Risk Factors for Dementia

Family history is also important. If you have a parent or sibling who has been diagnosed with AD, you are four times more likely to develop the illness. If two close relatives have AD, you are eight times more likely to have AD. This suggests that there may be a genetic, inherited basis for the disease. In fact, genetic studies have revealed that one-third or more cases of AD may be traceable to a genetic marker known as apolipoprotein E4. 

For unknown reasons, women are three times more likely than men to have AD. The rates for African-American women may be even higher that those for Caucasian women. 

Those with less education may be at greater risk for developing AD. It is unclear why this may be so. One theory is that extensive education may cause nerve cells to produce a more highly branched interconnected communication network. This in turn may provide duplicate backup circuitry in the brain that prolongs normal brain functioning even as brain cells progressively die. 

Other reported risk factors for AD include a history of depression, particularly late onset, exposure to aluminum, and being bom when your mother was older than forty. The evidence for the latter two risk factors is not as yet very convincing. 

The risk factors for vascular dementia are essentially the same as those for stroke and heart attack. They include high blood pressure, heart disease, diabetes mellitus, sickle cell disease, obesity, smoking, alcohol use, depression, and high cholesterol levels. 

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Cardiovascular and cerebrovascular disorders associated with lipid metabolism disturbance and atherosclerosis represent major risk factors for dementia (3,25,59). Atherosclerosis is the primary cause of heart disease and stroke in which genetic and environmental factors converge (553). More than 90% of patients older than 70-80 yr with dementia show signs of atherosclerosis in their arteries and a clear cerebrovascular component in their dementia process. It is very likely that pure AD is practically absent in octogenarians, in whom the prevalent diagnosis is vascular or mixed dementia (3,25,59), in which the APOE-4 allele also accumulates (18-20,554). 

Seshadri S, Beiser A, Selhub J, Jacques PF, Rosenberg IH, D Agostino RB, Wilson PW, Wolf PA. Plasma homocysteine as a risk factor for dementia and Alzheimer s disease. N Engl J Med 2002 346(7) 476-483. 

Jorm AF. Is depression a risk factor for dementia or cognitive decline A review. Gerontology 2000 46 219-227. 

Hyperhomocysteinemia has long been identified as a risk factor for dementia including Alzheimer s disease (AD) and vascular dementia (VaD) (Morris 2003). The relationship of homocysteine metabolism (methylation and transsulfuration pathways) to deficiencies of the vitamin B complex suggests that hypervitaminosis (Bg, B12 and folate) could contribute to hyperhomocysteinemia (Gonzalez-Gross et al. 2001). 

It is well-known that age is a risk factor for dementia and prevalence of dementia increases exponentially after 65 years age (Carr et al. 1997). AD is the most common cause of dementia in the elderly followed by vascular dementia (VaD) (Figure 46.2) (Fassenbender et al. 1999). 

Homocysteine. A sulfur containing non-proteinogenic amino acid synthesized from methionine. It is a risk factor for dementia and cardiovascular disorders. 

Ravalgia, G., Forti, P., Maioli, F., Maioli, F., Martelli, M., Servadei, L., Brunetti, N., Porcellini, E., and Licastro, F., 2005. Homocysteine and folate as risk factors for dementia and Alzheimer s disease. American Journal of Clinical Nutrition. 82 636-643. 

Wong MH, Robertson K, Nakasujja N, Skolasky R, Musisi S, Katabira E, McArthur JC, Ronald A, Sacktor N (2007) Frequency of and risk factors for HIV dementia in an HIV clinic in sub-Saharan Africa. Neurology 68(5) 350-355... 

Alzheimer s disease is the most common form of age-related dementia and one of the most serious health problems in the industrialized world. AD is an insidious and progressive neurodegenerative disorder that accounts for the vast majority of dementia and is characterized by global cognitive decline and the accumulation of P-amyloid deposits and neurofibrillary tangles in the brain. Family history is the second greatest risk factor for... 

Dementia is a major risk factor for delirium. Many illnesses may increase the risk of delirium. Infections, cardiac, metabolic and of course diseases in the central nervous system may all make elderly more vulnerable to delirium. Vision impairment and functional impairment are also well-known risk factors as well as premorbid cognitive impairment (Korevaar et al. 2005, Inouye et al. 2007). 

Korevaar JC, van Munster BC, de Rooij SE (2005) Risk factors for delirium in acutely admitted elderly patients a prospective cohort study. BMC Geriatr 5 6 Kudoh A, Takase H, Takahira Y et al. (2004) Postoperative confusion increases in elderly longterm benzodiazepine users. Anesth Analg 99 (6) 1674-1678 McCusker J, Cole M, Dendukuri N et al. (2001) Delirium in older medical inpatients and subsequent cognitive and functional status a prospective study. Cmaj 165 (5) 575-583 McCusker J, Cole M, Dendukuri N et al. (2003) The course of delirium in older medical inpatients a prospective study. J Gen Intern Med 18 (9) 696-704 McShane R, Areosa Sastre A, Minakaran N (2006) Memantine for dementia. Cochrane Database Syst Rev 19 (2) CD003154... 

Skoog I. (1979). Status of risk factors for vascular dementia. Neuroepidemiology. 17(1) 2-9. 

For many years, alterations in APOE and defects in the APOE gene have been associated with dysfunctions in lipid metabolism, cardiovascular disease, and atherosclerosis. During the past 25 years, an enormous amount of studies clearly documented the role of APOE-4 as a risk factor for AD, and the accumulation of the APOE-4 allele has been reported as a risk factor for other forms of dementia and CNS disorders (1,12,18-20,47.488). 

Table 10.1 shows the proposed risk factors for Alzheimer s disease, the most common cause of dementia. Heading this list is of course old age. But be careful how you... 

In addition to age, other factor s are associated with an inareased risk of AD. In developed countries, AD appears to be more common in v omen. Lack of education is a risk factor for senile dementia in China and Europe (Zhang et al., 1990 Schmand et al., 1997). Head daunra is also a risk factor for both sporadic (Mortimer et al., 1991) and familial AD (Guo et al., 2000). Silent myocardial infarcts and coronary stenosis triple the risk for AD (Aronson etal., 1990 Sparks etal., 1990), suggesting the importance of vascular risk factors. Other potential risk factors being studied include diabetes and hypertension (Ott et al., 1999 Peila et al., 2002 Qiu etal., 2005). As discussed below, a large number of genetic mutations are now associated with either early-onset AD or with increased risk of late-onset AD. 

Schmand B, Smit J, Lindeboom J, Smits C, Hooijer C, Jonker C, Deelman B (1997) Low education is a genuine risk factor for accelerated memory decline and dementia. J Clin Epidemiol 50 1025-1033. 

Wang F, So Y, Vittinghoff E, Malani H, Reingold A, Lewis E, Giordano J, Janssen R (1995) Incidence proportion of and risk factors for AIDS patients diagnosed with HIV dementia, central nervons system toxoplasmosis, and cryptococcal meningitis. J Acqnir Immune Defic Syndr Hum Retrovirol 8 75-82. 

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