Neurocognitive Disorders

This article provides a general overview of neurocognitive disorders, along with specific information on the causes, symptoms, complications, diagnostic process, and treatment options.

Key Takeaways:

• Neurocognitive disorders involve specific cognitive impairments that make daily life difficult. Severe cases require caregiver assistance.

• Increasing age is one of the biggest risk factors, especially after age 65. However, there are a variety of causes, some of which may affect younger individuals too.

• Many neurocognitive disorders are progressive and untreatable, while some can be reversed partially or fully. Treatment depends on the exact cause, severity, and outlook.

Understanding Neurocognitive Disorders

Neurocognitive disorders are a specific group of mental disorders classified in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). The main shared feature of neurocognitive disorders is acquired cognitive deficits that result in significant declines in functioning compared to previous levels, such as with attention, executive function, memory, and language. These disorders are not present at birth or in very early life, but develop over time due to various causes. ^{[1] [2]}

The prevalence of mild and major neurocognitive disorder increases dramatically with age, especially after age 60. The overall prevalence of major neurocognitive disorder (commonly referred to as dementia) is around 1 to 2%, but reaches up to 30% by age 85. Mild neurocognitive disorder has a prevalence of 2 to 10% at age 65, and 5 to 25% by age 85. ^[2]

Categories of Neurocognitive Disorders

The DSM-5 groups neurocognitive disorders into three main categories: delirium, mild neurocognitive disorder, and major neurocognitive disorder. This represents a change from the DSM-IV, which had four categories (delirium, dementia, amnestic disorders, and other cognitive disorders).

Delirium is characterized by a disturbance in attention, reduced awareness of the environment, and additional disturbances in cognition, such as with memory or perception. Delirium can be acute, lasting hours to days, or persistent, lasting weeks to months. ^[2]

Mild neurocognitive disorder refers to a moderate decline in cognitive functioning. This often requires greater effort or compensation to overcome, but does not interfere with daily living and overall functioning. ^{[1] [2]}

Major neurocognitive disorders are characterized by a significant decline in cognitive functioning and severe cognitive impairment. This leads to significant interference with independent daily living activities and often requires assistance from others to carry out these tasks. ^{[1] [2]}

Major neurocognitive disorder has previously been referred to as dementia, and many people still use this term. However, major neurocognitive disorder is the preferred term, especially in cases of younger adults. It is also a bit broader term than dementia, given that a deficit in only one cognitive domain needs to be present, whereas a dementia diagnosis requires multiple cognitive deficits. We will use major neurocognitive disorder predominantly in this article.

Causes of Neurocognitive Disorders

There are many possible causes of neurocognitive disorders. Understanding the causes of neurodegenerative disorders is particularly important given that the DSM-5 specifically lists subtypes for mild and major neurocognitive disorder based on the cause.

Causes of neurocognitive disorders include: ^{[1] [2] [3]}

Traumatic Brain Injury

• Bleeding into the brain (intracerebral hemorrhage)

• Bleeding into the space around the brain (subarachnoid hemorrhage)

• Blood clot inside the skull but outside of the brain (subdural or epidural hematoma)

Cardiovascular Disorders

• Heart infections, such as myocarditis, endocarditis

• Stroke

• Transient ischemic attack

Degenerative Disorders

• Alzheimer’s disease

• Frontotemporal degeneration

• Lewy body disease

• Prion disease (e.g. Creutzfeldt-Jakob disease)

• Huntington’s disease

• Multiple sclerosis

• Parkinson’s disease

• Pick disease

Breathing Conditions

• Low oxygen in the blood (hypoxia)

• High carbon dioxide level in the body (hypercapnia)

Metabolic Causes

• Kidney disease

• Liver disease

• Hyperthyroidism or hypothyroidism

• Vitamin deficiency (e.g. B1, B12, folate)

Substance/Medication Use

• Drug or alcohol intoxication

• Alcohol withdrawal

• Medicines, such as:

• Corticosteroids

• Sedative-hypnotics

• Antidepressants

• Antihistamines

Infections

• Blood poisoning

• HIV infection

• Brain infection

• Meningitis

• Prion infections

• Late-stage syphilis

• Any acute or chronic infection

While there are clearly many possible causes, they all lead to altered brain structure and/or changes in the way the brain and nervous system function. Specific examples include:

• Brain inflammation

• Atrophy of certain brain regions

• E.g. hippocampus, prefrontal cortex

• Build-up of amyloid plaques and other proteins

• Decreased connectivity between nerve cells

• Decreased brain blood flow

Symptoms

In general, symptoms of neurocognitive disorders all center around cognitive impairment or cognitive deficits. Areas that may be affected include attention, memory, language, perception, and social cognition. Listed below are symptoms that may occur in mild and major neurocognitive disorder: ^{[2] [4]}

• Difficulty paying attention

• Easily distracted

• Trouble recalling information

• Difficulty with mental calculations

• Thinking takes longer than normal

• Tasks take longer than normal to complete

• Increased effort to complete tasks

• May require assistance

• Trouble following conversations

• Repeating oneself often

• Difficult expressing oneself

• May use general rather than specific language

• Difficulty remembering/recalling names of people

• Grammatical errors

• Significant difficulty doing previously familiar activities (e.g. driving, using tools)

• Trouble navigating in familiar environments

• Gets lost more than normal

• Behavioral or attitude changes within social settings (e.g. insensitivity, decreased empathy, unusually focused interests/topics)

• Difficulty recognizing social cues

In mild neurocognitive disorder, these symptoms are subtle to moderate. They cause negative impacts, but individuals can still function on their own. However, in major neurocognitive disorder, these symptoms cause severe impairments and require assistance from others to carry out daily living tasks.

Symptoms of delirium are related to the above symptoms, although the range of symptoms is much narrower. These include: ^[2]

• Trouble focusing

• Difficulty shifting and sustaining attention

• Reduced awareness in one’s environment

• Additional disturbances in cognition, such as memory deficits, disorientation, or decreased perception ability

Risks and Complications

Neurocognitive disorders have a number of risks and complications. This is especially true for mild and major neurocognitive disorders, given that they are often progressive and persistent in nature. ^[4]

Many people with mild neurocognitive disorder will end up with major neurocognitive disorder, which can lead to a number of complications. It can lead to an inability to perform daily living tasks, often requiring the assistance of others. People with neurocognitive disorders may also experience personality changes, agitation, mood changes, and other factors that disrupt their own well-being and the relationships with those around them, causing a lot of tension and stress. It may also cause depression, anxiety, loneliness, and anger. ^{[2] [4]}

The impairments in neurocognitive disorders also pose a number of personal safety risks, such as the risk of fracture due to falls or injury from driving or operating tools incorrectly. In addition, the complications of neurocognitive disorders may lead to inadequate nutrition, difficulty swallowing, incontinence, pneumonia, infections, and other physical issues. ^[4]

Diagnosing Neurocognitive Disorders

Diagnosing neurocognitive disorders involves multiple steps, including a mental status examination, medical history overview, and possible lab tests, such as blood work or brain scans. A thorough diagnostic process is essential to rule out other causes and to gain a complete picture of the individual’s symptoms and overall functioning.

Neurocognitive Disorder Assessments and Tests

The first assessment used is typically a cognitive evaluation screening tool. Examples of such tools include:

• Mini-Mental Status Examination: This exam has 11 questions that assess 5 key areas of cognitive function, such as attention, calculation, and recall.

• Montreal Cognitive Assessment: This assessment includes a variety of mental exercises to test for memory, attention, language, and other key cognitive domains.

• Rowland University Dementia Assessment Scale: This scale assesses 6 components of cognition, including memory, judgment, and visuospatial orientation.

• Mini-Cog: This is a very quick cognitive test consisting of word recall and a clock drawing exercise.

These tools can’t provide a diagnosis, but they do provide an initial understanding of symptoms and help to indicate possible cognitive impairment. In some cases, more in-depth neuropsychological testing is used to gain further information, especially in subtler or harder-to-diagnose cases. ^[4]

A variety of laboratory tests are also used within the evaluation of neurocognitive disorders, including: ^[4]

• Complete blood count

• Urinalysis

• Metabolic panel

• Vitamin B12

• Folic acid

• Thyroid function tests

• Serological tests for syphilis and HIV

Brain imaging may also be implemented in the diagnostic process, especially if the person is relatively young, showing atypical or rapidly advancing symptoms, or if the diagnosis isn’t definitive. Brain imaging tests that may be ordered include: ^{[3] [4]}

• Brain MRI

• Head CT scan

• Electroencephalogram (EEG)

• Lumbar puncture (“spinal tap”)

• PET, SPECT, and fMRI

• These three aren’t often used due to their high cost

Complications of Diagnosing Neurocognitive Disorders

There are several complications when it comes to diagnosing neurocognitive disorders. For one, it’s sometimes difficult to differentiate between normal cognition and mild neurocognitive disorder, as well as between mild and major neurocognitive disorder, due to the fact that differences may be slight. In addition, especially in older individuals, symptoms of cognitive decline can be confused with the normal course of aging, especially if they’re mild. ^[2]

Also, other disorders may have similar symptoms as neurocognitive disorders, such as major depressive disorder, specific learning disorder, and some neurodevelopmental disorders. It can also sometimes be difficult to distinguish persistent delirium from mild or major neurocognitive disorder.

Treatment Options

Treatment for neurocognitive disorders depends in part on the exact cause. Furthermore, some neurocognitive disorders are short-term and reversible, while others are progressive and will get worse over time. Therefore, treatment for reversible conditions focuses on resolving symptoms, while treatment for progressive conditions focuses on minimizing symptom severity and promoting overall health as much as possible.

The most common medications used for neurocognitive disorders are cholinesterase inhibitors and NMDA antagonists. Examples of these are: ^[4]

• Cholinesterase inhibitors: Donepezil, galantamine, rivastigmine

• NMDA antagonists: Memantine

Sometimes, additional medications will be used to help combat anxiety, irritability, depression, aggression, and other commonly occurring mental symptoms. In these cases, antidepressants or antipsychotics may be implemented.

Treatment also often involves lifestyle modifications to optimize cognitive functioning and prevent declines where possible. This includes: ^[4]

• Adequate sleep

• Anti-inflammatory diet

• Regular exercise

• Stress management techniques

• Maintaining health blood sugar, cholesterol, and blood pressure

• Treating any hearing or vision loss

Living with Neurocognitive Disorders

Living with a neurocognitive disorder is stressful not only for the individuals affected, but also for those around them. This is particularly true when the disorder is progressive and can’t be treated.

Regardless of severity and outlook, there are still things that can make living with neurocognitive disorders more manageable for the both individual affected, caregivers, and anyone else affected.

Tips for individuals with neurocognitive disorders include:

• Join a support group

• Try to have a routine

• Use reminders and other scheduling aids

• Maintain social relationships as best you can

• Practice a healthy lifestyle (e.g. sleep, exercise, healthy diet)

• Engage in cognitive exercises (“brain games”)

Tips for caregivers include:

• Ensure medication compliance

• Ensure healthy lifestyle practices are carried out

• Implement rules with respect to safety concerns (e.g. with driving, cooking, tool use)

• Monitor these closely

• Focus on reassuring and redirecting, rather than being overly demanding or correcting

• Practice patience and understanding

• Use clear, simple language when communicating