Amnesia (abnormal memory loss conditions): an abnormal degree of forgetfulness; i.e. inability to retrieve old memories and/or inability to create new memories.

Amnesia is the abnormal memory loss caused by brain damage, disease, or psychological trauma that can occur at any age. Amnesia can be broadly categorized as organic or functional . Organic amnesia are the memory loss result from damage to brain due to infection, degenerative (brain) diseases, stroke or direct brain injury (for the influence of lifestyle factors, also see post ” Intrinsic and Extrinsic Causes of Age-Related Memory Loss”). Functional (or psychogenic) amnesia occurs as a result of traumatic psychological experience. An Alternative way to classify amnesia is based on the area of brain that are damaged or affected. Some major types of amnesia conditions are listed below:

• Transient global amnesia: rare, temporary, complete loss of all memory.
• Anterograde amnesia: inability to create new memory, especially recent events after the onset of amnesia
• Retrograde amnesia: inability to remember events preceding a trauma
• Dissociative amnesia (functional amnesia:psychogenic amnesia): the memory loss caused by psychological problems instead of direct brain injury

This list is not conclusive. There are also many rarer instances (types) of amnesia such as Wernike-Korsakoff’s psychosis (alcohol induced memory loss), Hysterical (fugue) amnesia (forget one’s identity), source amnesia (can not remember when and where they got the information), Prosopamnesia (can not identify face). Moreover, Combinations of anterograde amnesia and retrograde amnesia could occur in the same individual.

How do we tell the difference between amnesia symptoms and those of regular memory lapses and forgetfulness? More specifically, what is the distinction between amnesia and the memory problems we face as we age? How amnesia is linked to aging? While we all could forget something or have trouble recalling information from time to time. Particularly fatigue or stress can momentarily interrupt memory retrieval or memorization process. Normal memory interruptions i.e general memory lapses or forgetfulness are usually minor, temporary and will not interfere with day to day activities. This post “Normal Age-Related Memory Loss Types – Types of Forgetfulness or Memory Lapses” listed and discussed various types or phenomenons of regular or normal forgetfulness. Amnesia is a more complete memory loss. Amnesia of or caused by other age-related (degenerative brain) diseases tends to have a more lasting effect on short term and/or long-term memory. The most typical symptoms of amnesia are:

• difficulty or inability to learn new information (anterograde amnesia)
• difficulty or inability to recall past stuff
• false memories: either completely invented or misattributed
• confusion or disorientation
• partial or complete loss of memory
• fail to identify face and places
• vulnerable to interruption, can not resume a task if interrupted.

Some age-related (degenerative) brain disease or conditions of cognitive decline are associated with severe amnesia. These include Alzheimer’s disease, dementia and other cognitive decline or degenerative brain conditions. Alzheimer’s disease, dementia are important triggers and manifestations of severe Amnesia. Dementia categorizes a group of brain problems as a result of progressive deterioration in cognitive function (memory, language, problem solving and attention) associated with aging.  Symptoms may involve changes in personality, mood, and behavior in addition to declining cognitive functionality. Dementia develops when the parts of the brain responsible for learning, memory, decision-making, and language are affected by injury or disease. (lifestyle habits can exacerbate or accelerate this process. see post “Intrinsic and Extrinsic Causes of Age-Related Memory Loss”)

Alzheimer’s is the most common type of dementia that causes problems with memory, thinking and behavior. The disease is progressive, symptoms develop over time and gets worse and worse. The characteristic symptoms are the gradual loss of memory and other intellectual abilities serious enough to interfere with daily life. With late-stage Alzheimer’s, individuals can not start a conversation and respond to environment stimuli. Current treatment of Alzheimer’s treatments cannot cure the disease, however, they can temporarily slow the worsening of symptoms. The most prominent early signs of Alzheimer’s disease is the difficulty in remembering newly exposed  information.

Mild Cognitive Impairment (MCI) defines a transitional state between cognitive changes of normal aging and Alzheimer’s disease. People with MCI could have memory problems more frequent than average of the individuals within the same age group. People with MCI still can carryout normal activities and their symptoms are not as severe as that of Alzheimer’s disease. Studies have indicated that MCI individuals are at an increased risk for developing Alzheimer’s disease.

Many different types of dementia, although less common than Alzheimer’s disease, can be caused by many other causes (diseases). Dementia can be categorized by underlying causes or they can be divided into two categories based on the region of brain affected – cortical and subcortical dementias. Alzheimer’s disease if a form of cortical dementia. Dementias which sometimes caused by Parkinson’s disease are subcortical dementias.

• Vascular Dementia (impairment in drive blood flow to the brain) (e,g, stroke induced dementia and memory problem)
• Mixed Dementia (multiple causes)
• Dementia with Lewy Bodies (DLB) (abnormal protein deposits -Lewy bodies – in nerve cells in the brain stem)
• Parkinson’s Disease Dementia (PDD)
• Frontotemporal Dementia
• Creutzfeldt-Jacob Dementia (CJD)
• Normal Pressure Hydrocephalus (NPH)
• Huntington’s Disease Dementia
• Wernicke-Korsakoff Syndrome
• Mild Cognitive Impairment (MCI)

Some forms of dementia may improve greatly or can be completely cured when the underlying cause is treated. Non-curable causes of dementia include: Alzheimer’s disease, Vascular dementia, Dementias associated with Parkinson’s disease and similar disorders, AIDS dementia complex, Creutzfeldt-Jakob disease.  Best way to prevent age-related amnesia is to eliminate those lifestyle habits that may accelerated the brain aging process and exacerbates the situation if early signs of cognitive decline start showing up. Maintain a healthy lifestyle habits are crucial not just to prevent age-associated memory loss problem, but is important for healthy aging and overall wellness.