Amnesia refers to the loss of memories, such as facts, information and experiences. Amnesia generally doesn't cause a loss of self-identity. People with amnesia — also called amnestic syndrome — are usually lucid and know who they are, but may have trouble learning new information and forming new memories.

Amnesia can be caused by damage to areas of the brain that are vital for memory processing. Unlike a temporary episode of memory loss (transient global amnesia), amnesia can be permanent.

There's no specific treatment for amnesia, but techniques for enhancing memory and psychological support can help people with amnesia and their families cope.

The two main features of amnesia are: Impaired ability to learn new information following the onset of amnesia (anterograde amnesia), Impaired ability to recall past events and previously familiar information (retrograde amnesia).

Most people with amnesia have problems with short-term memory — they can't retain new information. Recent memories are most likely to be lost, while more remote or deeply ingrained memories may be spared. Someone may recall experiences from childhood or know the names of past presidents, but may not be able to name the current president or remember what month it is or what was for breakfast.

Isolated memory loss doesn't affect a person's intelligence, general knowledge, awareness, attention span, judgment, personality or identity. People with amnesia usually can understand written and spoken words and can learn skills such as bike riding or piano playing. They may understand they have a memory disorder.

Amnesia isn't the same as dementia.                                                                                                                         Dementia refers to a group of progressive or chronic diseases characterized by a gradual decline in mental abilities that are severe enough to interfere with daily life.  Due to the social, physical, psychological and financial consequences associated with dementia, it can be overwhelming for the patients and the caregivers alike. Moreover, the lack of awareness regarding this disease often results in delayed medical intervention, and this is particularly the case in developing countries. Dementia is widespread and expected to rise.

The number of deaths caused by Alzheimer’s disease is higher compared to deaths caused by breast cancer and prostate cancer combined. Moreover, 1 in 3 elderly people die because of some form of dementia.

A large proportion of individuals with dementia are over the age of 65 but it can also affect individuals below this age bracket. Dementia is not a normal part of aging and it’s probability increases with age.

Dementia is a worldwide issue most prevalent in the developing countries. 60% cases of dementia are found in low to middle income countries, primarily due to lack of awareness and resources. In the next 20 years, we may see the largest increase in dementia cases in China, India and sub-Saharan Africa.

Dementia is not a disease itself; it is an umbrella term for a broad number of diseases all categorized by similar symptoms that include memory loss, disorientation, hallucinations and communication difficulties.

Dementia often includes memory loss, but it also involves other significant cognitive problems that lead to a decline in the ability to carry out daily activities.

A pattern of forgetfulness is also a common symptom of mild cognitive impairment (MCI), but the memory and other cognitive problems in MCI aren't as severe as those experienced in dementia.

Depending on the cause of the amnesia, other signs and symptoms may include:

False recollections (confabulation), either completely invented or made up of genuine memories misplaced in time confusion or disorientation.

Anyone who experiences unexplained memory loss, head injury, confusion or disorientation requires immediate medical attention.

A person with amnesia may not be able to identify his or her location or have the presence of mind to seek medical care. If someone you know has symptoms of amnesia, help the person get medical attention.

CAUSES.  Normal memory function involves many parts of the brain, and any disease or injury that affects the brain can interfere with the intricacies of memory.

Amnesia can result from damage to brain structures that form the limbic system, which controls your emotions and memories. These structures include the thalamus, which lies deep within the center of your brain, and the hippocampal formations, which are situated within the temporal lobes of your brain.

Amnesia caused by brain injury or damage is known as neurological amnesia. Possible causes of neurological amnesia include: stroke, encephalitis as a result of infection with a virus such as herpes simplex virus, as an autoimmune reaction to cancer somewhere else in the body (paraneoplastic limbic encephalitis), or as an autoimmune reaction in the absence of cancer, lack of adequate oxygen in the brain, for example, from heart attack, respiratory distress or carbon monoxide poisoning, long-term alcohol abuse leading to thiamin (vitamin B-1) deficiency (Wernicke-Korsakoff syndrome), tumors in areas of the brain that control memory, degenerative brain diseases, such as Alzheimer's disease and other forms of dementia, seizures certain medications, such as benzodiazepines.
Head injuries that cause a concussion, whether from a car accident or sports, can lead to confusion and problems remembering new information. This is especially common in the early stages of recovery. But head injuries usually don't cause severe amnesia.

Another rare type of amnesia, called dissociative (psychogenic) amnesia, stems from emotional shock or trauma, such as being the victim of a violent crime. In this disorder, a person may lose personal memories and autobiographical information, but usually only briefly.

RISK FACTORS. The chance of developing amnesia might increase if you've experienced: Brain surgery, head injury or trauma, stroke, alcohol abuse and seizures.

COMPLICATIONS
Amnesia varies in severity and scope, but even mild amnesia takes a toll on daily activities and quality of life. The syndrome can cause problems at work, at school and in social settings.

It may not be possible to recover lost memories. Some people with severe memory problems need to live in a supervised situation or extended-care facility.

TESTS AND DIAGNOSIS.

To diagnose amnesia, a comprehensive evaluation to rule out other possible causes of memory loss, such as Alzheimer's disease, other forms of dementia, depression or brain tumor is done. The evaluation starts with a detailed medical history. Because the person with memory loss may not be able to provide thorough information, a family member, friend or another caregiver generally takes part in the interview as well.

Issues that might be addressed include:

Type of memory loss — recent or long term, when the memory problems started and how they progressed, triggering factors, such as head injury, stroke or surgery, family history especially of neurological disease, drug and alcohol use, other signs and symptoms, such as confusion, language problems, personality changes or impaired ability to care for self and history of seizures, headaches, depression or cancer.

The physical examination may include a neurological exam to check reflexes, sensory function, balance, and other physiological aspects of the brain and nervous system.
Cognitive tests includes testing the person's thinking, judgment, and recent and long-term memory. Check the person's knowledge of general information — such as the name of the current president — as well as personal information and past events.

The memory evaluation can help determine the extent of memory loss and provide insights about what kind of help the person may need.

Diagnostic tests. Imaging tests — including MRI and CT scan — may be ordered to look for damage or abnormalities in the brain. Blood tests can check for infection, nutritional deficiencies or an electroencephalogram may be ordered to look for the presence of seizure activity.

TREATMENTS AND DRUGS

Treatment for amnesia focuses on techniques and strategies to help make up for the memory problem.

Occupational therapy. A person with amnesia may work with an occupational therapist to learn new information to replace what was lost, or to use intact memories as a basis for taking in new information.

Memory training may also include a variety of strategies for organizing information so that it's easier to remember and for improving understanding of extended conversation.

Technological assistance

Many people with amnesia find it helpful to use smart technology, such as a smartphone or a hand-held tablet device. With some training and practice, even people with severe amnesia can use these electronic organizers to help with day-to-day tasks. For example, smartphones can be programmed to remind them about important events or to take medications.

Low-tech memory aids include notebooks, wall calendars, pill minders, and photographs of people and places.

No medications are currently available for treating most types of amnesia.

Amnesia caused by Wernicke-Korsakoff syndrome involves a lack of thiamin. Treatment includes replacing this vitamin and providing proper nutrition. Although treatment, which also needs to include alcohol abstinence, can help prevent further damage, most people won't recover all of their lost memory.

LIFESTYLE AND HOME REMEDIES

Because damage to the brain can be a root cause of amnesia, it's important to take steps to minimize your chance of a brain injury. For example:

Avoid excessive alcohol use. Wear a helmet when bicycling and a seat belt when driving. Treat any infection quickly so that it doesn't have a chance to spread to the brain. Seek immediate medical treatment if you have any symptoms that suggest a stroke or brain aneurysm, such as a severe headache or one-sided numbness or paralysis.

Living with amnesia can be frustrating for those with memory loss, and for their family and friends, too. People with more-severe forms of amnesia may require direct assistance from family, friends or professional caregivers.