Generality
Dementias are neurodegenerative diseases of the brain, which usually occur in old age (but there are exceptions) resulting in a progressive decline of a person's cognitive faculties.
The causes of dementia have not yet been fully clarified. At the moment, the only certainty is that, to cause its onset, are the death of brain nerve cells and / or their malfunctioning at the level of intercellular communication.
The demented can manifest a wide range of symptoms and signs; these vary depending on the area of the brain affected.
Unfortunately, many forms of dementia are incurable. In fact, there is still no treatment that can reverse or at least halt the neurodegeneration process for which they are responsible.
What is dementia?
Dementia is the medical term used to indicate a group of neurodegenerative diseases of the brain, typical of old age (but not exclusive to the elderly), which involve the gradual, and almost always irreversible, reduction of a person's intellectual faculties.
CLASSIFICATION OF DEMENTIA
Since there are so many different types of dementia, doctors who are experts in neurodegenerative diseases have long discussed what could be the best way to classify them.
Today, the possible classifications are more than one and they always have, as a parameter of distinction, a common general characteristic, such as:
- The brain area affected by neurodegeneration (NB: neurodegeneration means a process that leads to the progressive loss of neurons).
According to this parameter, dementias are distinguished into cortical and subcortical (or subcortical).
Cortical dementias are those that arise as a result of damage to the cerebral cortex, ie the outermost laminar layer of the brain.
Subcortical dementias are those that appear after a deterioration of the brain portion located under the cerebral cortex.
- The reversibility or non-reversibility of dementia .
According to this parameter, dementias are distinguished into reversible and irreversible.
Reversible dementias are those for which there is a possibility of healing or, at least, of regression of symptoms. There are few with these characteristics and they are often associated with morbid conditions that affect other organs or systems.
Irreversible dementias are incurable and tend to worsen gradually and inexorably (in fact, they are also called progressive). Unfortunately, they represent the majority of dementias.
- Dependence or not on other morbid states .
According to this distinctive parameter, dementias are divided into primary and secondary.
Primary dementias are those that do not derive from any other morbid state.
The secondary dementias are those that appear subsequently to other pathologies, from the neurological character (for example, the amyotrophic lateral sclerosis or the Parkinson's disease), traumatic (for example, after repeated blows to the head) or of still other kind (vascular, infectious etc).
TYPES OF DEMENTIA
As previously stated, the types of dementia are numerous. Here is a list of the most important:
- Alzheimer's disease
- Vascular dementia
- Dementia with Lewy bodies
- Frontotemporal dementia
- Boxing dementia
- Dementia associated with HIV
- Huntington's disease
- Corticobasal degeneration
- Creutzfeldt-Jakob disease
- Gerstmann-Sträussler-Scheinker syndrome
Taking Alzheimer's disease as an example - the most well-known form of dementia - this disease can be classified as a cortical, irreversible and primary dementia.
DEPARTURES OF CHILDREN
Dementias do not only affect adults.
In fact, some exist exclusively for children ( childhood dementias ).
These neurodegenerative diseases are very rare and dependent on the presence of an inherited mutation at the level of some fundamental genes.
Among the various known childhood dementias, the best known are: Niemann-Pick 's disease, Batten 's disease and Lafora's disease (or Lafora's bodies).
THE NON-DEATHS
Doctors are keen to point out that, although they determine the same symptoms, the following conditions should not be considered dementia:
- Cognitive decline related to advanced age .
As the human being ages, his brain undergoes a normal process of involution. In fact, it slowly reduces its volume, loses several neurons and no longer efficiently transmits nerve signals.
- Mild cognitive impairment (or impairment) .
Characterized by a less profound neurodegeneration than dementia, it very often anticipates the latter.
- Depression as a psychiatric disorder .
In the depressed, the disorders are not due to a degeneration of the brain; in fact, the nervous scaffolding is intact.
- The delirium .
It is a psychiatric disorder, sometimes induced by taking certain drugs, but still treatable.
Epidemiology
According to a US statistic of 2010, there are about 36 million people in the world suffering from dementia: of all these individuals, 3% are between 65 and 74, 19% between 75 and 84 and more than half have from 85 years upwards.
Most of the world's demented (50-70%) are affected by Alzheimer's disease (the most common form of dementia in humans), 25% by vascular dementia, 15% by dementia with Lewy bodies and the remaining percentage from other known forms of dementia.
In Italy, people with dementia are between 1 and 5% of people over the age of 65 and 30% of individuals over the age of 80.
Given the continuous increase in average life, the experts predict that in 2020 the world's subjects with a form of dementia will be around 48 million.
Causes
The causes of dementia have not yet been established with certainty and clearly. Moreover, the human brain is a highly complex and difficult to study structure.
The only certain data, relating to the triggers, is that any type of dementia is the result of two events: the death of brain nerve cells and / or their malfunction at the level of intercellular communication (ie between cell and cell).
DEMENTIA AND PROTEIN AGGREGATES IN THE BRAIN
Different forms of dementia - including Alzheimer's disease, dementia with Lewy bodies and frontotemporal dementia - are characterized by the presence, outside and / or inside the brain neurons, of anomalous protein aggregates (also called inclusions ) .
Some of the proteins involved in these abnormal formations are the so-called beta-amyloid precursor protein (APP), the so-called tau protein and alpha-synuclein .
- APP forms amyloid plaques ; these interpose between neuron and neuron and are typical presences of Alzheimer's disease.
- The tau protein gives rise to neurofibrillary tangles and other similar structures ; these, unlike amyloid plaques, develop inside neurons (in the cytoplasm) and can be found in Alzheimer's patients, frontotemporal dementia and corticobasal degeneration.
- Finally, the alpha-synuclein generates insoluble agglomerates inside the cytoplasm called Lewy bodies ; the latter are characteristic of dementia with Lewy bodies, but are also found in people with Parkinson's disease or multisystem atrophy.
Despite numerous studies conducted, researchers have not yet clarified the precise mechanism by which protein aggregates cause the progressive deterioration of the affected brain tissue. They only know that:
- Post-mortem examination of patients' brain tissue reveals abnormal agglomerates.
- In brain healthy people, APP, tau and alpha-synuclein do not form dangerous agglomerates or at least, if they form them, they grow very slowly and a natural defense mechanism intervenes that eliminates them.
Dementia, protein aggregates and genetics
Sometimes, the protein inclusions are the result of genetic mutations present since birth, inherited from one of the two parents.
For example, the alterations of PSEN1 and PSEN2 - the genes for presenilin 1 and 2 - are responsible for a juvenile form of Alzheimer's disease, which occurs around 30-40 years.
Another example is that of the MAPT genes for the tau protein and the GRN and C9ORF72 genes for the TDP-43 protein: their hereditary mutation causes frontotemporal dementia.
OTHER SPECIAL CONDITIONS LINKED TO THE DEEDS
According to reliable studies, in fact:
- Vascular dementia is linked to cerebrovascular problems, or disorders that prevent the normal flow of blood into the tissues of the brain. After all, the blood carries with it oxygen and nutrients, fundamental elements for the life of any cell in the body.
Some of the most influential cerebrovascular problems are: the so-called small blood vessel disease, atherosclerosis in the brain and stroke.
- Creutzfeldt-Jacob disease and Gerstmann-Sträussler-Scheinker syndrome are related to the change of a protein called prion .
When even just one prion molecule changes, it becomes a contaminating agent for all the others, which undergo the same alterations. All this ends with the progressive deterioration of the brain nerve cells.
- Huntington's disease (also called Huntington's) arises as a result of an inherited mutation in the gene that produces the huntingtin protein . People with this mutation report the first signs of dementia around 30-40 years and can survive, even before death, for up to 15 years.
- Boxing dementia, also known as chronic traumatic encephalopathy, appears after repeated head injuries . It is typical of those who once practiced boxing (that's where the name comes from), American football, wrestling or rugby, or all contact sports during which it is common to receive headshots.
- Dementia associated with HIV is, as the name implies, following AIDS virus infection. This particular neurodegenerative disease, which affects the cerebral white matter, does not occur in all HIV patients, but only in some. Scholars are trying to understand the reason for this double behavior.
RISK FACTORS
The numerous studies conducted on dementias have led to the identification of some risk factors.
A risk factor (or favoring factor) is a particular condition that predisposes to a certain disorder or disease, but that does not properly represent the cause.
Among the factors favoring dementias, they can be recognized as modifiable and not modifiable .
The modifiable ones are hypercholesterolemia (ie high cholesterol), atherosclerosis, cigarette smoking, high levels of homocysteine in the blood, alcohol abuse and diabetes.
The non-modifiable risk factors, however, are advanced age, the recurrence within the same family of a given form of dementia, being suffering from Down syndrome and mild cognitive decline.
Symptoms and Complications
Premise: each area of our brain (set of proper brain, diencephalon, cerebellum and brainstem) controls a specific function.
For example, in the brain, the occipital lobes are responsible for processing vision; the temporal lobes control part of memory capacity, spoken language, understanding of sounds, affective behaviors and those related to relationship life; the frontal lobes provide learning, some memory skills, the formulation of ideas and thoughts, etc.
The symptoms and signs of dementia vary depending on the area of brain subject to neurodegeneration. Therefore, the symptomatic picture manifested by a demented can include a high number of cognitive disorders.
Overall, people with dementia suffer from:
- Amnesia . Memory loss is one of the most common problems; represents one of the first symptoms that arise in Alzheimer's patients.
- Concentration, planning and reasoning deficits; slowness of thought . These disorders are first noticed by relatives, who realize that the patient cannot concentrate even on reading very simple texts or on simple mathematical calculations.
- Difficulty making decisions and performing simple daily tasks (for example, using a coffee stain, a microwave oven, etc.).
- Mood swings, abnormal behavior and personality changes . Patients tend to switch easily from euphoria to depression, to become irritable and / or impulsive, to become more agitated and anxious, etc.
- Language difficulties . These include the inability to finish conversations and to call objects with the correct names, the tendency to repeat sentences pronounced by others, the use of a reduced vocabulary and a limited number of sentences.
- Visual problems . Among these, we recall the difficulties in reading, quantifying the distance of objects and determining exactly the colors. Moreover, in dementia such as Alzheimer's disease, a curious disorder arises, so patients, looking in the mirror, do not recognize themselves.
- Space-time confusion (or disorientation) . The demented in this state struggle (or just can't) to realize where they are, what day of the week it is or what the current season is. Moreover, they are often disoriented, so they ignore why they went to a certain place.
- Reduction or loss of judgment . This leads to a decrease in inhibitory brakes in many dementia sufferers, a tendency to act in an incorrect or abnormal manner (for example, unnecessary expenses and / or inappropriate attitudes in public), a certain lack of interest in personal hygiene, etc.
- Balance and / or movement problems
- Agitation attacks and hallucinations
Do dementias alter the state of consciousness?
Contrary to what is commonly thought, the state of consciousness of people with dementia remains unchanged. The demented, in fact, are subjects that, even in their own way, respond to verbal, tactile and painful stimuli.
EVOLUTION OF DEPARTURES
As mentioned above, many dementias have a progressive course : they begin with a slight symptomatology and, within a more or less long time, they lead to a marked deterioration of cognitive abilities.
Death from dementia often occurs due to a complication linked to dementia itself. For example, in the final stages, Alzheimer's disease leads to serious swallowing difficulties, which in turn lead to the development of recurrent inhalation pneumonias and serious nutrition problems.
DURATION OF THE DECLINE
The duration of cognitive decline is different from dementia to dementia.
For example, Alzheimer's disease usually takes 7-10 years to completely impair cognitive faculties; after which it causes death.
Vascular dementia or frontotemporal dementia, on the other hand, act differently from patient to patient: there are cases in which neurodegeneration proceeds very slowly and cases in which the deterioration of nerve cells is very rapid.
Diagnosis
The diagnostic evaluations include:
- Analysis of the patient's clinical history
- A thorough physical examination
- A complete neurological examination
- A cognitive and neuropsychological examination
- Nuclear magnetic resonance (NMR) and computerized axial tomography (CT), both referred to the brain
- Laboratory tests
ANALYSIS OF CLINICAL HISTORY
The analysis of clinical history is a medical investigation aimed at clarifying how and when the first disorders appeared, if the patient suffers or has suffered in the past from particular pathologies, if he uses certain drugs, if he has relatives suffering from dementia and so on.
Often, the patient's relatives also participate in this evaluation, as they can provide additional information
Although it is not sufficient for a final diagnosis, the analysis of clinical history can be very useful to exclude pathologies with symptoms similar to dementia.
ACCURATE OBJECTIVE EXAM
The physical examination involves the analysis of symptoms and signs, reported or manifested by the patient. Although it does not provide any certain data, it nevertheless represents an obligatory step, as it serves the doctors to ascertain the current disturbances.
NEUROLOGICAL EXAMINATION AND COGNITIVE EVALUATION - NEUROPSYCHOLOGICAL
The neurological examination consists of an analysis of tendon reflexes, motor skills (balance, etc.) and sensory functions.
Cognitive and neuropsychological evaluation, on the other hand, involves the study of behavior, memory skills, language skills and the faculty of reasoning.
Both tests can provide many useful information: for example, an Alzheimer's patient has specific memory and language problems and a particular difficulty with mathematical reasoning.
MRI AND TACS OF THE ENTENCE
Painless and with a total duration of 30-40 minutes, MRI and CT scan of the brain are two imaging diagnostic procedures useful in many cases, because they allow to observe:
- The process of degenerative atrophy (generalized or limited to certain sectors) of the cerebral cortex - a typical process of many forms of dementia - and the subsequent expansion of the so-called cerebral ventricles .
- The presence of cerebrovascular alterations (stroke, transient ischemic attack or mini-stroke), typical of vascular dementia.
- The presence of subdural hematomas, which, in some cases, are responsible for reversible dementia.
What are MRIs and CT scans?
MRI allows to visualize the internal structures of the human body, using an instrument that generates magnetic fields. In fact, in contact with the patient, these magnetic fields "emit signals" that are transformed into images by a special detector.
Sometimes, to improve the quality of the visualizations, the doctors take advantage of a contrast medium: in these situations, while not involving any kind of pain, the MRI becomes a minimally invasive examination.
The TAC, on the other hand, works in a totally different way: it uses ionizing radiation (or X-rays) to create a highly detailed three-dimensional image of the internal organs of the body.Also in this case, if you want to improve the quality of the display, you can use a contrast medium.
Regardless of the use of contrast media, exposure of the patient to X-rays makes the CT scan an invasive procedure.
LABORATORY EXAMINATIONS
The laboratory tests, which are carried out in case of suspected dementia, are very numerous.
Typically, they consist of:
- Blood tests
- Blood glucose measurement
- Urine analysis
- Toxicological tests
- Cerebrospinal fluid analysis
- Measurement of thyroid hormones
Their execution is very important, especially from the point of view of the differential diagnosis : toxicological tests, for example, make it possible to exclude that the symptoms are due to the abuse of drugs or alcohol; in the same way, blood tests allow to reject the hypothesis that the disorders are related to a deficiency of vitamin B1 (or thiamine).
GENETIC TESTS
Family members in whom particular forms of dementia occur (for example juvenile Alzheimer's or some subtypes of frontotemporal dementia) can undergo a particular genetic test, which will tell them if they are carriers of the responsible mutations or not.
In other words, they can find out if they have inherited a mutated gene from either parent.
Treatment
At present, many dementias (including Alzheimer's disease, vascular dementia and dementia with Lewy bodies) remain incurable, since a treatment capable of arresting neurodegeneration and reversing its consequences has not yet been discovered.
The only benefits that currently available therapies can provide are at a symptomatic level. In fact, the drugs administered in the event of dementia, physiotherapy, behavior therapy, occupational therapy, language therapy and cognitive stimulation serve only to improve the symptomatology .
For those interested in learning about the symptomatic treatments provided in case of Alzheimer's, vascular dementia and frontotemporal dementia, it is advisable to consult the following references: care for Alzheimer's, treatment for vascular dementia and treatment for frontotemporal dementia.
Prevention
Several studies have shown that, if one acts on reversible risk factors and if one adheres to certain behaviors, it is possible to prevent or at least postpone the onset of dementia.
Among the behaviors that proved to be effective at the preventive level, we recall:
- Learn a second language or play a musical instrument;
- Maintain the brain in practice, reading books or newspapers or dabbing in crosswords, puzzles or board games;
- Keep moving. In addition to positively affecting health, exercise promotes the production of a nerve growth factor (the so-called brain neurotrophic factor), which protects brain neurons from deterioration;
- Learn to control stress, which working and / or affective life can cause.
Prognosis
A progressive dementia can only have a negative prognosis; after all it is an incurable disease that sooner or later leads to an increasingly marked deterioration of cognitive functions.
Conversely, a reversible dementia can also have a positive prognosis, provided, however, that it is treated in time.
