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exegesisme exegesisme
wrote...
Posts: 60
Rep: 2 0
7 years ago Edited: 7 years ago, bio_man
How Do You Think About The 90+ Study?

The major findings are as following:

•People who drank moderate amounts of alcohol or coffee lived longer than those who abstained.
•People who were overweight in their 70s lived longer than normal or underweight people did.
•Over 40% of people aged 90 and older suffer from dementia while almost 80% are disabled. Both are more common in women than men.
•About half of people with dementia over age 90 do not have sufficient neuropathology in their brain to explain their cognitive loss.
•People aged 90 and older with an APOE2 gene are less likely to have clinical Alzheimer’s dementia, but are much more likely to have Alzheimer’s neuropathology in their brains.
- See more at: http://www.mind.uci.edu/research/90plus-study/
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wrote...
Valued Member
Educator
7 years ago
Interesting. If you get a chance, read the actual study, namely the comments sections:

Link: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4454472/

Why are you interesting this study exactly?

Our cross-sectional study found a strong dose-dependent association between poor physical performance and dementia in the oldest old, with higher odds of dementia associated with poorer physical performance. The results reveal that even modest declines in physical performance are associated with increased odds of dementia. The strongest association is seen with gait slowing, followed by 5 chair stands, grip strength, and standing balance. These associations remain essentially unchanged after adjustment for several confounders.

Our results are consistent with other cross-sectional analyses5,6,8,20,21 that found a significant association between poor physical performance and poor cognitive function in younger elderly individuals, although methodologic differences between our study and other cross-sectional analyses make direct comparison challenging. Most studies found an association between slower gait and cognitive impairment measured on tests of global cognition8,21 and the Clinical Dementia Rating Scale.20 One study6 found that cognitive impairment was also associated with weaker grip strength in addition to gait slowing. Furthermore, a similarly linear, dose-response relationship between gait speed and performance on tests of global cognition, memory, and attention was also found by some studies.5,8,21

In addition to the cross-sectional analyses, prospective studies have also reported an association between poor physical performance (including walking, balance, chair stand, and grip strength)9 or neurologic gait abnormalities10 and the development of all-cause9 or vascular dementia.10 Another study11 has shown that gait slowing was associated with the development of persistent cognitive impairment (Clinical Dementia Rating Scale score ≥0.5). Furthermore, gait slowing was a predictor of decline in several geriatric outcome measures, such as global health, falls, and new difficulties with activities of daily living.22

Although all measures of physical performance (4-m walk, standing balance, repeat chair stand, and grip strength) were associated with dementia in our study, slow walking had the highest odds of dementia among all physical performance measures.

Gait requires a seamless coordination of several neurologic systems, including motor, sensory, and cerebellar activities, which may explain in part why it showed the strongest association with dementia. In one prospective study, slow walking preceded measurable cognitive dysfunction by a mean of 3.7 years,11 suggesting that gait impairment is a risk factor for dementia. Although gait impairment is highly associated with large vessel strokes, adjustment for history of strokes and transient ischemic attacks did not change the results significantly. This result is somewhat counterintuitive; however, it could be explained by the low prevalence of large vessel strokes in our cohort. In The 90+ Study, large vessel strokes only accounted for 8.6% of all cerebrovascular events.23 It is therefore likely that in our cohort, the relationship between poor physical performance and dementia is not mediated by large vessel strokes but other factors, such as frailty and physical inactivity, that are not accounted for in this study.

We were concerned about the potential bias of only including participants with complete physical performance data in the main analyses. However, the inclusion of the participants with incomplete data in the secondary analyses only had minimal effect on the results of the main analyses. The negligible change in odds ratio in the secondary analyses suggests that results of the main analyses are stable estimates of the odds of dementia in relationship to poor physical performance in the oldest old.

There are multiple potential explanations for the observed association between poor physical performance and dementia. One explanation could be that a neurodegenerative process or combination of processes leads to motor and cognitive decline but the impairment of these functions is detected at different times. Cognition may not deteriorate as rapidly as physical performance, or individuals, especially those with high educational attainment, might be better at developing strategies to compensate for cognitive loss than for physical impairment. In addition, our methods of detecting subtle cognitive changes might be less sensitive compared with detecting changes in physical performance. If one process leads to impairment in both physical performance and cognition, subtle changes in gait and physical performance might serve as early markers for cognitive decline but may not be targeted as modifiable risk factors.

Another explanation of this association could be that decline in physical performance contributes to physical inactivity, which then leads to decline in cognition. Physical activity increases the levels of several classes of growth factors, including brain-derived neurotrophic factor24 and insulin like growth factor 1.25 At present, these factors are thought to play a key role in regulating the effects of exercise on learning.26 This hypothesis could imply that poor physical performance is a potentially modifiable risk factor for late-age dementia. This model is also supported by the modest success of exercise programs in improving cognitive function,27–29 although other studies30,31 did not find an effect.

To our knowledge, this is the first report examining the association between poor physical performance and dementia in the oldest old. The strengths of the study include a large sample of well-studied oldest old. In addition, the inclusion of several potential confounders bolsters the quality of the analysis. A limitation of our study, however, is the cross-sectional design, which precludes our ability to analyze the temporal relationship between poor physical performance and dementia. A longitudinal analysis of the relationship between physical performance and dementia in The 90+ Study is under way to evaluate whether poor physical performance precedes the development of cognitive loss in the oldest old. Another potential limitation is the difficulty of establishing the diagnosis of dementia in the oldest old, which can be challenging due to high rates of sensory limitations, fatigue, medical comorbidities, and limited participation in cognitively demanding activities. To address these limitations, we have modified our testing methods (eg, used larger print and provided sound amplifiers) and provided frequent breaks during evaluations. Furthermore, we modified our questionnaires to distinguish between functional loss due to cognition and functional loss due to physical reasons and whenever possible obtained additional information regarding functional loss from informants. Despite these challenges, we have extensive experience in diagnosing dementia in the oldest old. Our dementia diagnosis from the neurologic examination has a sensitivity of 94.6% and a specificity of 86.3% compared with the diagnosis obtained from a multidisciplinary consensus conference that used all available information (neuropsychological evaluations, informant questionnaires, medical records, and laboratory results) (M.M.C., unpublished data, 2012). Additional details of the diagnostic challenges and strategies of dementia in the oldest old are described in a recent publication.32 A further limitation of this study is the homogeneous demographics of our sample. However, a recent report by the US Census Bureau33 suggests that the participants of The 90+ Study are fairly representative of the oldest old in the United States, especially regarding sex (76% female) and ethnicity (88% white). A significant difference of our study participants, however, is the higher educational attainment of The 90+ Study participants. More than twice as many of our participants completed education beyond high school compared with the national average.33 Thus, more research is needed to determine the generalizability of our findings to other populations.

In summary, similar to younger elderly populations, our study found that poor physical performance is associated with increased odds of dementia in the oldest old. The establishment of this association may serve as a major stepping stone to further investigate whether poor physical performance is in the causal pathway and a potentially modifiable risk factor for late-age dementia.
exegesisme Author
wrote...
7 years ago
My interesting point in this study is

•People who were overweight in their 70s lived longer than normal or underweight people did.
wrote...
Valued Member
Educator
7 years ago
My interesting point in this study is

•People who were overweight in their 70s lived longer than normal or underweight people did.

It's just a correlation; we don't know the underlying reason for it. I don't like correlational studies. Correlational studies often lack the active manipulation of the independent variable(s). Pile of Poo
exegesisme Author
wrote...
7 years ago Edited: 7 years ago, exegesisme
My interesting point in this study is

•People who were overweight in their 70s lived longer than normal or underweight people did.

It's just a correlation; we don't know the underlying reason for it. I don't like correlational studies. Correlational studies often lack the active manipulation of the independent variable(s). Pile of Poo
I know what you mean. But it provides a valuable clue for farther active study. And practically, the overweight seniors needn't worry too much about their weight at this time.
wrote...
Valued Member
Educator
7 years ago
And practically, the overweight seniors needn't worry too much about their weight at this time.

That is true, but countless studies show that exercises boost immune function too, so we can't discredit those studies either.
exegesisme Author
wrote...
7 years ago
I already said no truth of science. Do I ask you repeat what I said?
wrote...
Valued Member
Educator
7 years ago
This is a *correlational study*, this is not based on an experiment.
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