What causes dementia?

What causes dementia?

What causes dementia?

Dementia is a neurodegenerative condition that describes the damage of the nerve cells of the brain, this can occur in a number of areas in the brain.

The condition affects people in different ways and each case is unique. The symptoms are dependent on the area of the brain that is affected.

Neurodegenerative’ refers to the gradual decline in the functioning of the nerve cells in the brain, also known as neurons, meaning that the neurons will gradually stop functioning correctly and perish. This results in an impact on the connections between the neurons, known as synapses, which refers to the communication of messages in the brain telling the body how to function. This disconnect often results in a number of dysfunctions.

There are a number of different types of dementia, the types are grouped by their similarities, such as their progressive traits or the part of the brain impacted. There are some dementias, for example, those that have been caused by an onset reaction to vitamin deficiencies or medications, these types are sometimes reversible and able to improve through treatment. Note that dementia is reversible in cases where the cause is alcohol, drugs, hormonal, medication or even depression. However, the condition is irreversible when the cause is that of trauma or a degenerative disease.

Progressive dementias

There are certain dementia types that are not reversible and progress over time, these include:

  • Alzheimer’s disease – Alzheimer’s disease is known to be the most prevalent cause of dementia in those who are 65 years old or older. The exact cause of Alzheimer’s disease is still unknown, however, those who are diagnosed with the condition, have tangles and plaques found in their brain. These are accumulations of abnormal proteins known as amyloid plaques. These fibrous tangles are made of abnormal tau proteins which cause microtubules, that facilitate the transport of vital chemicals and nutrients in the brain, to collapse, leading to damage of the nerve cells. Alzheimer’s usually occurs in patients over 65 years old, although some cases may even develop in patients who are just 40 or 50 years old. The condition is also known as Alzheimer’s dementia.
  • Vascular dementia – The second most well known cause or type of dementia is vascular dementia. It is the result of blood vessels supplying blood to the brain being damaged. Issues with the blood vessels can be the result of conditions regarding the blood vessels such as a stroke. Vascular dementia is often the case when a person has multiple strokes that go unnoticed as they do not show the typical symptoms of visions loss, numbness or weakness associated with a stroke. Patients who have heart disease or hypertension that is not treated, have a higher risk of vascular dementia developing.

Vascular Dementia

  • Lewy body dementia – Clumps of specific proteins in the brain that are abnormal are known as Lewy bodies, these are found in those who suffer from Lewy body dementia. These proteins accumulate inside the neurons in the brain. Memory issues and forgetfulness are signs of cognitive decline, these are some of the key features associated with this condition. Patients may also have prominent hallucinations, these hallucinations will seem very realistic to the person experiencing them. Some cases amongst those who suffer from Lewy body disease may also develop symptoms similar to those of Parkinson’s disease, these symptoms will be slowness or tremors. Lewy body disease is a common form of progressive dementia.
  • Frontotemporal dementia – There is a certain group of degenerative diseases that break down the nerve cells found in the temporal and frontal lobes of the brain, these areas are associated with the patient’s behaviour, personality and their language. Frontotemporal dementia is generally associated with shrinkage or pronounced atrophy of these lobes. These patients will experience forgetfulness as well as changes in their personality, poor judgment and even impulsivity. Some people with this form of dementia may even suffer from stiffness in their muscles or develop incoordination. The cause of frontotemporal dementia is still unknown.
  • Mixed dementia -  Autopsies done on the brains of those who are 80 years old or older, who suffer from dementia, show that many of these people had Lewy body dementia, Alzheimer’s disease and vascular dementia combined. There are still ongoing studies being conducted to figure out how suffering from mixed dementia affects the treatment and symptoms.

Other disorders that have been linked to dementia

  • Huntington's disease – This is a condition that is the result of a genetic mutation and causes specific nerve cells in the spinal cord and brain to progressively degenerate. The symptoms and signs of Huntington’s disease include a severe decline in the patient’s cognitive abilities, these symptoms typically show up around the ages of 30 and 40 years old.   
  • Traumatic injury to the brain – This is a condition that is the result of head traumas that are repetitive, these are normally experienced by football players, soldiers and boxers. The signs of dementia are dependent on the area of the brain that has been injured. Depression, memory loss, explosiveness, tremors, slow movement, and even rigidity (parkinsonism) have been known to develop. Symptoms may only appear years after the incident or brain injury.  
  • Creutzfeldt-Jakob disease – A rare brain disorder, it typically develops in those who do not have any risk factors that are known to be present. This disease may be the result of abnormal forms of protein within the brain or it can be inherited. This is a fatal condition and the symptoms and signs tend to appear when the patient is about 60 years old. The abnormal protein results in the destruction of the brain cells as well as dementia. Most of the cases appear without an exact cause. In very rare cases, the patient may have been exposed to an abnormal protein such as prions found in Mad cow disease – this is an exposure that is external. This disease normally progresses rapidly over a couple of years and tends to be associated with muscle movements that are abnormal.
  • Parkinson's disease – A lot of patients who suffer from this disease have been known to develop the symptoms of dementia, this is known as Parkinson's disease dementia.  Parkinson’s is a central nervous system disorder which affects the movement of the patient and often includes tremors.

Conditions that are similar to dementia that are able to be reversed

Some of the causes of symptoms that are similar to those of dementia and that are able to be reversed with treatment include:

  • Immune disorders and infections – Symptoms that are dementia-like may be a result of fever as well as other side effects of the body attempting to fight off possible infection. Multiple sclerosis is an example of a condition that results from the immune system attacking the nerve cells, the immune system basically eats away the protective nerve covering, this attack of the nerve cells is able to cause dementia.
  • Nutritional deficiencies – Being dehydrated in not drinking enough liquids, or not getting enough of the vitamins B-1, B-6 and B-12, are issues that are often experienced by those who have an addiction to alcohol, and as a result, may develop symptoms that are similar to dementia.
  • Subdural hematomas – These occur if there is bleeding between the covering of the brain and the surface of the brain, which is common when an elderly person falls, this can lead to symptoms similar to those of dementia.
  • Endocrine abnormalities and metabolic issues – People who suffer from issues with their thyroid, have low blood sugar, which is known as hypoglycaemia, have too much or too little calcium or sodium, or struggle to absorb the vitamin B-12, can often develop symptoms that are similar to those of dementia, along with changes to their personality.
  • Reactions to medications – Medication that causes a reaction or the interaction of several medications, may often result in symptoms of dementia.
  • Poisoning – Being exposed to lead, pesticides, and other heavy metals and poisons, as well as the abuse of recreational drugs and alcohol, can often result in dementia-like symptoms.
  • Brain tumours – In rare cases, dementia may be a result of damage from a brain tumour.
  • Anoxia – This is a condition, which is also known as hypoxia, that occurs due to the organ tissues not receiving enough oxygen. Anoxia can be a result of severe asthma, carbon monoxide poisoning, heart attack or other causes.  
  • Normal-pressure hydrocephalus – Also known as NPH, this is an accumulation of the cerebrospinal fluid, also known as CSF, which causes the enlargement of the ventricles in the brain that may cause walking issues, memory loss and urinary difficulties.
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