Memory disorders result from damage to the neuroanatomical structures responsible for storing, retaining, and retrieving memories. Memory disorders may occur gradually, including Alzheimer's disease, or immediately, including those caused by head injury. Agnosia is the inability to recognize specific elements of objects, people, or sounds. Agnosia typically results from brain damage or neurological disorders. Treatment for agnosia varies depending on the location and cause of the damage. Recovery from agnosia is possible depending on the severity of the disorder and the severity of the brain damage. Agnosia can be diagnosed in more specific types, including: associative visual agnosia, stereopsis, auditory agnosia, auditory verbal agnosia, prosopagnosia, morphognosia, topographic disorientation, visual agnosia, and others. Alzheimer's disease is a type of progressive, degenerative, and fatal brain disease that involves the loss of connections between cells in the brain. Alzheimer's is the most common type of dementia. Alzheimer's disease (AD) affects approximately 1-5% of the world's population. The prevalence of AD is disproportionate between the sexes, with women being more affected. Evidence suggests that women with AD experience a greater degree of cognitive impairment than men with AD of the same age, and show a faster rate of cognitive decline. Amnesia is an abnormal mental state that affects memory and learning among other cognitive functions in an alert, responsive patient. There are two types of amnesia: anterograde amnesia and retrograde amnesia, which show damage to the hippocampus and medial temporal lobe. Individuals with anterograde amnesia have difficulty learning and retaining information when exposed to it after brain damage. Individuals with retrograde amnesia generally experience loss of memories for specific experiences or semantic information that is independent of context. Traumatic brain injury (TBI) is often the result of brain damage caused by an external force, and may lead to the development of amnesia depending on the severity of the injury. Head injury may result in temporary or permanent amnesia. In some cases, post-traumatic amnesia develops without retrograde amnesia, but this is more common in cases of penetrating brain lesions. Damage to the anterior temporal or frontal regions can be associated with the development of heterogeneous retrograde amnesia. Studies have shown that patients who have suffered a head injury have an accelerated state of forgetting of information learned during PTA. However, forgetting rates have returned to normal after PTA. Traumatic brain injury, as mentioned above, is associated with memory impairment; however, Alzheimer’s disease also carries several risks when it comes to aging. There is evidence to support a high rate of falls among the elderly, which is one of the leading causes of death associated with TBI in individuals aged 75 years or older. Looking at the graph on the right, it can be seen that falls account for only 28% of all TBI-related causes, indicating that the elderly constitute a significant portion of this proportion. Another factor associated with TBI and aging is the relationship between the duration of the injury and the age at which it occurred. It is estimated that the need for assistance after a TBI increases with age. In some cases, individuals have reported a distorted memory of images or sounds experienced specifically shortly before the injury, during the period of regaining consciousness, or during the conscious transition period between the actual injury and the onset of the TBI. As a result, this issue has raised controversy regarding the possibility that PTSD symptoms may be a result of severe head injury and memory loss. Patients in a study by McMillan reported experiencing “windows” of emotional distress that precipitated the development of PTSD. These “windows” included recalling events close to the impact, traumatic events that occurred immediately after the injury, or “islands” of memory. Brain injuries may also develop as a result of a stroke caused by anoxia that damages the site of the cerebrovascular accident. The effects of a stroke on both the right and left hemispheres of the brain include both short-term memory disturbances and difficulty acquiring and retaining new information.