Dementia, by definition, is a decline in cognitive functioning from a previously higher level, in the presence of clear consciousness (i.e., not due to delirium) and is associated with impairment in functioning. As such, it can be rapid or slow in onset, and can be progressive or static in the cognitive impairment that ensues. Dementia has numerous causes, including traumatic brain injury, psychiatric illness (e.g., depression), vascular disease (e.g., stroke), vitamin deficiency, certain toxins, anoxia and neurodegenerative disease. The largest risk factor for dementia is advancing age, and among the elderly, dementia disproportionately affects women. This chapter reviews neurodegenerative dementia in late life and focuses on women. Epidemiology In 2013, an estimated 44.35 million individuals worldwide were living with dementia. This number is expected to double every 20 years, with between 115 and 135 million individuals living with dementia by 2050 (Prince et al., 2013; Alzheimer Disease International, 2013). The prevalence of dementia increases with advancing age, affecting an estimated 25% of individuals by age 85 (Ferri et al., 2005). The sex difference in dementia prevalence also increases with advancing age; roughly 5% of men and an almost equal percentage of women between ages 71-80 are diagnosed with dementia; after age 80, almost 28% of women and over 17% of men develop dementia (Plassman, et al., 2007). The type of dementia appears to account for the sex difference in prevalence rates. Among individuals older than 65 years of age, the most common cause of dementia is Alzheimer disease (AD), accounting for about 70% of cases (Alzheimer’s Association, 2011). Defined neuropathologically by the presence of intraneuronal neurofibrillary tangles, extracellular amyloid plaques, and neuronal cell death, AD disproportionately affects women. Two-thirds of patients with AD are women (www.alz.org/downloads/facts_figures_2012.pdf) and after age 80, the proportion of women with the disease (21%) is almost twice that of men (12%; Plassman et al., 2007). Although women generally live longer than men, women’s increased longevity is not sufficient to explain the 1.5 times greater likelihood of developing AD (Gao et al., 1998). Although the reasons why women are at greater risk than men for developing AD are not well understood, one possible explanation is that the disease appears to cause a more rapid global cognitive decline in women than it does in men (Ito et al., 2011).
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