Dementia risk factors

Dementia risk factors

...Relative to nonsmoking, current smoking, past smoking, and pack-years were not significantly related to change in immediate memory. None was significantly related to change in orientation. Only pack-years was significantly related to normal change score in digit span (normal change score change per unit of predictor=0.001, 95% confidence interval 0.0003–0.002).
American Journal of Epidemiology Vol. 137, No. 8: 881-891, Oxford Journals


.....Alcohol and smoking (never, past and current) were neither strongly protective nor predictive. Poor self-perceived health (versus good) increased the risk for incident dementia (OR = 3.9, 95% CI = 2.2–6.9).

Risk factors for incident dementia in England and Wales: Oxford Journals



.........The authors assessed the association of smoking with dementia and cognitive decline in a meta-analysis of 19 prospective studies with at least 12 months of follow-up. Studies included a total of 26,374 participants followed for dementia for 2–30 years and 17,023 participants followed up for 2–7 years to assess cognitive decline. Mean study age was 74 years. Current smokers at baseline, relative to never smokers, had risks of 1.79 (95% confidence interval (CI): 1.43, 2.23) for incident Alzheimer's disease, 1.78 (95% CI: 1.28, 2.47) for incident vascular dementia, and 1.27 (95% CI: 1.02, 1.60) for any dementia.

A Meta-Analysis of Prospective Studies: American Journal of Epidemiology Advance Access originally published online on June 14, 2007; Oxford Journals




........Less educated patients became demented later and died later, but cognitive function declined at the same rate in all educational groups and there was no difference in the burden of neurodegenerative lesions between them. However, the less educated patients had more cerebrovascular lesions. It can be concluded that higher education does not modify the course of Alzheimer's disease, but lower education relates to the occurrence of cerebral infarcts. Our results suggest that a `brain battering' model related to the higher prevalence of small vascular lesions in less educated individuals may explain their increased risk of dementia described by epidemiological studies better than the prevalent `brain reserve' hypothesis.

An autopsy-verified study of the effect of education on degenerative dementia; Brain, Vol. 122, No. 12, 2309-2319, December 1999; OUP



........However, the basis for the relationship between low educational attainment and cognitive decline or poor performance on cognitive tests is not so clear. Underlying mechanisms have been proposed based on the functional brain reserve hypothesis. Yet it is widely accepted that lower levels of education are associated with diminished performance on tests of cognitive ability. This is a particularly relevant issue for studies with US immigrants, where low levels of formal education are highly prevalent and where cognitive assessment is usually done with instruments developed for populations with different education levels and culture. One study (2000) found that performance in normal individuals with no schooling was as low as that of subjects with severe dementia, whereas the score for those with 1 to 4 years of schooling was similar to that of subjects with slight dementia.

...............Most of the instruments used in survey studies have conventional cut-off scores originally used in their norming sample study or adapted for the purpose of each survey, but neither one considers different cut-off scores for the different educational levels. Cognitive impairment may be overestimated in Spanish-speaking subjects when conventional cut-off scores are used. Recently,we have found that the Mini-mental State Examination (MMSE) cut-off point of 23 or 24 in Mexicans with 5 years or less of formal education results in very low specificity values (23% to 28%), which means that a large amount of normal subjects with low educational level will be erroneously classified as cognitively impaired. This finding is in agreement with Gurland (1992), who suggested that conventional scores produce an increase in false positives for minority groups, especially Hispanics. Poor performance in Spanish-speaking populations has been attributed to low schooling and ethnic and cultural differences. One method aimed to identify subjects with cognitive impairment considering the effect of confounding variables such as education, is the use of percentile distribution obtained by ranking the data values in ascending order from lowest to highest score within each educational level. The percentile technique is appropriate for data with non-Gaussian distributions and is
commonly used to rank candidates in an examination. It provides an approach that can be used to evaluate individual subjects against the distribution of scores in a particular population.....

Comparative Analysis of Cognitive Impairment Among... Immigrant’s Elders;
http://jah.sagepub.com/cgi/reprint/18/2/292



According to widely circulated global burden estimates, unipolar depressive disorders are the leading cause of disability adjusted life-years (DALYs) in the Americas and the third leading cause in Europe. …Individuals living with others with poor mental health are also significantly more likely to report worse mental health themselves. In contrast, there is little observed relationship between mental health and poverty or education, common measures of socio-economic status. The results instead suggest that economic and multi-dimensional shocks such as illness or crisis can have a greater impact on mental health than overall levels of poverty. This may have important implications for social protection policy. The authors also find significant associations between poor mental health and lowered labour force participation (especially for women) and higher frequency visits to health centres, suggesting that poor mental health can have significant economic consequences for households and the health system. Finally, the paper discusses how measures of mental health are distinct from general subjective welfare measures such as happiness and indicate useful directions of future research.
…. However, it is also plausible that the relationship could be causal, whereby the presence of one household member with poor mental health creates a poor mental health environment for other household members, i.e. a “contagion” effect. Tables 2 and 3 show that there is indeed a strong and significant positive relationship between an individual’s mental health and that of his or her family.10 A one standard deviation change in the mental health of household members is associated with a 0.22 to 0.59 standard deviation change in own mental health.

….. There is evidence in some countries that lower mental health is associated with reduced labour force participation, especially for women. Mental health is also a significant predictor of health care utilization and thus perhaps burdens a health system ill-equipped to diagnose and provide care.
Mental Health Patterns and Consequences, Policy Research Working Paper 4495, The World Bank

- The association found between mental disability and Education may be explained by more logical approach to life events. Rather than years of education, the focus should be on taking account of emotional capacity in dementia and AD.
- Education years is not a satisfactory indicator, the trends for continuous mental ac-tivity need to be accounted for, to provide better example of the state of mind at the time of disease development.
- Protective factors in terms of healthy diet studies are so inadequate in their assess-ment and data to infer reliable conclusion, caused mostly due to inattention to take accurate account of food intake habits, and trends. This is particularly true for rare incidence of Alzheimer and dementia, which needs more thorough study particularly on those who did develop the disease. Who on the earth would measure daily intake of their fruit consumption, I wonder ?? the studies only find relevance where national eating habits are brought into account versus the regional prevalence of dementia.(me)

...........However, statistical significance says little about the magnitude or precision of an estimated association, and is especially misleading when its absence is misinterpreted as absence of an association. Absence of significance signifies only that the association was estimated too imprecisely to determine the direction with confidence, and often reflects more the limited size of the sample than the size of the association.
http://ije.oxfordjournals.org/cgi/content/full/32/4/553




OXFORD PROJECT TO EXAMINE MEMORY AND AGEING

The challenge
• Each year about 203,000 people in the UK develop dementia (550 every day), the great majority with Alzheimer’s disease.
• Alzheimer’s disease costs the country about £17 billion per year, which is almost 20% of the health budget. The costs of Alzheimer’s disease are more than the combined costs of heart disease, stroke and cancer.
• The main challenge is to discover ways of preventing Alzheimer’s disease from developing.


How is OPTIMA dealing with the challenge?

1. In 1992, OPTIMA introduced new methods of diagnosis of Alzheimer’s disease, in use around the world.

2. In 1994 OPTIMA discovered that Alzheimer’s disease is not an inevitable part of ageing, but that it is a true disease. This finding led OPTIMA to search for ‘risk factors’.

3. In 1998, OPTIMA discovered the first risk factor for Alzheimer’s disease that can be safely and simply modified by diet (homocysteine. This discovery was recognised by the American Medical Association as one of the most significant findings of the year. OPTIMA’s discovery has been confirmed world-wide and has led the US National Institute on Aging to set up a clinical trial in which B vitamins, which lower homocysteine levels, are being tested to see if they can slow the progression of Alzheimer’s disease.

http://www.medsci.ox.ac.uk/optima



Folate, Vitamin B12, and Serum Total Homocysteine Levels in Confirmed Alzheimer Disease

Recent studies suggest that vascular disease may contribute to the cause of Alzheimer disease (AD). Since elevated plasma total homocysteine (tHcy) level is a risk factor for vascular disease, it may also be relevant to AD.

Low blood levels of folate and vitamin B12, and elevated tHcy levels were associated with AD. The stability of tHcy levels over time and lack of relationship with duration of symptoms argue against these findings being a consequence of disease and warrant further studies to assess the clinical relevance of these associations for AD.

Serum tHcy levels were significantly higher and serum folate and vitamin B12 levels were lower in patients with DAT and patients with histologically confirmed AD than in controls. The odds ratio of confirmed AD associated with a tHcy level in the top third (>=14 µmol/L) compared with the bottom third (<=11 µmol/L) of the control distribution was 4.5 (95% confidence interval, 2.2-9.2), after adjustment for age, sex, social class, cigarette smoking, and apolipoprotein E {epsilon}4. The corresponding odds ratio for the lower third compared with the upper third of serum folate distribution was 3.3 (95% confidence interval, 1.8-6.3) and of vitamin B12 distribution was 4.3 (95% confidence interval, 2.1-8.8). The mean tHcy levels were unaltered by duration of symptoms before enrollment and were stable for several years afterward. In a 3-year follow-up of patients with DAT, radiological evidence of disease progression was greater among those with higher tHcy levels at entry.


http://archneur.ama-assn.org/cgi/content/full/55/11/1449



As researchers learn more about FTLD through MRI scans of patients' brains, Levenson said they will be better able to pinpoint the brain circuits responsible for certain emotions and promote awareness of what is a devastating and still misunderstood disease. Levenson said. "If you understand that emotional response changes result from a brain disease, you are likely to have a different reaction and be more supportive."

Levenson and Miller published an overview of their findings in the December 2007 issue of the journal Current Directions in Psychological Science after conducting intensive laboratory studies of FTLD patients that included brain scans, precise tests of emotional functioning, and interviews. While study participants reacted normally to very simple emotional stimuli, they lacked complex emotions such as embarrassment or compassion, and they had difficulty recognizing emotions in others.

"Embarrassment is an emotion that lets us know we have violated social norms and motivates us to take corrective actions. Without emotions such as embarrassment, we behave very inappropriately in social situations," Levenson said.

Compared to Alzheimer's disease, which is marked by dramatic memory loss and typically occurs in old age, frontotemporal dementia usually shows up before age 65 and is commonly mistaken for depression and other psychiatric disorders. At present, there is no effective treatment for FTLD.

FTLD affects as many as 15 percent of dementia sufferers, according to Levenson. The average time from diagnosis to death is five years. While it is unknown at what age FTLD actually begins, the symptoms usually appear in a person's 50s. Triggering the death of brain cells are proteins, such as tau, that accumulate in the neurons of the central nervous system. They particularly build up in the frontal and temporal lobes and literally smother the brain cells to death.

http://www.physorg.com/news127573514.html