Fast facts

  • Dementia is a decline in a person's brain functions, usually memory and thinking, caused by damage to brain cells. It is usually encountered at older ages.
  • There are many forms and many causes of dementia. The symptoms of dementia, their severity and their progress vary depending on the type of dementia and the region of the brain that is affected.
  • The most common signs of dementia are significant problems in memory, language and the ability to carry out tasks.
  • Generally, there is no cure for dementia, but early diagnosis and management can improve quality of life. Treatment of people with dementia is focused mainly on supporting them and their family, and cautiously using medications when appropriate.

What is dementia?

Dementia is a permanent decline in brain function, usually memory and thinking. Dementia is caused by damage to nerve cells in the brain. 

Most people experience some degree of memory loss in older age; however, in a person with dementia, memory loss becomes so severe that it has a serious effect on their daily life.

The human brain, parts of the brain.

The human brain.

Types and causes

Brain damage can take many different forms and have many different causes. The most common types of dementia are:

Alzheimer's disease

Alzheimer's disease is the most common type of dementia. 

Although the exact cause of this condition is not undersstood, it is known that proteins called amyloid and tau build up in the brains of people with Alzheimer's disease. It is thought that this impairs the normal function of the brain, eventually leading to the death of brain cells.

Alzheimer's disease is progressive: its symptoms can appear and gradually become more serious over time. It can sometimes take a long time before the symptoms are noticed. 

Some of the more common symptoms of Alzheimer's disease include:

  • Persistent and frequent short-term memory loss;
  • Language difficulties, such as struggling to find the right word, or not being able to understand conversations;
  • Disorientation, even in well-known places;
  • Problems with carrying out familiar tasks;
  • Fast and unpredictable changes in mood;
  • Being less interested in hobbies and activities previously enjoyed, and;
  • Changes in sleep patterns or amount of sleep.

Vascular dementia

Vascular dementia is one of the most common types of dementia. The symptoms of vascular dementia can appear either suddenly after a major stroke, or gradually after multiple small strokes.

The cause of vascular dementia is reduced flow of blood to the brain and brain injury.

The symptoms of vascular dementia may be similar to those of Alzheimer’s disease, but may also include:

  • Physical weakness or paralysis as a result of stroke(s);
  • Seizures;
  • Visual changes;
  • Problems with communication;
  • Reduced ability to think and concentrate;
  • Problems with walking, and;
  • Incontinence.

Lewy body dementia

Lewy body dementia is a common type of dementia that has similar symptoms to both Alzheimer's disease and Parkinson's disease. Lewy bodies are small deposits of protein that build up inside nerve cells of the brain. 

The symptoms of Lewy body dementia may vary, according to the region of the brain the protein accumulates in. People with Lewy body dementia are less likely to experience the short-term memory loss experienced with Alzheimer's disease.

Some of the more common symptoms of Lewy body dementia may include:

  • Changes in awareness and concentration;
  • Problems with planning, decision-making and organisation;
  • Problems with visual perception, such as judging distances;
  • Sleep disturbances, and;
  • Problems with movement, tremors, or an abnormal gait (walk).

Some other common medical conditions that may cause dementia include:

Parkinson's disease

Parkinson's disease occurs as a result of damage to the cells that produce dopamine, which reduces the amount of dopamine in the brain. Dopamine is an important molecule involved in movement, decision-making and planning.

As Parkinson's disease progresses, memory and reasoning gradually decline, leading to dementia.

Frontotemporal lobar degeneration

Frontotemporal lobar degeneration occurs when abnormal deposits of proteins lead to nerve cell damage in the frontal and temporal lobes of the brain. The frontal and temporal lobes control planning and judgement, emotions and understanding speech. Degeneration of these areas leads to a diverse group of conditions known as frontotemporal dementia. These are marked by changes in personality, impulsive behaviour, lack of emotions, and/or difficulties with language. These conditions are not common, and cause dementia at a younger age, particularly between 50-60 years of age. 

Huntington's disease

In Huntington's disease, a defective gene leads to abnormal production of a protein called huntingtin. when this protein builds up in the brain, it damages the brain cells responsible for controlling movement, behaviour and thinking.

Huntington's disease dementia is marked by difficulties with thinking, in addition to abnormal jerky movements and psychiatric symptoms ranging from antisocial behaviour to depression, mania or psychosis.

Alcohol-related dementia (Wernicke-Korsakoff syndrome)

With alcohol-related dementia, it is unclear whether alcohol is directly toxic to nerve cells in the brain, or whether the damage to the cells is caused by the reduction of vitamin B1 (thiamine). This vitamin is important for normal brain function.

The symptoms of alcohol-related dementia vary between individuals, but commonly include personality changes, memory problems and confusion. Occasionally, some individuals have a characteristic symptom of imagining and sharing stories of things that they believe happened. This is known as 'confabulation'.  

Creutzfeldt-Jakob disease

Creutzfeldt-Jakob disease is a rare and fatal condition. It is believed to be caused by prions, which are proteins that can have both a harmless normal form and an infectious form, which can cause disease.

The structure of the infectious form of a prion causes damage to nerve cells in the brain. This leads to a rapid decline in thinking, reasoning and muscle coordination.

Brain injury

Severe traumatic brain injury can result in bleeding and damage to neurons within the brain. Such damage can lead to permanent impairment in thinking and learning.  

Reversible causes

Some people may have symptoms that mimic dementia, but are related to other conditions such as depression and/or delirium. Depression is more than a low mood; it can also cause problems with concentration, difficulties with memory and thinking, reduced motivation and sleep difficulties. Because of this overlap in symptoms with dementia, telling these two causes apart can often be difficult. However, when the symptoms are due to depression, effective treatment for depression can often resolve these symptoms.

Delirium is generally an acute shift in mental function that can have numerous possible causes, such as:

  • Anaemia;
  • Thyroid disorders;
  • Nutritional disorders, and;
  • Infection.

Many of these conditions will improve with treatment and the delirium associated with them may be reversible, if significant brain cell damage has not yet occurred. 

Risk factors

Risk factors for dementia include:

  • Smoking;
  • Heart disease;
  • Diabetes;
  • High blood cholesterol;
  • Family history, especially of Huntington's disease and Alzheimer's disease;
  • Down syndrome;
  • Traumatic brain injury, and;
  • Alcohol abuse.

Signs and symptoms

The symptoms of dementia, their severity and their progress vary depending on the type of dementia and the region of the brain that is affected.

The most common signs of dementia are significant problems in memory, language and the ability to carry out complex tasks. People with dementia can also show changes in behaviour and social functioning.

At first, dementia usually appears as forgetfulness. Other common symptoms associated with dementia may include: 

  • Confusion;
  • Difficulty carrying out everyday tasks;
  • Social withdrawal and lack of emotion, and;
  • Progressive and frequent memory loss.

Patients with dementia can also experience:

  • Behavioural changes, such as agitation and aggression;
  • Sleep disturbances;
  • Constipation;
  • Problems with movement, and;
  • Psychotic symptoms, such as hallucinations and delusions.    

Methods for diagnosis

Patient history and cognitive testing

To help make an accurate diagnosis of dementia, a healthcare provider will:

  • Obtain a detailed personal and family history; 
  • Complete a physical examination, including examination of the nervous system, and;
  • Perform mental function test(s) to assess brain function.

Laboratory tests

To eliminate other potential causes of confusion and behaviour that can mimic dementia, the following laboratory tests may be performed:

  • Full blood count (FBC) – to rule out anaemia;
  • Erythrocyte sedimentation rate (ESR) – to screen for inflammation;
  • Basic metabolic panel – to rule out abnormal levels of sodium, calcium and glucose;
  • Thyroid-stimulating hormone (TSH) – to rule out abnormal functioning of the thyroid gland;
  • Serum vitamin B12 and folate – to exclude nutritional deficiencies;
  • Urine drug test – to exclude recreational drug use, and;
  • An infection screen – this may include a urine test for urinary tract infection, a chest X-ray to rule out pneumonia, and blood cultures to rule out bacterial infection in the blood (sepsis).

Brain imaging

Brain imaging, including computerised tomography (CT) and magnetic resonance imaging (MRI) scans, may be used to diagnose dementia. These scans provide different kinds of images of the brain. The CT scan uses X-rays to produce a 3D image of the brain, while the MRI uses a magnetic field. The scans:

  • Help identify some causes of dementia including haemorrhages, tumour or strokes;
  • Distinguish between the different types of dementia, and;
  • Establish a baseline to monitor for brain degeneration.

Other tests

In patients with atypical symptoms, such as those of younger age or with rapidly progressive dementia, a more extensive evaluation may include lumbar puncture, electroencephalogram (EEG), broader blood tests and, rarely, brain biopsy. 

Types of treatment

The treatment for dementia depends on its cause and severity. Generally, there is no cure, but early diagnosis and management can improve the quality of life for the person with dementia. 

Treatment of people with dementia is focused mainly on supporting them and their family, and cautiously using medications when appropriate.

Supportive care

Creating a supportive and safe environment for a person with dementia is an important part of treatment. Households should be clutter-free and organised, to remove hazards and maintain order. Following a daily schedule and/or using a checklist creates a habit of ensuring that daily activities are completed. 

Regular exercise, such as 30-minute walks, improves mood, promotes restful sleep and maintains overall health. Exercise may need to be supervised, depending on the severity of the dementia, to prevent wandering and/or injury. 

Promoting a high-calorie diet and plenty of water helps to overcome the malnutrition and dehydration that can occur with moderate to advanced dementia, as the person forgets to or loses interest in eating and drinking. Also, a high-fibre diet with plenty of fluid and exercise can help prevent constipation, which is a common problem in people with dementia.

Seeing a doctor to simplify medication regimens, such as eliminating unnecessary medications, reducing to once-daily dosing and/or organising medications into easy-to-take packaging, can help to improve compliance.  

Caring for a person with dementia

Supporting and caring for a person with dementia can be a very difficult and demanding task. Commonly, as the dementia advances and symptoms worsen, providing the physical and emotional support can overwhelm carers. There are services available for carers and families of people with dementia that can provide assistance. It is important to seek help from such services and/or a doctor early, before facing any difficulties. Occasionally, the care needs for a person with dementia may overwhelm what a carer can provide, and/or limit the person's independence at home, which leads to the often difficult decision to place the person with dementia into a care facility. These facilities are well-established to care for such people and provide a comprehensive, caring environment with nurses, doctors and other healthcare professionals. 


For some types of dementia, specific medications can help slow the progression of memory decline. These medications do not cure the condition, but help to improve the quality of life. Like all medications, they need to be used with caution, as their side effects can potentially worsen the person's symptoms.  

These specific medications are mainly indicated for people with Alzheimer's disease, at varying stages of their condition. The medications fall into two broad categories: 

  • Cholinesterase inhibitors work to increase levels of the neurotransmitter, acetylcholine, in the brain, which is often reduced in patients with Alzheimer's disease. They help improve brain function and slow the progression of the condition. This medication is prescribed for patients with mild to moderate Alzheimer's disease, who show an improvement with use over six months. Potential side effects include diarrhoea, nausea and vomiting, slow heart rate and sleep disturbance. 
  • Memantine acts to block an important receptor in the brain known as N-methyl-D-aspartate (NMDA), which is involved with learning and memory. It is prescribed for patients with moderate to severe Alzheimer's disease. Generally, memantine is safer than cholinesterase inhibitors, with dizziness as the most common side effect.    

Other medications can occasionally be used to treat accompanying symptoms of dementia, such as: 

  • Behavioural issues such as agitation, aggression and psychotic symptoms – these can be managed with anti-anxiety and/or antipsychotic medications; 
  • Depression – this is common in people with dementia, which may be related to the initial diagnosis and/or result from the reduction of neurotransmitters in the brain. Managing the depression is important for better outcomes; using non-drug interventions such as exercise, and antidepressant medications if needed, can help, and; 
  • Sleep disturbance – persistent wakefulness and night-time restlessness can be distressing for the person with dementia and disturbing for carers. Many of the medications prescribed for people with dementia can cause excessive sedation during the day and lead to inability to sleep at night. Generally, sleep medication is discouraged, as it provides no long-term solution and can cause side effects. However, small doses of melatonin can sometimes be helpful.   

Potential complications

People with dementia usually do not die from dementia itself, but from its associated complications. Late stages of dementia, especially Alzheimer's disease, are associated with frequent bouts of pneumonia and this is often the cause of death.

Other complications may include:

Urinary tract infections (UTIs)

More severe stages of dementia may be associated with urinary incontinence. The weaker flow of urine and lower likelihood of completely emptying the bladder increase the risk of developing a urinary tract infection. Also, treatment for urinary incontinence may include the insertion of a urinary catheter, which is known to increase the risk of contracting a urinary tract infection. Urinary tract infections can lead to other serious and fatal complications, including sepsis and multi-organ failure.


The mobility problems and disorientation that is associated with some forms of dementia may increase the likelihood of falls. Falls can cause fractures or head trauma, and the lengthy period of immobilisation required for recovery from these injuries can lead to further complications such as thromboembolism and pneumonia.

Weight loss

People with more severe dementia may experience considerable malnutrition, which may lead to weight loss, impaired immune system, loss of muscle tone and the loss of independence. 


The outlook for dementia depends on its cause, and the prognosis can also vary according to the individual. If the symptoms mimicking dementia are caused by nutritional deficiencies or an infection, appropriate treatment may achieve a full recovery. For those with vascular dementia, the deterioration of memory may remain stable for years after the initial stroke and treatment may help reduce the likelihood of having further strokes. For other causes of dementia including Alzheimer's disease, Parkinson's disease, Creutzfeldt-Jakob disease, frontotemporal lobar dementia and Huntington's disease, medication may help reduce the rate of disease progression; however, the condition will gradually become worse and lead to its terminal stage. The time over which a condition progresses to its terminal stages may vary widely, ranging from several months to several years.


Although the causes of some types of dementia are yet to be clearly understood, the likelihood of developing dementia may be decreased by:

  • Maintaining a high level of cardiovascular health;
  • Quitting smoking;
  • Avoiding excessive alcohol consumption;
  • Avoiding head trauma;
  • Maintaining a healthy cholesterol level, and;
  • Eating a balanced and healthy diet.

There is yet no conclusive evidence that mental training or brain games can help prevent or delay the onset of dementia.

Last Reviewed: 03/10/2018

Reproduced with permission from Health&.