MODULE 13: NEUROCOGNITIVE DISORDERS
Module Overview
Module 13 covers the different neurocognitive disorders including their
clinical presentation, epidemiology, and etiology. The discussion focuses
on Delirium, Major Neurocognitive Disorder, and Mild Neurocognitive
Disorder.
Module Outline
13.1. Clinical Presentation
13.2. Epidemiology
13.3. Etiology
Module Learning Outcomes
Describe the clinical presentations of neurocognitive disorders.
Describe the epidemiology and etiology of neurocognitive disorders.
13.1. Clinical Presentation
Section Learning Objectives
Describe the clinical presentations of Delirium, Major Neurocognitive
Disorder, and Mild Neurocognitive.
Unlike many of the disorders discussed, neurocognitive disorders often
result from disease processes or medical conditions. Therefore, it is
important that individuals presenting with these symptoms complete a
medical assessment to better determine the etiology behind the disorder.
There are three main categories of neurocognitive disorders- Delirium,
Major Neurocognitive Disorder, and Mild Neurocognitive Disorder.
Within major and minor neurocognitive disorders are several subtypes
due to the etiology of the disorder.
13.1.1. Delirium
Delirium is characterized by a significant disturbance in attention or
awareness and cognitive performance that is significantly altered from
one’s usual behavior. Disturbances in attention are often manifested as
difficultly to sustain, shift, or focus attention. Additionally, an individual
will also have a disruption in cognition, including confusion of where they
are. Disorganized thinking, incoherent speech, and hallucinations and
delusions may also be observed. Onset of delirium is abrupt, occurring
over a period of several hours. Symptoms can range from mild to severe,
and can last from days to several months.
13.1.2. Major Neurocognitive Disorder
Individuals with major neurocognitive disorder show significant decline
in both overall cognitive functioning as well as the ability to
independently meet the demands of daily living such as paying bills,
taking medications, or caring for oneself.
Within the umbrella of major neurocognitive disorder is dementia, a
major decline in cognition and self-help skills due to a neurocognitive
disorder. The DSM-V refrained from using this term in diagnostic
categories as it is often used to describe the natural decline in
degenerative dementias that affect older adults; whereas neurocognitive
disorder is the preferred term used to describe conditions affecting
younger individuals such as impairment due to traumatic brain injuries
or other medical conditions. Therefore, while dementia is accurate in
describing those experiencing major neurocognitive disorder due to age,
it is not reflective of those experiencing neurocognitive issues secondary
to an injury or illness.
13.1.3. Mild Neurocognitive Disorder
Individuals with mild neurocognitive disorder demonstrate
a modest decline in one of the cognitive areas. The decline in functioning
is not as extensive as that seen in major neurocognitive disorder and the
individual does not experience difficulty independently engaging in daily
activities; however, they may require assistance or extra time to
complete these tasks, particularly if the cognitive decline continues to
progress.
It should be noted that the primary difference between major and mild
neurocognitive disorder is the severity of the decline and independent
functioning. Individuals can go from major to mild neurocognitive
disorders following recovery from a stroke or traumatic brain injury.
13.2. Epidemiology
Section Learning Objectives
Describe the epidemiology of neurocognitive disorders.
Delirium often occurs among those hospitalized for other medical issues
and in older individuals. While the rate of occurrence is quite rare among
the general public, it significantly increases among individuals older than
85 years old.
Major and mild neurocognitive disorder prevalence rates vary widely
depending on the etiological nature of the disorder. Dementia occurs in
1-2% of individuals age 65 years old and up to 30% of individuals over
age 85.
Alzheimer’s disease, the most commonly diagnosed neurocognitive
disorder, is where 60-90% of dementias is attributable.
13.3. Etiology
Section Learning Objectives
Describe the causes and symptoms of the different subtypes of
Neurocognitive disorders.
Neurocognitive disorders occur due to a wide variety of medical
conditions or injury to the brain. Majority of these neurocognitive
disorders are both degenerative, meaning the symptoms and cognitive
deficits become worse overtime, as well as related to a medical condition
or disease.
In order to specify the type of neurocognitive disorder, additional
diagnostic criteria needs to be met specific to one of the following
subtypes.
Alzheimer’s Disease
Alzheimer’s disease is the most prevalent neurodegerative disorder.
While the primary symptom of Alzheimer’s disease is the gradual
progression of impairment in cognition, there is also an identifiable
concrete evidence of cognitive decline.
Two abnormal brain structures— beta-amyloid
plaques and neurofibrillary tangles—both of which are responsible for
neuron death, inflammation, and loss of cellular connections, are
implicated for the disease. Neurons shrinking or dying within the
hypothalamus, thalamus, and the locus ceruleus have been linked to
declining cognition.
Environmental toxins such as high levels of zinc and lead may also
contribute to the development of Alzheimer’s disease.
Alzheimer’s disease is defined by the onset of symptoms. Early-
onset Alzheimer’s disease occurs before the age of 65. Late-
onset Alzheimer’s disease occurs after the age of 65 and has less of a
familial influence.
Traumatic Brain Injury (TBI)
TBIs occur when an individual experiences a significant trauma or injury
to the head. Neurocognitive disorder due to TBI is diagnosed when
persistent cognitive impairment is observed immediately following the
head injury, along with one or more of the following symptoms: loss of
consciousness, posttraumatic amnesia, disorientation and confusion, or
neurological impairment.
The most common type of TBI is a concussion. A concussion occurs
when there is a significant blow to the head, followed by changes in brain
functioning. It often causes immediate disorientation or loss of
consciousness, along with headaches, dizziness, nausea, and sensitivity
to light. While symptoms of a concussion are usually temporary, there
can be more permanent damage due to repeated concussions,
particularly if they are within close time periods.
Vascular Disorders
Neurocognitive disorders due to vascular disorders can occur from a one-
time event such as a stroke, or from ongoing subtle disruptions of blood
flow within the brain. There are two types of strokes—a hemorrhagic
stroke which occurs when a blood vessel bursts within the brain, and
an ischemic stroke which is when a blood clot blocks the blood flow in
an artery within the brain.
Substance Abuse
Significant cognitive changes occur due to repetitive drug and alcohol
abuse. Delirium can be observed in individuals with extreme substance
intoxication, withdrawal, or even when multiple substances have been
used within a close time period. While delirium symptoms are often
transient during these states, mild neurocognitive impairment due to
heavy substance abuse may remain until a significant period of
abstinence is observed.
Dementia with Lewy Bodies
Symptoms associated with neurocognitive disorder due to Lewy bodies
include significant fluctuations in attention and alertness; recurrent
visual hallucinations; impaired mobility; and sleep disturbance. Lewy
bodies are irregular brain cells that result from buildup of abnormal
proteins in the nuclei of neurons.
Frontotemporal Lobar Degeneration (FTLD)
FTLD causes progressive declines in language or behavior due to the
degeneration in the frontal and temporal lobes of the brain. Symptoms of
FTLD include significant changes in behavior and/or language.
Individuals may present with apathy or disinhibition. Additionally, they
may lose interest in socialization as they often lose empathy and
sympathy for others.
Parkinson’s Disease
Parkinson’s disease is the 2nd most common neurodegenerative disorder
in the United States. Aside from the tremors of hands, arms, legs, or face
as the most common symptom, the symptoms of rigidity of the limbs and
trunk; slowness in initiating movement; and drooping posture or
impaired balance and coordination, are the other three main symptoms
of the disease.
Huntington’s Disease
Huntington’s disease is a rare, genetic disorder in which involves
involuntary movement, progressive dementia, and emotional instability.
Due to the degenerative nature of the disorder, there is a shortened life-
expectancy as death typically occurs 15-20 years post onset of symptoms.
Although symptoms can present at any time, the average age of symptom
presentation is during middle adulthood. As symptoms progress, more
physical symptoms present such as facial grimaces, difficulty speaking,
and repetitive movements.
HIV Infection
Cognitive impairment is sometimes the first symptom of untreated HIV.
While symptoms vary among individuals, slower mental processing,
difficulty with complex tasks, and difficulty concentrating/learning new
information are among the most common early signs.
