Disorder of memory

Memory impairment or memory loss may be defined as a lack of a person’s ability to consistently recollect information to the extent of impairing the daily activities of the person. It can be acute or progressive and chronic. While acute or sudden memory loss can many times be self-limiting or naturally reversed; Progressive and chronic type of memory impairment causes permanent damage to the brain and is usually difficult to be reversed.

CAUSES OF MEMORY IMPAIRMENT :

Acute or sudden memory loss is usually caused by brain trauma, stroke, or as a side effect of medications like statin drugs and chemotherapy, brain infections, brain surgery, or Electroconvulsive Therapy. Acute memory impairment is, however, not as prevalent as progressive and chronic memory loss. Most progressive memory impairments are permanent and may be caused by various underlying factors including:

  • Long standing diseases like meningitis or epilepsy.
  • Abuse of psychedelic drugs,
  • Certain forms of mental illnesses,
  • Certain types of brain tumours or cancers,
  • As a symptom of diseases such as Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease,
  • Pregnancy can at times cause transient mild memory impairment.

TYPES OF MEMORING IMPAIRMENT :

AMNESIA :

Amnesia is defined as a partial or total inability to recall past experiences and events and its origin may be organic or psychogenic. Failure to recall occur DUE TO :

  • Normal memory decay
  • Interference from related material (retroactive{new-old},proactive{old-new}).

PSYCHOGENIC AMNESIA :

Dissociative or hysterical amnesia is the sudden amnesia that occurs during periods of extreme trauma and can last for hours or even days. Associated fugue or wandering state in which the subject travels to another town or country. Katathymic amnesia/motivated forgetting is the inability to recall specific painful memories(occur due to defence mechanism of repression).

  • Absence of personal identity such as name, address and history
  • Absence of personal events
  • The ability to perform complex behaviours is maintained.
  • The person behaves appropriately to their background and education.

ORGANIC AMNESIA :

Acute brain disease: In this condition memory is poor owing to disorders of perception and attention. In acute head injury, there is amnesia, known as retrograde amnesia, that embraces the events just before the injury. This period is no longer than a few minutes but occasionally may be longer, especially in subacute conditions. Anterograde amnesia is amnesia for events occurring after the injury. Blackouts are circumscribed periods of anterograde amnesia experienced particularly by those who are alcohol dependent during and following bouts of drinking.

Subacute course brain disease: The characteristic memory disorder is the amnestic state in which the patient is unable to register new memories. This diagnosis is not made when there are other signs of cognitive impairment as in dementia or when consciousness is clouded as in delirium. Korsakoff’s syndrome is the amnestic syndrome caused by thiamine deficiency, but other causes include cerebrovascular disease, multiple sclerosis, transient global amnesia, head injury and electroconvulsive treatment (ECT).

Chronic coarse brain disease: Patients with amnesia or those with korsakoff’s syndrome usually have a loss of memory extending back into the recent past for a year or so. Patients with a progressive chronic brain disease have amnesia extending over many years, though the memory for recent events is lost before that for remote events. This was pointed by Ribot and is known as Ribot’s law memory regression.

OTHER AMNESIAS :

Anxiety amnesia occurs when there is anxious preoccupation or poor concentration in disorders such as depressive illness or generalized anxiety. More severe forms of amnesia in depressive disorders resemble dementia and are known as depressive pseudodementia. Amnesia’s in anxiety and depressive disorders are generally caused by impaired concentration and resolve once the underlying disorder is treated.

PARAMNESIA :

Falsification of memory by distortion can be conveniently divided into:

  1. Distortions of recall and
  2. Distortions of recognition.

This can occur in normal subjects:

  • Due to the process of normal forgetting or
  • Due to proactive and retroactive interference from newly acquired material,
  • With emotional problems,
  • In organic states.

Retrospective falsification:

Retrospective falsification refers to the unintentional distortion of memory that occurs when it is filtered through a person’s current emotional, experiential and cognitive state. Depressive illness who describe all past experiences in negative terms due to the impact of their current mood. •A depressed person will highlight their failures while ignoring and/or forgetting about their success.

False memory:

False memory is the recollection of an event that did not occur but which the individual subsequently strongly believes did take place(Brandon et al, 1998). The syndrome refers not to distortion of true memories, as in normal forgetting, but to the actual construction of memories around events that never took place. E.g., False confessions to serious crime.

Screen memory :

A screen memory is a recollection that is partially true and partially false; it is thought that the individual only recalls part of the true memory because the entirety of the true memory is too painful to recall. For example, an individual may recall that childhood sexual abuse was perpetrated by a neighbor because it is too painful to recall that the abuse was, in fact, perpetrated by their own brother.

Confabulation :

Confabulation is the falsification of memory occurring in clear consciousness in association with organic pathology. It manifests itself as the filling-in of gaps in memory by imagined or untrue experiences that have no basis in fact. The confabulation diminishes as the impairment worsens.

Pseudologia fantastica :

Pseudologia fantastica or fluent plausible lying (pathological lying) is the term used, by convention, to describe the confabulation that occurs in those without organic brain pathology such as personality disorder of antisocial or hysterical type. People who falsify or exaggerate the past in order to impress others.

Munchausen’s Syndrome :

Munchausen’s syndrome is a variant of pathological lying in which the individual presents to hospitals with bogus illnesses, complex medical histories, and often multiple surgical scars. A proxy form of this condition has been described in which the individual, usually a parent, produces a factitious illness in somebody else, generally their child.

Vorbeireden/ approximate answers

This suggests that the patient understands the question but appears to be deliberately avoiding the correct answers. For e.g., When asked how many eyes does the dog has, the answer given is 3.

Cryptomnesia

 Cryptomnesia is described by Sims (1997) as ‘the experience of not remembering that one is remembering’. For e.g., a person writes a witty passage and does not realize that they are quoting from some passage they have seen elsewhere rather than writing something original.

Retrospective Delusion:;

Retrospective delusions are found in some patients with psychoses who backdate their delusions in spite of the clear evidence that the illness is of recent origin. Thus, the person will say that they have always been persecuted or that they have always been evil. Primary delusional experiences may take the form of memories and these are known as delusional memories, consisting of sudden delusional ideas and delusional perceptions.

DISTORTION OF RECOGNITION :

Déjà vu is not strictly a disturbance of memory, but a problem with the familiarity of places and events. It comprises the feeling of having experienced a current event in the past, although it has no basis in fact. jamais vous is the knowledge that an event has been experienced before but is not presently associated with the appropriate feelings of familiarity. Déjà entendu, the feeling of auditory recognition, and déjà pense, a new thought recognized as having previously occurred, are related to déjà vu, being different only in the modality of experience. These can be experienced by normal subjects as well as among those with temporal lobe epilepsy.

False reconnaissance is defined as false recognition or misidentification and it can occur in organic psychoses and in acute and chronic schizophrenia. It may be positive when the patient recognizes strangers as their friends and relatives. In confusional states and acute schizophrenia, at most, a few people are positively misidentified.

In negative misidentification, the patient insists that friends and relatives are not who they say they are and that they are strangers in disguise. Some patients assert that some or all people are doubles of the real people whom they claim to be. This is known as Capgras syndrome and occurs in schizophrenia and in dementia

Hyperamnesia:

The opposite of amnesia and paramnesia can also occur and is termed hypermnesia, or exaggerated registration, retention, and recall.

Flashbulb memories are those memories that are associated with intense emotion. They are unusually vivid, detailed, and long-lasting. For e.g., many people can recall where and what they were doing when they heard of some news.

Flashbacks are sudden intrusive memories that are associated with the cognitive and emotional experiences of a traumatic event such as an accident. It may lead to acting and/or feeling that the event is recurring and attempts have been made to use this as a defense in some murder trials. It is regarded as one of the characteristic symptoms of post-traumatic stress disorder but is also associated with substance misuse disorders and emotional events.

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