Amnesia is a pathological loss of memories of current or past life circumstances. It is included in the symptoms of neurological diseases, mental disorders, acute poisoning, chronic intoxication. The diagnostic process takes into account clinical data, the results of neurological and mental examination, EEG, MRI, CT, blood test, analysis of cerebrospinal fluid. Treatment is carried out in accordance with causal pathology, the main methods are psycho- and pharmacotherapy. In the presence of tumors, hematomas, their surgical removal is carried out.
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Amnesia in Latin means unconsciousness. The absence of memories is not always a pathological condition. There is childhood amnesia – most people do not remember the events of the first 2-3 years of life. In the medical aspect, amnesia is considered as the loss of previously existing memories of significant life events, the inability to recall recent circumstances. Amnesic syndrome in combination with other symptoms is an integral part of the clinic of various neurological and psychiatric diseases. According to some estimates, about 25% of the world’s population suffers from memory disorders. Along with amnesia, such disorders include qualitative mnestic disorders characterized by a weakening of the ability to remember, difficulty remembering.
The etiofactors of amnesic syndrome are numerous and diverse. In old age, vascular disorders and degenerative processes play a leading role in the etiology. Traumatic and psychological factors prevail in young patients. All causes of memory loss can be divided into two large groups: organic and psychological.
Organic causes lead to metabolic, morphological or bioelectric changes in cerebral structures:
- Traumatic brain injury (severe concussion, brain injury). Amnesia of events preceding the trauma is typical, which may be temporary.
- Brain tumors. The loss of memories is caused by compression and death of neurons.
- Cerebral hypoxia provokes a violation of interneuronal connections, the death of nerve cells. It is observed in disorders of cerebral circulation (stroke, TIA), asphyxia, carbon monoxide poisoning, large blood loss, respiratory failure.
- Neuroinfections (neuroSPID, tick-borne encephalitis, purulent meningitis) can occur with amnesia due to damage to cerebral tissues by infectious agents and inflammatory mediators.
- Intoxication. Amnesia occurs as a result of toxic brain damage. It is observed in alcoholism, drug addiction, drug overdose, poisoning with solvents, pesticides.
- Degenerative diseases of the central nervous system (Alzheimer’s disease, vascular dementia, Pick’s disease). The loss of mnestic functions is caused by demyelination, gliosis, and atrophy of brain tissues.
- Epilepsy. Memory loss extends to the period of the attack, is associated with loss of consciousness.
- Migraine. Amnesic symptoms are provoked by a disorder of cerebral hemodynamics that occurs during migraine paroxysm.
Psychological causes affect only the human psyche, do not have a pathological effect on the brain:
- Psychological trauma (accident, death of a loved one, rape, abduction, terrorist attack, military actions). Amnesia concerns psychotraumatic events, is formed as a defensive reaction.
- Mental disorders. Memory loss is episodic. It can be noted in schizophrenia, dissociative disorder, hysteria. Partial amnesia is observed after delirium.
The exact mechanism of amnesia development is unknown. It is believed that the function of storing and reproducing information is carried by cerebral neurons. The basis of mnestic disorders of organic genesis is the destruction of interneuronal messages, dysfunction of neurons. There may be a complete loss of information available in the brain due to the death of the structural elements that store it. Psychogenic amnesia has a different mechanism of formation. In the literature on neurology and psychiatry, the authors explain it as a loss of the ability to restore certain information in memory. Typical is the selective loss from memory of a separate group of interrelated events that have a subjective inner meaning for the patient.
Amnesia is classified taking into account the etiology, volume, time characteristics of lost memories, and the development of disorders that have arisen. According to the completeness of memory loss , it happens:
- Complete – absolute loss of memories for a certain period of the past.
- Partial – there are vague images, fragments of memories.
- Local – selective amnesia of a particular skill. It is characteristic of psychogenic memory disorders.
Depending on the time of the forgotten events in relation to the time of memory problems , there are the following types of amnesia:
- Retrograde – lack of memory for events that took place before the onset of the disorder.
- Anterograde – disturbed memories of the circumstances that occurred after the onset of the disease.
- Anteroretrograde is a combination of the first two forms.
- Fixation – loss of memory for what is happening at the moment. It can last for several minutes.
According to the type of flow , the following options are distinguished:
- Regressing – gradually there is a recovery of memories.
- Stationary – the memory state remains without dynamics.
- Progressive – amnesia worsens, the events of the present and the increasingly distant past are erased from memory.
The basic symptom is the inability to recall the circumstances that occurred. The loss of memories concerns a certain time interval in the patient’s life. The sequence is described by Ribot’s law: first, what happened recently is forgotten, then the facts of the immediate past, then more recent events. Memory recovery occurs in reverse order. Sometimes confabulations are noted – fictional memories with which the patient tries to fill the gaps in his memory. An amnesic symptom complex is observed in combination with other manifestations characteristic of the underlying disease.
Post-stroke amnesia is combined with hypomnesia (a general decrease in memory of the events of the present), paramnesia (confusion of the circumstances of the past and present), speech disorders, motor deficits. Amnesia, which is an integral part of the psycho-organic syndrome, manifests itself against the background of cognitive disorders: a decrease in the ability to assimilate information, a decrease in attentiveness, slowness of thinking. Dissociative memory loss is accompanied by absent-mindedness, possible affective states, vagrancy. Transient global amnesia is characterized by transient episodes up to disorientation of the patient. The combination of different types of amnesia is characteristic of Korsakov syndrome.
Inpatient disorder is hard experienced by patients, provokes the formation of a false sense of guilt, the development of depression. Progressive amnesia leads to disability. Patients forget the way home, are unable to navigate in previously familiar terrain. Acquired knowledge and skills disappear from memory. Subsequently, there is disorientation in time, in one’s own personality. The patient requires constant care.
The diagnostic algorithm is individual, compiled in accordance with the clinical picture of the disease. It is implemented by a consulting neurologist with the involvement, if necessary, of a psychiatrist, a narcologist, an infectious disease specialist, a neurosurgeon. The diagnostic plan includes:
- Anamnesis collection. A thorough inquiry about the events preceding the disease, the manifestations of the disease is carried out with the involvement of the patient’s relatives.
- Assessment of neurological status. It makes it possible to identify signs of organic CNS disease, to determine the degree of post-traumatic changes.
- Assessment of mental status. Comprehensive psychological examination is necessary for patients with psychogenic amnesia, mental disorders.
- Studies of cerebral hemodynamics. They are carried out if the vascular genesis of memory disorders is suspected. The simplest method is rheoencephalography, more informative – ultrasound of the vessels of the head, duplex scanning, MRI of the vessels.
- Visualization of brain structures. CT brain is prescribed to patients with TBI, intracranial hematoma. Cerebral MRI is effective in the diagnosis of tumors, degenerative processes, post-stroke foci.
- Electroencephalography. Performed by patients with symptoms of epilepsy. EEG allows you to diagnose paroxysmal brain activity, determine its nature.
- Blood test. According to the indications, the level of vitamin B1, toxic substances is determined, a drug test is performed.
- Examination of cerebrospinal fluid. It is carried out under the assumption of infectious etiology, intracranial hemorrhage.
Therapy is selected according to the etiology and symptoms of the underlying disease. With organic amnesia, mainly drug treatment is used, with psychogenic – psychotherapeutic. In pharmacotherapy of organic forms are used:
- Vascular agents (vasodilators, antiplatelet agents) – improve cerebral blood flow and tissue nutrition.
- Neuroprotectors and antioxidants – optimize the metabolism of neurons, increase their resistance to hypoxia and adverse effects.
- Anticholinesterase pharmaceuticals – inhibit the progression of dementia in old age, increase daytime activity.
- Memantines – improve mnestic functions. Effective in the treatment of Alzheimer’s disease.
- Nootropics – stimulate cognitive abilities, activate the metabolism of cerebral tissues.
Additionally, psychotherapeutic techniques are used aimed at adapting the patient to the presence of gaps in memories. In some cases, hypnotherapy is used to recall the past. The presence of a cerebral tumor, hematoma, and a site of crushing is an indication for treatment by neurosurgical intervention.
The treatment of psychogenic forms is not aimed at restoring lost memories, but at the patient’s acceptance of the fact of their absence. Therapy is carried out by a psychiatrist, includes:
- Psychotherapy. Through cognitive behavioral therapy, the development of a new attitude to memory problems is achieved. Dissociated amnesia caused by family conflict requires family psychotherapy. In the presence of child psychotrauma, psychoanalysis is used, allowing the patient to reconsider the attitude to what happened.
- Creative treatment. Suitable for patients who are not inclined to show their feelings and thoughts. It is carried out through fairy tale therapy, art therapy, etc.
- Drug therapy. It is necessary as a supplement to psychotherapy in patients with anxiety, depression, restless state, mental disorders. Individual selection of drugs of the following groups is made: antidepressants, sedatives, neuroleptics.
Prognosis and prevention
The course and outcome of pathology are closely related to the etiofactor, the underlying disease, and the age of the patient. Post-traumatic amnesia is usually reversible. Amnesia due to degenerative changes in the central nervous system is characterized by a steadily progressive course. Psychogenic disorder is prone to partial regression as a result of ongoing therapy. At a young age, memory is restored better than in the elderly. Prevention of amnesic syndrome includes the prevention of head injuries, infections, intoxications, traumatic effects, correct and timely treatment of migraines, epilepsy, vascular disorders.