64 Although similar associations between physical activity and find more dementia may be expected in the oldest-old, such evidence is extremely scarce. Preliminary analyses of the 90+ Study showed that impairment in measures of physical performance (such as timed walking, balance, and hand grip) were associated with increased risk of dementia.6 Nevertheless, data of the 90+ Study from

the 1980s associated late-life exercise with longevity, but not dementia.65 In order to assess fully the contribution of physical activity to risk Inhibitors,research,lifescience,medical of dementia in the oldest-old, exercise and activeness should be objectively evaluated in real time, years before the onset of dementia. This requires long prospective studies, which are currently unavailable. Lifestyle Similar to physical Inhibitors,research,lifescience,medical activity, other lifestyle-related factors have been associated with longevity. Those factors include eating habits reflected in body mass index (both being underweight and being obese increased the risk of mortality),66 alcohol consumption (more than 2 drinks per day reduced the risk of death by 15%),67 and caffeine intake (with a U-shaped mortality curve).68 None of these factors, however, were associated with prevalent dementia in the oldest-old.6 In summary, many of the risk and protective factors for dementia in the young elderly are not relevant for Inhibitors,research,lifescience,medical the oldest-old. Out of the reviewed factors,

only age was consistently associated with dementia in the oldest-old. Estrogen showed some association with dementia in the oldest, but this association was not consistent through all studies and dementia subtypes. The other factors—the

ε4 allele Inhibitors,research,lifescience,medical of the ApoE gene, physical activity, and healthy lifestyle—which were all associated with dementia in younger elderly, were not associated with dementia in the oldest-old. This difference Inhibitors,research,lifescience,medical supports the potential for differential neurobiology of AD and dementia in the oldest-old. Neurobiological Changes in Dementia of the Oldest-Old “Dementia” is a general term for a group of disorders, and the distinction between dementia subtypes is largely dependent on their underlying neuropathology. Hence, for the most part, the following discussion describes the associations between pathologies of specific dementia subtypes and the clinical manifestation of general dementia symptoms. The major pathological hallmarks of AD, extracellular deposits of amyloid protein which form because neuritic plaques and intraneuronal neurofibrillary tangles, are found with increasing frequency in advancing age.69 The age-related increases in AD pathologies, together with the increased incidence rates of dementia with age, suggest that the two are related. Recent studies, however, have shown that the association between the pathological features of AD and dementia is stronger in younger persons than in the oldest-old.