normal. As noted in the above-mentioned section on traumatic brain injury it can be associated with memory impairment, Alzheimer's disease; however, as far as aging is concerned it poses other threats as well. There is evidence that supports a high incidence of falls among the elderly population and this is a leading cause of TBI-associated death among the population of people 75 years of age and older. When looking at the chart to the right on the page, it states that falls are only 28% of the total causes of TBI, so that would suggest that the elderly make up a good portion of that 28% overall. Another factor associated with TBI and age is the relationship between when the injury was sustained and the age at which it occurred. It is estimated that the older the individual, the more likely they would require assistance post TBI. In some cases, individuals have reported having a particularly vivid memory for images or sounds occurring immediately before the injury, on regaining consciousness, or during a lucid interval between the injury and the onset of PTA. As a result, recent controversy has emerged about whether severe head injury and amnesia exclude the possibility of post-traumatic stress disorder (PTSD) symptoms. In a study carried out by McMillan (1996), patients reported ‘windows' of experience, in which emotional disturbance was sufficient to cause PTSD. These 'windows' involved recall of events close to impact (when RA was brief), of distressing events soon after the accident (when PTA was short), or of 'islands' of memory (e.g. hearing the screaming of others). Brain injuries can also be the result of a stroke as the resulting lack of oxygen can cause damage to the location of the cerebrovascular accident (CVA). The effects of a CVA in the left and right hemispheres of the brain include short-term memory impairment, and difficulty acquiring and retaining new information. Dementia Dementia refers to a large class of disorders characterized by the progressive deterioration of thinking ability and memory as the brain becomes damaged. Dementia can be categorized as reversible (e.g. thyroid disease) or irreversible (e.g. Alzheimer's disease). Currently, there are more than 35 million people with dementia worldwide. In the United States alone the number of people affected by dementia is striking at 3.8 million. While studies show that there are “normal” aspects to aging, such as graying hair and changes in vision, there