Cognitive Disorders

Cognitive Disorders (part 1)Amnesia and Delirium

Sami Adil
15th Nov. 2015

Amnestic Disorders

impairment in the ability to create new memories. Three variations of the amnestic disorder diagnosis, differing in etiology, are offered: amnestic disorder caused by a general medical condition (e.g., head trauma), substance-induced persisting amnestic disorder (e.g., caused by carbon monoxide poisoning or chronic alcohol consumption), and amnestic disorder not otherwise specified for cases in which the etiology is unclear.

The two modifiers are (1) transient, for duration less than 1 month, and (2) chronic, for conditions extending beyond 1 month.

Epidemiology

No adequate studies
Alcohol disorders
Head injury

Etiology

Thalamus (dorsomedial and midline nuclei)
Hippocampus, the mamillary bodies, and the amygdala
Other areas
Unilateral Vs. Bilateral
Left Vs. Right


Major causes of amnesia
General Medical: hypoglycemia, seizures, head trauma, CVA, MS, and others
Substance-related: alcohol, BNZ, neurotoxins,

Diagnosis

For the diagnosis of amnestic disorder, the (DSM-IV-TR) requires the development of memory impairment as manifested by impairment in the ability to learn new information or the inability to recall previously learned information,‌ and the memory disturbance [must cause] significant impairment in social or occupational functioning.

Clinical Features and Subtypes

The central symptoms are (anterograde amnesia) & (retrograde amnesia).

Time of trauma Vs time of amnesia

Short term Vs. Long term Vs. immediate

With improvement, patients may experience a gradual shrinking of the time for which memory has been lost, although some patients experience a gradual improvement in memory for the entire period.

The onset of symptoms can be sudden, as in trauma, cerebrovascular events, and neurotoxic chemical assaults, or gradual, as in nutritional deficiency and cerebral tumors. The amnesia can be of short duration (specified by DSM-IV-TR as transient if lasting 1 month or less) or of long duration (specified by DSM-IV-TR as persistent if lasting more than 1 month).

Patients may attempt to cover their confusion with confabulatory answers to questions. Characteristically, patients with amnestic disorders do not have good insight into their neuropsychiatric conditions.


Differential Diagnosis
Dementia and Delirium
Amnestic disorders can be distinguished from delirium, because they occur in the absence of a disturbance of consciousness and are striking for the relative preservation of other cognitive domains.

Characteristic

Dementia
Amnestic Disorder
Onset
Insidious
Can be abrupt
Course
Progressive deterioration
Static or improvement
Language
Impaired
Intact
Praxis or function
Impaired
Intact


Normal Aging
Some minor impairment in memory may accompany normal aging, but the DSM-IV-TR requirement that the memory impairment cause significant impairment in social or occupational functioning should exclude normal aging from the diagnosis.

Dissociative Disorders

The dissociative disorders can sometimes be difficult to differentiate from the amnestic disorders. Patients with dissociative disorders, however, are more likely to have lost their orientation to self and may have more selective memory deficits than do patients with amnestic disorders. For example, patients with dissociative disorders may not know their names or home addresses, but they are still able to learn new information and remember selected past memories. Dissociative disorders are also often associated with emotionally stressful life events involving money, the legal system, or troubled relationships.

Factitious Disorders

Patients with factitious disorders who are mimicking an amnestic disorder often have inconsistent results on memory tests and have no evidence of an identifiable cause. These findings, coupled with evidence of primary or secondary gain for a patient, should suggest a factitious disorder.

Course and Prognosis

Depends on etiology
Acute and reversible
Chronic and static

Treatment

The primary approach to treating amnestic disorders is to treat the underlying cause. Although a patient is amnestic, supportive prompts about the date, the time, and the patient's location can be helpful and can reduce the patient's anxiety.
Denial

DELIRIUM

Delirium is defined by the acute onset of fluctuating cognitive impairment and a disturbance of consciousness.
Delirium is underrecognized by health care workers.

Epidemiology

30 % of inpatients
Undiagnosed
Poor prognostic sign

Etiology

Criteria: Medical FRAT

• Medical cause
• Fluctuating
• Recent onset
• Attention
• Thinking (orientation and perception)
• Delusions

Delusions can occur (paranoid)

DDx
Dementia
Depression
schizophrenia
Fluctuating course


Treatment
Treat the cause
Environmental
Haloperidol and lorazepam
DT
Eye patch