What are the other Names for this Condition? (Also known as/Synonyms)

• Amnestic Syndrome
• Dementia-Memory Loss
• Mild Cognitive Impairment-Memory Loss

What is Amnestic Disorder? (Definition/Background Information)

• Amnestic Disorders include several conditions that cause problems in memory, which may either be the loss of previously remembered memories or inability to create newer ones
• Amnestic Disorder can occur as a consequence of a general medical condition, or be related to trauma or substance-use/abuse. In addition, Amnestic Disorders may occur with unknown causes as well, when they are termed Amnestic Disorder, NOS (not otherwise specified) and transient global amnesia, etc.
• Amnestic Disorder as a result of a traumatic brain injury (TBI) can occur in any individual. When the condition occurs due to substance abuse, it is often seen in young and middle-aged adults 
• Based on the type of memory loss, Amnestic Disorder is broadly classified into:
  • Retrograde amnesia: Difficulty recalling memories before the onset of the disorder
  • Anterograde amnesia: Inability to learn new facts or form new memories
  • Sense-specific amnesia: Loss of memory of events processed by a particular sense (such as taste, hearing, etc.)
  • Transient global amnesia: A temporary loss of mental functionality. Typically, the ability to recollect recent events and absorb new knowledge is lost. Episodes are sudden and generally do not extend beyond 24 hours in these cases
• Recurrent head trauma, conditions such as schizophrenia and bipolar disorder, drug and alcohol abuse, etc. are some risk factors for Amnestic Disorder.
• The signs and symptoms of Amnestic Disorder range from confusion and bewilderment, to personality changes and false memories (to fill the gaps in memories)
• While patients with transient global amnesia may recover early, other disorder types may require treatment measures that include medication and rehabilitation
• In many cases, the type of trauma that caused the condition determines the prognosis for Amnestic Disorder. Some individuals with memory loss caused by TBI or substance abuse may not recover completely

Who gets Amnestic Disorder? (Age and Sex Distribution)

• Amnestic Disorders related to head injuries may affect individuals of any age group
• However, according to the statistics of traumatic brain injuries (TBI), there are certain groups of individuals who are more at risk for TBI than others, including:
  • Children up to 4 years of age
  • Older adolescents aged 15 to 19 years
  • Adults aged 65 years and older
  • In every age group, TBI rates are reportedly higher for males 
• According to study reports, adults, 75 years and older, have the highest rates of severe TBIs that result in hospitalizations
• Amnestic disorders caused by abuse of drugs other than alcohol are most common in people between the ages of 20 and 40 years
• Transient global amnesia usually appears in people over 50 years of age

What are the Risk Factors for Amnestic Disorder? (Predisposing Factors)

The following are some known risk factors for Amnestic Disorders:

• Recurring head trauma, such as those experienced by a boxer or a football player
• A traumatic experience that may take place during any of the following:
  • Accident
  • War
  • Genocide
  • Sexual or physical abuse
  • Natural disasters
• Individuals with bipolar disorder or schizophrenia
• Individuals with medical conditions such as stroke, tumor, or infections involving the brain 
• A traumatic or stressful event
• Chronic drug or alcohol abuse
• Exposure to toxic chemicals such as organic solvents, mercury, and carbon monoxide

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Amnestic Disorder? (Etiology)

Amnestic Disorders are caused by damage to a part of the brain associated with memory (usually the limbic system). The severity of the disorder is typically determined by the location and amount of area damaged. The different types of Amnestic Disorders have different possible causes linked to them as well.

Amnestic Disorder due to a general medical condition includes: 

• Physical injury to brain due to head trauma
• Psychological trauma or stress: This can cause “dissociative amnesia”
  • Characterized by gaps in memory
  • Triggered by events such as war, genocide, accidents, rape, physical or sexual abuse, and natural disasters
• Brain stroke
• Hydrocephalus
• Infection in the brain such as Lyme disease, HIV infection or AIDS, etc.
• Tumors in the brain, and damage to brain tissue as a result of treatment for tumors (such as radiation therapy or chemotherapy)
• Damage to blood vessels causing ischemia of the brain (condition where blood being carried to brain does not have sufficient oxygen) 
• Brain surgery
• Interrupted oxygen supply to the brain
• Vitamin B1 deficiency disorder: Wernicke-Korsakoff syndrome is a unique type of amnesia and a combination of two separate conditions
  • Wernicke encephalopathy, which is an acute neurological disorder caused by vitamin B1 (thiamin) deficiency 
  • Korsakoff syndrome that develops as a result of untreated Wernicke encephalopathy
• Thyroid hormone deficiency
• Amnestic Disorder caused by psychological disorders that include:
  • Depression
  • Schizophrenia
  • Bipolar disorder

Substance-induced Amnestic Disorder: 

• Chronic heavy drug use
• Exposure to toxins such as lead, mercury, and carbon monoxide 
• Alcoholism: Vitamin B12 deficiency in alcoholism is thought to be the cause of this type of memory loss

Other causes of Amnestic Disorder may include:

• Overuse of certain medications such as barbiturates
• Conditions, such as Parkinson’s disease and multiple sclerosis, causing damage to brain tissue
• Poorly-controlled epilepsy

The causes of transient global amnesia and Amnestic Disorder, NOS are unknown.

What are the Signs and Symptoms of Amnestic Disorder?

The signs and symptoms of Amnestic Disorder may include:

• Difficulties with information recall
• Short-term memory loss
• Disorientation with respect to time and space
• Lack of perspective on their loss of memory; many individuals may deny that there is a problem
• No apparent emotional reaction to their condition, once it is accepted
• Personality changes may be noted
• Confabulation: This is common in those with transient global amnesia, where memory gaps are filled with information that is believed to be true, although in reality, are false
• Confusion/bewilderment

How is Amnestic Disorder Diagnosed?

Individuals with Amnestic Disorders are usually brought in by a close friend or family member to be evaluated, because of the affected individual’s lack of insight on his/her own mental state.

The criteria for diagnosing an Amnestic Disorder include:

• The inability to remember previously known information/events and to learn new information/events
• The memory dysfunction is severe enough to affect one’s daily functioning
• A drastic decline from previous level of memory capabilities is noted. The memory problems are not occurring only during delirium, dementia, substance use or withdrawal

The following methods may be employed for an accurate diagnosis of Amnestic Disorder:

• A thorough physical examination
• Evaluation of signs or symptoms of a traumatic head injury, substance abuse, or a general medical condition 
• Imaging studies of the brain to observe specific areas of brain for any injury, using the following tools:
  • Magnetic resonance imaging (MRI) scan
  • Computed tomography (CT) scan
  • Magnetoencephalography
  • Electroencephalography (EEG)
  • Cerebral angiography
• Blood tests for assessing the following:
  • Vitamin B1 and B12 deficiency
  • Thyroid hormone insufficiency
  • Exposure to environmental toxins
  • Alcohol abuse
  • Drug abuse
  • Infections
• Urine tests to check for the following:
  • Infections
  • Exposure to environmental toxins
  • Consumption of alcohol and drugs
• Testing of cerebrospinal fluid (CSF) for infections: The CSF is obtained through a procedure known as lumbar puncture
• Mini-mental state examination (MMSE) and digit test, to test an individual’s cognitive status. An individual may have to be tested multiple times to ensure consistency and affirm that he/she is not fabricating answers
• Tests to rule out conditions such as Alzheimer’s disease, dementia and delirium

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Amnestic Disorder?

The following are some potential complications associated with Amnestic Disorder:

• Inability to care for oneself
• Inability to hold a job
• Impaired inter-personal relationships
• Problems with social life
• Complications that may arise from the underlying condition, if any

How is Amnestic Disorder Treated?

No treatments have been really proved to be effective in most cases of Amnestic Disorders. However, the following treatment methods may help in arresting its progression and preventing further damage. Nevertheless, in most cases, the treatment may not be possible to recover all of an individual’s lost memory.

• Use of memory strength techniques
• Therapy to use retained memories as a tool to form new ones
• Techniques such as mental organization
• Smartphones to remind an individual of various things and "notepads" to write down their thoughts and appointments
• Using pictures as a reference for memory recall
• Use of vitamin B1 (thiamin) and B12 supplements, specifically for those diagnosed with alcohol-induced memory loss 
• Medication to treat thyroid disorders, control epileptic attacks, etc.
• Medication and psychotherapy for depression
• Medication for schizophrenia, bipolar disorder, and other such psychological disorders
• Psychotherapy involving the following to help an individual retrieve and come to terms with painful/traumatic events, such as in the case of dissociative Amnestic Disorder
  • Hypnosis
  • Drug-facilitated interviews

Individuals with transient global amnesia generally recover without the need for any treatment.

How can Amnestic Disorder be Prevented?

The following tips may help prevent Amnestic Disorders:

• Wearing protective headgear when engaging in activities and sports that may potentially lead to a head injury
• Avoiding contact with environmental toxins by using protective apparatus
• Avoiding alcohol and substance abuse

What is the Prognosis of Amnestic Disorder? (Outcomes/Resolutions)

The prognosis of Amnestic Disorder depends on the cause of the condition.

• Individuals with Amnestic Disorder due to a head injury usually show a good recovery of long-term memory over time. However, the events right before or during the accident are typically never fully regained
• Amnestic Disorders caused by alcoholism do not usually improve significantly over time. Medication can improve memory functioning to some extent; however, the disorder may never be fully cured 
• Recovery from drugs and other substances induced Amnestic Disorder varies from one individual to another; a full recovery may be possible, in some cases
• In many, transient global amnesia usually resolves completely

Additional and Relevant Useful Information for Amnestic Disorder:

Contrary to the characters depicted in movies and television serials, generally, individuals with Amnestic Disorder are aware of their own identity.