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What mental illness makes you forget?

Forgetting things occasionally is normal, but consistent forgetfulness or memory loss can be a symptom of certain mental illnesses. There are a few key mental health conditions that list significant memory problems as a primary symptom.

Alzheimer’s Disease

Alzheimer’s disease is a progressive neurological disorder that destroys memory and other important mental functions. It is the most common cause of dementia. Early symptoms include difficulty remembering recent events or conversations. As the disease advances, memory loss worsens and patients may forget details about themselves or their family and have difficulty with everyday tasks.

In Alzheimer’s disease, memory loss occurs because of damage to brain cells. Abnormal protein deposits form plaques and tangles that destroy connections between nerve cells in parts of the brain involved in memory. There is also loss of tissue mass as nerve cells shrink and die.

Memory loss typically begins with forgetting recent information. For example, a person may repeat themselves often in conversation, forget events that just took place, or struggle to remember appointments. Over time, memory loss becomes more severe and begins to affect long-term memories as well. Advanced Alzheimer’s can involve forgetting details about one’s personal history or inability to recognize loved ones.

Short-term memory refers to information that is actively held in the mind for immediate use, while long-term memory refers to information stored over a long period. Alzheimer’s typically impacts short-term memory in the earlier stages, while long-term memory remains intact longer. However, as Alzheimer’s advances, long-term autobiographical memory fails as well.

Key Facts About Alzheimer’s:

  • Progressive neurological disorder characterized by memory loss and cognitive decline
  • Most common cause of dementia in older adults
  • Memory loss begins with forgetfulness about recent events/conversations
  • Over time, destroys ability to retain new information and access long-term memories
  • Involves damage to brain cells from abnormal protein deposits and tissue loss

Korsakoff’s Syndrome

Korsakoff’s syndrome is a chronic memory disorder caused by severe deficiency of thiamine (vitamin B1). Most cases occur in people with alcoholism. It is closely related to Wernicke-Korsakoff syndrome, which involves acute brain damage from severe thiamine deficiency.

The memory impairment in Korsakoff’s syndrome primarily affects episodic memory, impacting the ability to learn new information. Patients have difficulty remembering events that occurred after the brain damage began. They are unable to recall experiences from minutes or hours earlier, resulting in a loss of continuous memory.

Korsakoff’s syndrome also causes something called confabulation. This involves making up information to fill in memory gaps without realizing it. For example, someone may describe details about what they did yesterday that are clearly fabricated but believed to be true.

While episodic memory is impaired, other memory systems are often unaffected in Korsakoff’s syndrome. Procedural memory (how to do things), semantic memory (facts), and working memory (temporary storage) typically remain intact. Patients can often still remember skills, learned behaviors, and long-term personal information from before the disorder began.

Key Facts About Korsakoff’s Syndrome:

  • Caused by thiamine deficiency, usually related to chronic alcoholism
  • Primarily impacts episodic memory – inability to form new memories
  • Patients have difficulty recalling recent events and experiences
  • Involves confabulation (making up details to fill in memory gaps)
  • Long-term memories from before disease onset usually remain

Transient Global Amnesia

Transient global amnesia consists of a sudden temporary episode of memory loss and confusion. It typically lasts for several hours before normal memory function returns. The cause is not clearly known but may involve transient reduced blood flow in parts of the brain related to memory.

During an episode of transient global amnesia, a person retains awareness of self and identity but cannot recall recent experiences or form new memories. They may repetitively ask questions because they do not remember the answer given minutes earlier. The amnesia resolves fairly rapidly and patients have no permanent memory deficits afterwards.

Transient global amnesia primarily impacts anterograde amnesia – the inability to form new memories following the onset of amnesia. It does not usually cause loss of past memories, which is known as retrograde amnesia. However, patients may have trouble recalling events immediately before the episode.

Episodes can last 2-12 hours. Temporary retrograde amnesia for a few minutes before the attack is common. The disorder mainly affects middle-aged and older adults and recurrence is rare. The cause of transient global amnesia is unclear but is often preceded by strenuous activity and may result from temporary decreased blood flow to parts of the brain involved in memory.

Key Facts About Transient Global Amnesia:

  • Sudden short-term episode of memory loss and confusion
  • Lasts 2-12 hours before normal memory function returns
  • Anterograde amnesia – cannot form new memories during episode
  • Minimal impact on past memories
  • Cause thought to involve disrupted blood flow in memory areas of brain

Dissociative Amnesia

Dissociative amnesia is a rare psychiatric disorder characterized by sudden memory loss due to emotional or psychological trauma. It typically involves the inability to recall important personal information that is too traumatic or stressful to remember.

Dissociative amnesia is considered a dissociative disorder. Dissociation refers to mental detachment from thoughts, emotions, memories or sense of self. Dissociative amnesia selectively blocks access to traumatic memories. The amnesia helps the person avoid recalling memories surrounding the event.

Dissociative amnesia can involve:

  • Complete amnesia for childhood
  • Localized amnesia for certain time periods
  • Generalized amnesia for identity and life history

The memory loss is psychologically-based and typically does not involve structural damage to the brain. During dissociative amnesia, forgotten memories may still influence thoughts and behaviors. however, the person remains unable to recall the memories at will. They may later recover lost memories spontaneously or through psychotherapy techniques.

Key Facts About Dissociative Amnesia:

  • Rare psychiatric disorder characterized by sudden memory loss due to trauma
  • Involves detachment from stressful or traumatic memories
  • Memory blocked is too stressful or disturbing to recall
  • No structural brain damage, psychological basis
  • Memories may recover later spontaneously or with therapy

Post-Traumatic Amnesia

Post-traumatic amnesia refers to memory loss that occurs immediately following a traumatic brain injury or TBI. It may last from minutes to weeks before full memory function returns. The length of post-traumatic amnesia is related to the severity of the brain injury.

Post-traumatic amnesia involves:

  • Confusion and disorientation immediately after the injury
  • Anterograde amnesia – inability to form new memories
  • Retrograde amnesia – impaired recall of events before injury

As the post-traumatic amnesia subsides, memory gradually improves, often in reverse order. Recent memories return first, followed by more distant memories. However, there may be permanent gaps in memory especially surrounding the injury event.

The hippocampus and surrounding structures are especially vulnerable to trauma. Since this area of the brain is crucial for encoding new memories, damage can cause anterograde amnesia after a TBI. With mild injuries, amnesia may only last minutes. Severe trauma can cause weeks of memory loss with gradual recovery.

Key Facts About Post-Traumatic Amnesia:

  • Memory loss occurs after traumatic brain injury (TBI)
  • Involves confusion, disorientation, anterograde and retrograde amnesia
  • Lasts minutes to weeks depending on TBI severity
  • Memory typically returns gradually in reverse order
  • May have permanent gaps in memory around the injury event

Comparison of Memory Loss in Mental Illness

The table below summarizes some of the key differences in memory loss associated with different mental health conditions:

Disorder Memory Loss Patterns Duration Cause
Alzheimer’s Disease Progressive memory loss begins with short-term memory deficits. Long-term memory increasingly affected over time. Permanent, worsens over years Brain cell damage from plaques and tangles
Korsakoff’s Syndrome Mainly affects episodic memory. Anterograde amnesia prevents forming new memories. Retrograde amnesia limited. Chronic but stable Thiamine deficiency from malnutrition
Transient Global Amnesia Temporary anterograde amnesia. Minimal retrograde amnesia. Lasts 2-12 hours Disrupted blood flow to memory centers
Dissociative Amnesia Blocks access to traumatic memories. Localized or selective memory loss. May recover over time Psychological defense mechanism
Post-Traumatic Amnesia Anterograde and retrograde amnesia after head injury. Gradual recovery typically in reverse order. Lasts minutes to weeks Traumatic brain injury


Memory loss can occur temporarily or permanently as a result of certain mental illnesses and conditions. Alzheimer’s disease progressively impairs all memory types. Korsakoff’s syndrome mainly damages short-term memory creation. Dissociative and post-traumatic amnesia block access to traumatic memories. Transient global amnesia causes brief disruption of new memory formation.

The pattern, duration, and cause of memory loss differ depending on the specific disorder. Identification of memory deficits and other associated symptoms can help distinguish between different diagnoses. Early evaluation of significant persistent memory loss is important to determine the underlying cause and guide appropriate treatment.