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Dementia and Delirium, including Alzheimer’s

“Has anyone seen my wallet?” “What time do I have to go to the dentist?” “What’s the name of that movie we went to last week?” We all ask these sorts of questions from time-to-time no matter our age; and not having a perfect memory is perfectly normal. It's also normal that our longer term memory, as well as our ability to remember things that only occur occasionally, fade a little as we age. Nevertheless, as we get into our sixties, many of us worry that forgetfulness or difficulty paying attention are signs of worse things to come. One of the most widespread fears as we age is dementia due to Alzheimer’s disease.
Both dementia (including Alzheimer’s) and delirium are both common causes of memory loss, impaired thinking and understanding (cognition) and impaired behaviour. They are distinct disorders but may be difficult to tell apart:
  • Dementia is a group of symptoms that mainly affects memory, cognition and social interactions, and the ability to do everyday tasks. Symptoms start gradually often with no clear beginning, and are usually permanent.
  • Delirium, on the other hand, typically begins suddenly with a noticeable start point. It mainly affects attention, and often resolves after a few days or weeks, although it can last longer.

Structure, function and brain damage in dementia

Your brain is your body’s control centre. It is full of millions of interconnected brain cells, called neurons that receive, process, and send messages that control and coordinate almost everything that you do. Your brain is divided into three main parts, the brain stem, cerebellum and cerebrum. These different regions are responsible for different functions, such as movement, speech, sense perception, emotions, heart rate, cognition and memory. Information travels back and forth from the brain to the body along neurons, in the form of electrical impulses. When a nerve impulse reaches the end of a neuron a chemical neurotransmitter is released, which stimulates the electrical nerve impulse in the next neuron, allowing it to “jump” from one neuron to the next. Neurons in different parts of the brain use different neurotransmitters to transfer information. Some neurotransmitters stimulate brain activity, others calm the brain, and some do both. When your brain is functioning well, these neurotransmitters are all in balance.
Diagram showing regions of the brain affected by dementia
Image of neurotransmitters traveling across a synapse
Dementia may occur anytime neurons get damaged. The damage may be anywhere within the brain, and in more than one area at the same time. Most dementias are caused by neurodegenerative diseases, most commonly Alzheimer’s disease, Lewy body dementia and frontotemporal dementia. These diseases cause clumps of abnormal proteins to build up inside neurons, damaging them, and causing them to slowly degenerate and die. Not surprisingly, this disrupts the production of neurotransmitters and interrupts brain signals. In addition to these, vascular dementia is another common cause of progressive dementia. In this case, brain damage occurs when the blood supply to the neurons is reduced or blocked, again causing them to malfunction or die. Blood vessel damage and blockage may result during a stroke, or may be caused by high blood pressure or other blood vessel disorders. There are also several other rare neurodegenerative diseases, and many other less common causes of dementia, such as infections, or dietary deficiencies.
Delirium is an acute, transient, and usually reversible brain malfunction. What exactly happens inside the brain of someone with delirium is not well understood; although, it is thought to be brought on by multiple neurotransmitter imbalances, which alter your normal brain activity.

Symptoms of dementia and delirium

Dementia symptoms affect people differently depending on the area or areas of the brain that are affected, and may be progressive or reversible depending upon the cause of the damage. Sometimes the symptoms are very similar to those of delirium, making diagnosis somewhat tricky, and it is fairly common for a person with dementia to develop delirium.
Dementia: symptoms usually start gradually, are fairly constant on a day-to-day basis, and slowly and steadily become worse over the course of about a decadeDelirium: symptoms usually appear over a few hours to a few days, and may fluctuate on and off during the day, and often occurs at night.
Cognitive symptoms include:Cognitive symptoms include:
Memory lossMemory Loss
Difficulty speaking and communicatingDifficulty speaking and communicating
Difficulty with complex tasksRambling or nonsense speech
Difficulty planning and organizingDifficulty reading and writing
Loss of coordinationWandering attention
Becoming easily distracted
Becoming withdrawn
Psychological symptoms include:Psychological symptoms include:
Personality changesInability to focus
Inability to reasonInability to reason
Inappropriate behaviourReduced awareness of the environment
HallucinationsDisturbed sleep
Fear, anxiety, anger or depression
Delirium is usually transient rather than permanent, although how well you recover often depends on how well you were beforehand — if you were in good health before it happened, you are more likely to have a full recovery. Unfortunately, for some people, particularly those who are critically ill, delirium may lead to significant memory loss and decrease in thinking skills, as well as a general decline in health, poor recovery and increased risk of death.
A diagram that details what each region of the brain controls

What causes dementia and delirium?


Four diseases account for most cases of dementia: Alzheimer’s disease (about 50-60% of cases), vascular dementia (about 15-20% of cases), Lewy body dementia, and frontotemporal dementia.start superscript, 1, end superscript Each of these have different characteristics:
  • Alzheimer’s symptoms usually start in your mid to late 60s, although a small proportion of people get early onset Alzheimer's, with symptoms starting in their 40s or 50s. This form of Alzheimer’s has a strong genetic link and typically runs in families.
  • Vascular dementia is rare if you are under 65, but usually starts more suddenly than Alzheimer’s. Diagnosis may be complicated by the fact that you have Alzheimer’s or another dementia at the same time. People at risk for vascular dementia often have a history of smoking, cardiac dysrhythmia, hypertension, diabetes, and coronary artery disease.
  • Lewy body dementia: Lewy bodies are abnormal clumps of protein that build up in neurons causing brain signalling malfunctions; they are often found in the brains of people with Alzheimer’s and Parkinson’s disease (primarily a movement disorder). Lewy body dementia is similar to Alzheimer’s, but can be distinguished by unique symptoms such as rapid eye movement sleep behaviour disorder, and fluctuations between confusion and clarity.
  • Frontotemporal dementia often has an earlier onset than Alzheimer’s, generally in your 50s or early 60s. The brain damage occurs at the front of your brain in regions that control personality, behaviour, and language.
Exactly why we get these dementias remains a puzzle, although there are likely genetic links in many cases. Other rare conditions have also been linked to dementia including Huntington’s disease, Creutzfeldt-Jakob disease, and Parkinson’s disease, as well as traumatic brain injury.
Additionally, there are a variety of other reasons you may get dementia when the symptoms are often reversible. These include infections (e.g., meningitis, or syphilis), nutritional deficiencies, reactions to medications, brain bleeds, substance abuse, and poisoning. It is also possible that malfunction of other vital organs including the liver or kidneys can disrupt brain function causing dementia.
As an older adult, any condition that ends up in a visit to the hospital increases your risk for delirium, and up to 80% of people who are critically ill will be delirious at some time during their hospital stay.squared There are many different conditions that can trigger delirium with most common including dehydration, acute infections, such as urinary tract infection or pneumonia, prescribed drugs including antidepressants, sleeping pills and narcotics, and alcohol or substance abuse or withdrawal.
A diagram showing the causes of dementia and delirium

How many people have dementia and delirium?

Dementia: Worldwide, there are around 50 million people living with dementia, and with 8 million new cases every year; as the average lifespan is steadily increasing, dementia is increasing fast in many countries.cubed Overall, almost 1 in 10 people over the age of 60 have dementia, and the prevalence increases rapidly with age.start superscript, 1, end superscript Women are at slightly more risk for it than men, and your chances increase if you are obese, have diabetes, high blood pressure, or other cardiovascular risk factors.start superscript, 1, end superscript
A graph illustrating the predicted number of cases of dementia in various regions of the world.
Delirium: Delirium is very common in the hospital setting, especially when you are older and unwell. In fact, almost half of older patients are delirious when they are admitted, or develop delirium while they are there.2 Like dementia, delirium increases significantly with age.4 In contrast to dementia, delirium is a little more common among men than women.

Are there ways to prevent dementia and delirium?

Dementia: We don’t know for sure how to prevent dementia, but a healthy active lifestyle that includes keeping your mind and body active, and that keeps you socially connected may be of benefit. Other steps you can take that may also reduce your risk are to quit smoking, lower your blood pressure, and eat a healthy diet that maintains a good balance of nutrients and vitamins, all of which may indirectly reduce your risk.
Delirium: The best way to prevent delirium is to remove the triggers. In a hospital setting this could include systems that maintain as calm and quiet an environment as possible, while providing the individualized support and medical care that is necessary, and when possible avoiding medications known to trigger delirium.

What are the treatments for dementia and delirium?

Dementia: Memory loss and other symptoms of dementia may have many causes, so after reviewing your medical history, and symptoms, your doctor will likely want you to undergo other tests to evaluate your thinking and movement skills, and possibly your mental health. In addition to this, you may need a brain scan to check to see if you have had a stroke or brain bleed, or whether or not you have a brain tumour, as well as various laboratory tests to check for any metabolic and nutritional problems.
Most types of dementia are incurable, but there are medications that regulate brain chemicals involved in brain functions including memory, judgement, and learning that may be helpful with controlling or reducing your symptoms. Two of the more commonly prescribed types of medicine are cholinesterase inhibitors and memantine, which is the first in a new class of drugs for the treatment of Alzheimer’s. Other medications are also available to treat any accompanying symptoms, and occupational therapists are experts at helping with strategies that improve coping with day-to-day challenges and quality of life.
Delirium: Your doctor will likely follow a similar process to that outlined above for dementia, to decide whether or not you are delirious. If you are, your treatment will be aimed at eliminating the underlying cause or causes, which for example could include treating an infection, or stopping or changing a particular medicine that you are taking to treat something else. Your doctor may also recommend additional supportive care, to ensure you stay hydrated, treat any pain you may have, keep you oriented with your surroundings, and help you get up and about again.

Consider the following:

Memantine is the first drug in a new class of drugs (called N-methyl-D-aspartate receptor, or NMDA receptor antagonists) that has been approved to treat moderate to severe Alzheimer’s disease. While cholinesterase inhibitors used to treat Alzheimer’s help raise the levels of the neurotransmitter known as acetylcholine, memantine works by regulating a chemical called glutamate. Glutamate is the salt of glutamic acid. It is an essential amino acid that is involved in many chemical processes that occur in living organisms, that lead to growth, production of energy, and elimination of waste. In the brain however, glutamate is an important neurotransmitter that’s involved in regulating almost everything your brain does including memory, cognition, and learning. For your brain to work well, glutamate has to be in the right place, at the right time, and in the right amount — too much or too little glutamate is harmful. In Alzheimer’s disease, excess glutamate accumulates when neurons get damaged, which can be devastating for functioning neurons. Memantine works by blocking the effects of too much glutamate, preventing cell death, and delaying some of the symptoms of moderate to severe Alzheimer’s disease. Because memantine has a different mechanism of action, it may be used in combination with cholinesterase inhibitors, which may improve outcomes for longer periods of time.

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