A neurocognitive disorder, previously known as dementia, refers to a wide range of disorders that affect the brain.

All neurocognitive disorders (NCDs) feature “an acquired cognitive decline in one or more cognitive domains.” These disorders tend to involve problems with thinking, reasoning, memory, and problem solving.

Some types, such as Parkinson’s disease, can lead to physical disabilities.

There are major and mild neurocognitive disorders (NCDs), depending on how severely the symptoms impact a person’s ability to function independently in everyday activities.

Factors underlying different types of neurocognitive disorder include metabolic and endocrine conditions, nutritional deficiencies, substance abuse, trauma, and infections.

This type of condition is more likely to affect older people, but it is not part of the normal ageing process. It can affect younger people too.

This article will look briefly at some different types of neurocognitive disorder.

Fast facts on neurocognitive disorders

Here are some key points about neurocognitive disorders, or dementia. More detail is in the main article.

  • Dementia is a common term for conditions such as Alzheimer’s and other neurocognitive disorders.
  • These disorders affect the nerve cells and often impact a person’s ability to remenber, to reason, and to make judgments.
  • They usually develops as people age, but they can affect younger people too.
  • The exact cause of some types of neurocognitive disorder is unknown, but some lifestyle factors may reduce the risk.
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Neurocognitive disorders, previously known as dementia, can lead to confusion, memory loss, and sometimes physical challenges.

The Diagnostic and Statistic Manual of Mental Disorders Fifth Edition (DSM-5) classifies neurocognitive disorders (NCDs), or dementia, as mild or major, depending on how severe they are. A person may have, for example, major or mild NCD due to Alzheimer’s disease.

The term “dementia” is still used, but usually to refer to degenerative dementias that are more likely to affect older adults. It is now less likely to be used for conditions resulting from, say, trauma or substance abuse, that may emerge in younger patients.

Some symptoms are common to different types of disorder, but others are specific to the condition. They all involve some degree of neurological impairment.

Here are some of the main types of disorder.

Alzheimer’s disease

Alzheimer’s disease is the most common cause of neurocognitive disorder. It affects between 60 and 80 percent of all people with dementia.

Alzheimer’s currently affects some 5.5 million people in the United States (U.S.). Around 200,000 of these people are under 65 years of age, with younger-onset Alzhiemer’s.

In the early stages, people with Alzheimer’s may find it hard to remember recent events, conversations, and names of people. They may also experience depression.

In time, it becomes harder to communicate, and judgment may become impaired. The person may feel disoriented and confused. Their behavior could change, and physical activities such as swallowing and walking might become harder.

Creutzfeldt-Jakob disease

This condition represents a number of brain diseases that cause problems throughout the body. They are thought to be triggered by prion proteins. A prion is neither a virus nor a bacterium, but it can cause a disease.

Types of Creutzfeldt-Jakob disease (CJD) include bovine spongiform encephalopathy (BSE), or “mad cow disease.” Symptoms include rapid memory, behavior, and movement changes. It is a rare and fatal condition.

Dementia with Lewy bodies

The symptoms can resemble those of Alzheimer’s disease, but there may also be sleep disturbances, visual hallucinations, and an unsteady walking pattern.

Lewy bodies are collections of protein that develop inside nerve cells and prevent them from functioning properly.

Frontotemporal dementia

This condition can trigger changes in how people behave and how they relate to others. It can also cause problems with language and movement.

Frontotemporal dementia often emerges around the age of 60 years, but it can appear in people who are in their 20s. It involves a loss of nerve cells.

Parkinson’s disease

Parkinson’s is a motor system disorder. The hallmark signs include trembling, especially tremor in the hands. It can also involve depression and behavioral changes.

In the later stages, the individual may have difficulty speaking and sleep disturbances.

Huntington’s disease

Huntington’s is a genetic disorder that results from a defect on chromosome 4. It can lead to mood changes, abnormal movements, and depression.

The person may experience an ongoing decline in thinking and reasoning skills. There could be slurred speech and problems with coordination. It tends to appear between the ages of 30 and 50 years.

Mixed dementia

Mixed dementia means the condition has more than one cause. Examples include Lewy body dementia combined with vascular dementia or Alzheimer’s disease.

Normal pressure hydrocephalus

This happens when a buildup of cerebrospinal fluid causes pressure in the brain.

Symptoms can include memory loss, problems with movement, and the inability to control urination. It can happen at any age, but it is more common among older people.

Vascular dementia

Also known as post-stroke dementia, this can happen after a stroke, when there is bleeding or vessel blockage in the brain. It affects a person’s thinking and physical movements.

According to the Alzheimer’s Association, early symptoms may include an inability to organize, plan, or make decisions.

Wernicke-Korsakoff syndrome

This can result from a chronic deficiency of vitamin B1, or thiamine. It is most common in those who chronically abuse alcohol. The effects of alcohol and a poor diet are likely to contribute.

The chief symptom is severely impaired memory, including long-term memory gaps, which the person may try to fill in with incorrect versions of what they think happened. This unintentional lying is known as confabulation.

Various factors can lead to different kinds of NCD, but some form of nerve cell damage is common to all these conditions. How these changes impact an individual will also depend on where in the brain the damage occurs.

Alzheimer’s disease: The exact cause is not known, but the person will have amyloid plaques and tangles in their brain.

Lewy body dementia: Lewy bodies are clumps of protein that develop in people with Lewy body dementia, Alzheimer’s, and Parkinson’s disease.

Vascular dementia: This results from damage to blood vessels in the brain.

Metabolic or endocrine issues: Thyroid problems, for example, can lead to dementia if the body is not able to absorb certain nutrients. Nutritional factors, such as a low intake of vitamin B12, can also play a role.

Infections: Some types of infection can lead to some kinds of dementia. Multiple sclerosis (MS) is an immune condition in which the body attacks its own nerve cells. If damage occurs in the brain, neurocognitive damage can result.

Traumatic brain injury: This has been linked to NCDs in footballers.

While the cause of Alzheimer’s, the most common cause of dementia, remains unknown, a number of lifestyle choices can help to prevent other forms of the condition.

The following factors could all reduce the risk of nerve damage:

  • avoiding excessive alcohol consumption and smoking
  • maintaining a healthy blood pressure level
  • controlling diabetes

Seeking medical help for depression, infections, and traumatic brain injury (TBI) can also reduce the chance of developing some types of dementia.

Complications can include a deterioration of physical health, as the individual becomes less able to take care of themselves or to eat properly.

Although it is common for the symptoms of an NCD to worsen gradually, a person can continue to live independently for some time following a diagnosis.

Here are some tips for staying active:

Social contact: It is important to remain in contact with others and to continue to see friends and family. Joining a support group can help.

Sleep: Sleep may pose a problem. Good sleep hygiene tips include keeping to regular bedtimes, not napping during the day, and avoiding alcohol or caffeine at night.

Keeping active: Follwoing a diagnosis, many people can continue doing the things they have always enjoyed, such as walking or gardening.

Getting support: In time, the person may need help at home. Residential care may be necessary when independent living becomes too difficult.

Family or friends who care for a person with an NCD may wish to consider discussing future plans with them while they are still able to think clearly and to make decisions.

As the aging population grows, fears have arisen of a “dementia explosion,” where large numbers of people will experience NCDs.

However, findings of a large study of over 21,000 American adults, published in 2017, suggest that the prevalence of dementia fell from 11.6 percent in 2000 to 8.8 percent in 2012.

The researchers conclude: “Population brain health seemed to improve between 2000 and 2012.”