they had. What explained it was vascular disease. It seemed that affecting circulation in brain moderated effect of plaques.

He mentioned that NIA is currently recruiting subjects for clinical trials involving a number of chemicals. Interested parties can find relevant information at www.nia.nih.gov.

Disability among older Americans has been reduced. The raw number has gone up, but the number relative to the number in the age group is 74% of what it would have been without the decrease. This could be a fragile phenomenon, though, because disability rates in younger groups have actually increased slightly, largely because of obesity.

A study with surprising revelations was one to compare the drug, metformin, with a placebo and a lifestyle (diet and exercise) regimen. Metformin was quite effective, reducing diabetes by about 40% among people age 25 – 49. However, diet and exercise was equally effective. Furthermore, as age increased, metformin was less effective and diet and exercise more. Among people over 60 metformin had no effect and lifestyle reduced diabetes 71%.

In the question and answer period, Mr. Hodes refined his analyses of some of the studies discussed. He pointed out that the participants in the nun study were at different locations and most likely did not have the same diet. Also, he reported that the study found that complexity of syntax in writing samples from subjects’ early years was associated with Alzheimer’s’. About children of older parents living longer, he said that could be because the parents had better genes which enabled them to have children at an older age.


Mr. Saalbach thanked our speaker and presented a plaque commemorating the event. He made the parking announcement, announced the next meeting, and invited everyone to stay for the social hour.

Finally, he adjourned the 2,208th meeting at 9:48 pm to the social hour.

Attendance: 66
Temperature: 18° C
Weather: Cool and mild

Respectfully submitted,

Ronald O. Hietala
Recording secretary

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