Dementia is a term used to describe a collection of symptoms caused by a number of disorders that affect the brain

People who live with dementia experience a progressive deterioration in their thought processes that interfere with their daily activities and relationships. They may experience difficulties in problem solving and maintaining emotional control, as well as changes in personality and behavioural problems.

Some of the diseases that can cause such symptoms are Alzheimer’s disease, vascular dementia, Lewy body dementia and frontotemporal dementia.

Other conditions can cause dementia or manifest similar symptoms such as reactions to medications, metabolic problems, endocrine abnormalities, nutritional deficiencies, infections, poisoning, brain tumours, anoxia or hypoxia (conditions in which the brain’s oxygen supply is either reduced or cut off entirely), and heart and lung problems.

Despite being more common among the elderly, dementia is not a normal part of the ageing process.

Alzheimer’s disease

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In more than half of all cases, Alzheimer's disease, first described by Alois Alzheimer in 1906, is the most common cause of dementia. It destroys brain cells and nerves disrupting the transmitters which carry messages in the brain, particularly those responsible for storing memories.

Alzheimer's is a progressive disease, which gradually, over time, damages more and more parts of the brain, thus making the symptoms more severe as it evolves.

In the initial phases of Alzheimer’s disease, it can manifest itself as memory lapses, difficulty in finding the right words to express oneself and to describe everyday objects. As it evolves, the person may begin to forget people’s names and recent events and may experience changes in their personality often becoming apathetic. They often feel confused in everyday situations and, in more advances stages of the disease, may adopt alarming behaviour such as wandering in the middle of the night or may adopt unsuitable behaviour.

Although there are some symptoms common to most cases of Alzheimer’s, it is important to remember that each person is unique and therefore may experience the disease quite differently.

Alzheimer's disease is considered the most common cause of dementia.

Vascular dementia

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Vascular dementia is a type of dementia caused by reduced oxygen flow to the brain causing a series of strokes, often so small that symptoms may not be noticed other than mild confusion, which cut off the blood supply causing brain cells to die. Over time, the damage caused by these strokes is often sufficient to cause vascular dementia.

As with many types of dementia, vascular dementia affects people in different ways, its progression varying from person to person. Some symptoms may be similar to those of other types of dementia however, vascular dementia is associated with difficulties in communication and concentration, depression, stroke-like symptoms such as paralysis, epileptic fits and so on.

Vascular dementia is one of the most common forms of dementia, ranking only second to Alzheimer’s disease.

Dementia with Lewy bodies

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Dementia with Lewy bodies (DLB) is a progressive and neurodegenerative disease. DLB, also known as Lewy body disease, is the second most frequent cause of age-related neurodegenerative dementia. DLB owes its name to smooth round protein structures called Lewy bodies found in the nerve cells in the outer layer of the brain. Due to DLB sharing similar symptomatology with Alzheimer’s or Parkinson’s disease, down syndrome and other diseases, in 1995 there was a consensus among international researchers to use the term “Dementia with Lewy bodies” to describe a specific disease (sometimes referred to as “Pure Dementia with Lewy bodies”) as well as a range of disorders with similar or related pathology.

As well as a the behavioural and memory symptoms characteristic of dementia, people with DLB can also show neuromuscular symptoms similar to Alzheimer’s and Parkinsons disease, such as cognitive disorders, shaking, muscular stiffness and shuffling gait. They may also experience visual hallucinations.

The causes of DLB remain unknown and no specific risk factors have been identified. Despite a number of families experiencing multiple cases of the disease no genetic link has been found.

Dementia with Lewy bodies is the third most common cause of dementia.

Frontotemporal dementia

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Frontotemporal dementia is a less common type of dementia, causing damage to the frontal lobe and/or the temporal parts of the brain.

In frontotemporal dementia, damage to the brain, even in more advanced stages, is confined to the frontal lobe and/or the temporal parts of the brain. Clinical manifestations of this type of dementia are almost exclusively cognitive, in that people may experience strong mood swings, changes in their personality, become apathetic to things that used to be of personal interest, they may show affective symptoms (depression, anxiety), experience disordered social conduct and altered judgement and become extrovert.

As other parts of the brain are not directly affected, the person rarely shows neurological changes, altered mobility, memory loss nor special orientation or difficulty in carrying out activities.

Typically, frontotemporal dementia progresses gradually with changes in social conduct and in the person’s level of impulsiveness. For this reason, diagnosis can be difficult as it is often mistaken for psychosis.