What is dementia? Causes and symptoms of dementia

Dementia is a syndrome affecting approximately 25 million people worldwide, a number that is estimated to rise to 76 million by 2030 and 135 million by 2050.

It is an acquired intellectual disorder characterised by progressive cognitive decline.

It has severe symptoms that incapacitate both the patient and his or her immediate family.

The term dementia is taken from the Latin and its literal translation means 'unthinking, unreasonable, insane, mad', a term first used by Dr Philip Pinel to describe a set of diseases in which intellectual abilities decline.

Dementia is an acquired disorder of the intellect. This distinguishes it from a congenital intellectual disorder called idiocy or retardation.

When talking about dementia, it is important to be familiar with its clinical expression, the dementia syndrome.

The dementia syndrome is characterised by a progressive deterioration of cognitive function. It is not related to a quantitative (unconsciousness, coma) or qualitative (hallucinations) impairment of consciousness.

The term 'cognitive function' is again taken from the Latin 'congnosco, congnoscere', which translates as 'to know, to become acquainted'.

Cognitive functions include:

• memory
• thinking
• intellect
• perception
• attention

The purpose of these cognitive functions is to:

• orientation in time and space
• the ability to communicate and understand speech
• to read, write, count
• visual-spatial and construction skills
• comprehension
• logical and abstract thinking
• judgement
• executive function (ability to plan some more complex and complex tasks)

In the case of dementia, there is progressive deterioration in all of these cognitive functions. However, the most well-known disorder associated with dementia is memory impairment.

Memory impairment is noticed by the patient or relatives. It is the most common reason why a patient seeks a medical examination. However, during a specialist examination, the doctor detects impairment in more than one cognitive function.

Dementia is typically found in older adults, but rarely it can be diagnosed at a younger age, even in children.

The generally agreed age at which dementia can be diagnosed is 3 years. This is the age at which a person's early psychomotor development is complete.

Approximately 5% of people aged 65 and older have dementia. As the decades pass, the incidence doubles to the age of 90, when almost half of people have dementia.

The types of dementia can be divided into several groups according to several criteria.

The age at which the first symptoms of dementia appear:

• Presenile dementia (onset before age 65)
• senile dementia (after the age of 65)

According to the location of the brain involvement:

• cortical dementia (e.g. Alzheimer's dementia) - Expressed mainly by impaired recall and memorisation, learning, impaired judgement, logical and abstract thinking. Apraxia (impaired learned movements, e.g. when dressing), acalculia (impaired counting), agnosia (impaired perception of objects with preserved vision) are present.
• subcortical dementia(Huntington's disease) - In this type of dementia, there is a mild memory impairment, particularly in the recall of older memories. Psychomotor slowing is predominant, with no acalculia, aphasia or apraxia. There is a marked impairment of executive functions, planning, motivation, attention and muscle tone from the onset of the disease.

Dividing according to the course:

• smoothly progressive (Alzheimer's dementia)
• rapidly progressive (vascular dementia)
• stationary dementia (after injuries)

According to the degree of severity, dementia is divided into:

• mild dementia
• moderate dementia
• severe dementia

According to the triggering cause, dementia is divided into:

• primary neurodegenerative dementia
• secondary dementia
• vascular dementia

Primary neurodegenerative dementia

One of the most common dementias, accounting for up to 60% of all dementias.

The cause is estimated to be a congenital predisposition to degeneration of cells and intercellular connections. The gradual disappearance of nerve cells and their connections leads to cerebral atrophy of cortical or subcortical centres.

Genetic predisposition to disease plays an important role in the pathogenesis of the disease, but the disease itself is not inherited. Only the predisposition to disease can be inherited.

For example, Alzheimer's disease has a genetically transmitted form. It is a familial dementia that is an autosomal dominant disease.

In practice, this means that the disease is inherited from parent to child and both sexes can be affected. If one parent has this dementia, the likelihood of a child being born with the mutation present is between 50-75%.

It is caused by mutations in three genes:

• the amyloid precursor protein gene, located on chromosome 21.
• the gene for presenilin-1, located on chromosome 14
• the gene for presenilin-2, located on chromosome 1

Parkinson's disease also has a hereditary form. It is a mutation in the gene for parkin (protein) or ubiquitin-C-hydrolase. These have a protective function in the brain.

When the gene is disrupted, the protein is damaged and is unable to perform its protective function in the cells. Therefore, the cells die more easily and quickly.

In order for dementia to become clinically apparent, a genetic predisposition requires a so-called trigger factor.

Such a triggering factor can be another physical illness, a change in the environment, a difficult social situation or an emotionally challenging period.

The most common primary degenerative dementias include:

• Dementia in Alzheimer's disease
• Dementia with Lewy bodies
• Frontotemporal dementia
• Dementia in Parkinson's disease
• Dementia in Huntington's disease

These types of dementia are also referred to as proteinopathies because they involve the deposition of a specific type of pathological protein. This protein is neurotoxic, causing aseptic inflammation that damages nerve cells in its surroundings.

Pathological proteins accumulated in the brain are:

• beta-amyloid
• tau-protein
• alpha-synuclein
• TDP-43 (transactive response DNA binding protein 43 kDa)

Each individual protein affects a different part of the brain and therefore the type of protein accumulating determines the clinical picture of dementia. The protein can be deposited inside the cell (intracellular) or outside the cell (extracellular).

When frontal and frontal subcortical localisations are affected, tau protein is involved. An example of tauopathy is frontotemporal dementia.

When subcortical centres such as the brainstem, basal ganglia and limbic system are affected, alpha-synuclein is involved. Among the best known alpha-synucleinopathies is Parkinson's disease.

Alpha-synuclein is a protein involved in the plasticity of neural connections - synapses.

In addition, alpha-synuclein has a tendency to spread through neurons throughout the brain. The mechanism of this transmission is probably the basis for the continuous progressive nature of the disease.

Pathological beta-amyloid is involved in damage to the posterior hemispheric cortical regions of the brain. A typical dementia with impaired beta-amyloid metabolism is Alzheimer's disease.

Secondary dementia

These are a diverse group of types of dementia. They are secondary to another disease, which may affect only the brain but also other organs or the whole body. They account for about 5-10% of all types of dementia.

Here is a brief overview of the diseases that lead to secondary dementia:

1. Metabolic diseases:

• Wilson's disease
• Acute intermittent porphyria
• Metachromatic leukodystrophy
• Uremic encephalopathy
• Hepatic encephalopathy

2. Endocrine diseases:

• Hypothyroidism, thyrotoxicosis
• Parathyroid gland dysfunction
• Adrenal dysfunction, e.g. Addison's disease, Cushing's syndrome
• Hypoglycemia

3. Infectious diseases:

• AIDS
• Neurosyphilis
• Lyme disease
• Progressive multifocal leukoencephalopathy (JCV virus)
• Iveomeningitis
• Herpetic encephalitis
• Prionoses

4. Pulmonary and haematological diseases:

• Chronic obstructive pulmonary disease
• Heart failure
• Anemia

5. Vitamin deficiencies:

• Hypovitaminosis D
• Hypovitaminosis of B vitamins, e.g. B1, B2, B3, B6, B9 and B12

6. Other disease states:

• Alcohol intoxication
• Normotensive hydrocephalus
• Oncological diseases
• Collagenoses

Vascular dementia

It forms the second most numerous group of dementias.

Vascular dementia is caused by impaired blood supply to the brain. Poorly blooded brain tissue has an inadequate supply of oxygen, leading to degeneration of nerve cells.

The situation arises, for example, after a sudden stroke or multiple cerebral ischaemia in subcortical areas.

Dementia is preceded by high blood pressure, atherosclerosis of blood vessels, obesity, hypercholesterolaemia and other vascular diseases such as lower limb ischaemia or myocardial infarction.

Symptoms of dementia can be of two types.

The first type of symptoms consists of cognitive impairment. In addition to these symptoms, there are also non-cognitive deficits (called neuropsychiatric), physical symptoms and symptoms of functional impairment.

Cognitive symptoms:

• gradual loss of memory
• impaired thinking
• impaired judgement
• poor orientation in space, time, disorientation by person
• speech impairment
• inability to learn new things
• cognitive impairment
• inability to perform complex motor tasks
• inability to name familiar objects

Neuropsychiatric symptoms:

• Depression
• restlessness
• apathy and disinterest
• mania
• delusions
• hallucinations
• exuberance
• aggression
• insomnia, or sleep rhythm disorder
• rudeness in social behaviour
• abnormal motor manifestations

Physical symptoms:

• urine leakage
• weight loss, food refusal, wasting
• loss of muscle mass
• extrapyramidal symptoms, i.e. tremor, rigidity, gait disturbances, etc.

Patient functionality:

• difficulty with complex tasks, e.g. driving, work habits
• inability to do household chores
• problems with personal hygiene, which requires a sequence of steps
• limitations in daily routine activities such as eating, dressing, combing...
• impaired communication, expressing one's needs and thoughts
• independent movement is almost completely impossible

Motor symptoms are not uncommon, especially in dementia where the subcortical centres of the brain are affected. At the beginning of the disease, symptoms are atypical, e.g. joint and muscle pain. They can lead to misdiagnosis.

Motor symptoms are typical of, for example, Parkinson's disease, where a constellation of symptoms is present:

• hypokinesia (restriction of range of movement) and the associated symptoms of bradykinesia (slowing of movement) and akinesia (impaired start of movement)
• rigidity (stiffness of muscles and joints)
• resting tremor
• postural disturbances

Symptoms usually appear on only one side of the body, on both upper and lower limbs. Gradually, as the disease progresses, they move to the other side of the body.

The diagnosis of dementia is a relatively complex process. It is carried out in several steps, from which a more detailed diagnosis of the disease is later made. The diagnosis of dementia is made by a specialist, namely a neurologist or psychiatrist.

A detailed initial examination is essential. The first-contact doctor plays an important role, as he or she may notice small signs. Alternatively, a family member accompanying the patient may confide in him or her.

The interview with the patient or his/her family focuses on cognitive delay, neuropsychiatric symptoms and the extent to which they interfere with the patient's normal life.

An important feature is the nature of the onset of symptoms, whether it was sudden or whether the change occurred gradually and gradually.

The family is an indispensable link in the diagnosis of dementia. It provides more objective information about the triggering or exacerbating factors and the course of suspected events.

Cognition screening tests follow. The most commonly used are the Mini Mental State Examination (MMSE), the Montreal Cognitive Assessment (MoCA), the Clock Drawing Test (CDT), verbal fluency tests, or others.

Of the imaging tests, MRI of the brain has the greatest predictive value, demonstrating brain atrophy in locations characteristic of a particular type of dementia.

It also allows us to assess the state of the blood vessels and their changes, which may also be involved in the development of vascular or secondary dementias.

CT scanning of the brain has now been replaced by the more detailed MRI, but it is still useful in acute diagnosis and is used to rule out other processes in the brain, such as haemorrhage, tumour, hydrocephalus and others.

Genetic testing is important if the dementia has an unusually rapid progression or if the patient is young. For example, genetic mutations in the amyloid precursor protein gene, the presenilin-1 gene or the presenilin-2 gene can be detected.

Secondary dementia is caused by the patient's other chronic disease.

It is very important to distinguish diagnostically between primary and secondary dementia. Secondary dementia is potentially reversible (curable) with appropriate treatment.

Initially, a simple laboratory test is performed, which can detect a number of diseases, not just metabolic diseases.

Routine tests include blood count, differential blood count, blood biochemistry (minerals, glycaemia, renal parameters, liver function tests, albumin, inflammatory markers, etc.), sediment and urine biochemistry, hormone profile especially thyroid hormones (TSH and fT4), vitamin B12 and folic acid levels and last but not least serological tests for syphilis infection.

In addition to these parameters, we can also examine the levels of other B vitamins and vitamin D from the blood, toxicological examination, the levels of some neurotoxic drugs, tests for the presence of HIV infection and borrelia, and determination of heavy metal levels, among others.

To diagnose vascular dementia, an examination of the cardiovascular system, i.e. the heart and blood vessels, is essential. Auxiliary examinations include ECG, Holter examination, ultrasound of the carotid vessels or chest X-ray.

The course of dementia depends on the location of the damage and atrophy of the brain, the age at which the patient first develops symptoms, and the concomitant diseases that may have triggered the dementia. Last but not least, it depends on the social conditions in which the patient has lived and the family members who will help him or her cope with the disease.

If the patient is affected by cortical dementia, the onset of the disease will be characterised by impaired memory, speech and intellect. The course is characterised by certain stages and is accompanied by other symptoms.

The first phase may be inconspicuous to the patient and others. Headache, dizziness, slight decrease in intellect, slowing of thinking and mild memory impairment are common.

Minor errors, such as counting and money errors, begin.

Difficulties with reading and speech are associated. Patients may often repeat words and sounds they hear. This is called echolalia.

In the first stage, there are no motor manifestations. Depression, restlessness and nervousness are more pronounced.

In the second stage, memory impairment is more pronounced, with cognitive impairment added.

Memory is affected, particularly in the area of forgetfulness of daily events. The patient has difficulty remembering where he has been, what he has done, what he had for lunch. He may forget where he has put various objects. He feels that he is losing them or putting them away in unusual places.

Orientation in space and time is also impaired. This is why people with dementia get lost in a familiar city, on a familiar street, not knowing what bus they are travelling on or where they are going. After such an experience, they are very upset and confused, which promotes deepening anxiety and depression.

The second stage lasts for 1-3 years, when family members, colleagues or the patient themselves notice the change in behaviour. This is why dementia is most often diagnosed at this stage.

In the next stage, the progression of cognitive impairment is very rapid.

In addition to impairments in remembering and learning, the old memory is also affected. Patients cannot remember their date of birth, address, where they live, do not recognise familiar places, people, family, partner, children, talk out of turn, and often mentally stray to illogical things.

There is also a deterioration of the psychological state, emotional instability, behavioural and thinking disorders. Poor sleep, disturbed sleep rhythms, frequent waking up at night, pacing around the room, even leaving the room or the home, place a great psychological burden on the family or guardian.

Patients are absolutely dependent on the care of another person.

The terminal stage of dementia is characterised by incapacity, immobility, incontinence, audible cries, aggressive attacks, and unpleasant behaviour and treatment, often of the body or excretions such as urine or faeces.

As it is a progressive neurodegenerative disease, the prognosis is not favourable. The survival of a patient diagnosed with dementia depends on many factors. The age of the patient and the rate of progression are important.

The most common cause of death in patients with end-stage dementia is aspiration pneumonia, a very difficult disease to manage in their condition.