Dementia is a collective term used to describe various symptoms of cognitive decline, such as forgetfulness. It is a symptom of several underlying diseases and brain disorders.
Dementia is not a single disease in itself, but a general term to describe symptoms of impairment in memory, communication, and thinking.
While the likelihood of having dementia increases with age, it is not a normal part of aging.
An analysis of the most recent census estimates that 4.7 million people aged 65 years or older in the United States were living with Alzheimer’s disease in 2010. The Alzheimer’s Association estimates that:
just over a tenth of people aged 65 years or more have Alzheimer’s disease
this proportion rises to about a third of people aged 85 and older
Alzheimer’s accounts for 60-80 percent of all cases of dementia
This article discusses the potential causes of dementia, the various types, and any available treatments.
Fast facts on dementia
there are an estimated 47.5 million dementia sufferers worldwide
one new case of dementia is diagnosed every 4 seconds
dementia mostly affects older people but is not a normal part of aging
Dementia symptoms include memory loss, disorientation, and mood changes.
A person with dementia may show any of the symptoms listed below, mostly due to memory loss.
Some symptoms they may notice themselves, others may only be noticed by caregivers or healthcare workers.
The signs used to compile this list are published by the American Academy of Family Physicians (AAFP) in the journal American Family Physician.
Possible symptoms of dementia:
Recent memory loss – a sign of this might be asking the same question repeatedly.
Difficulty completing familiar tasks – for example, making a drink or cooking a meal.
Problems communicating – difficulty with language; forgetting simple words or using the wrong ones.
Disorientation – getting lost on a previously familiar street, for example.
Problems with abstract thinking – for instance, dealing with money.
Misplacing things – forgetting the location of everyday items such as keys, or wallets, for example.
Mood changes – sudden and unexplained changes in outlook or disposition.
Personality changes – perhaps becoming irritable, suspicious or fearful.
Loss of initiative – showing less interest in starting something or going somewhere.
As the patient ages, late-stage dementia symptoms tend to worsen.
Sometimes, dementia is roughly split into four stages:
Mild cognitive impairment: characterized by general forgetfulness. This affects many people as they age but it only progresses to dementia for some.
Mild dementia: people with mild dementia will experience cognitive impairments that occasionally impact their daily life. Symptoms include memory loss, confusion, personality changes, getting lost, and difficulty in planning and carrying out tasks.
Moderate dementia: daily life becomes more challenging, and the individual may need more help. Symptoms are similar to mild dementia but increased. Individuals may need help getting dressed and combing their hair. They may also show significant changes in personality; for instance, becoming suspicious or agitated for no reason. There are also likely to be sleep disturbances.
Severe dementia: at this stage, symptoms have worsened considerably. There may be a loss of ability to communicate, and the individual might need full-time care. Simple tasks, such as sitting and holding one’s head up become impossible. Bladder control may be lost.
There are several types of dementia, including:
Alzheimer’s disease is characterized by “plaques” between the dying cells in the brain and “tangles” within the cells (both are due to protein abnormalities). The brain tissue in a person with Alzheimer’s has progressively fewer nerve cells and connections, and the total brain size shrinks.
Dementia with Lewy bodies is a neurodegenerative condition linked to abnormal structures in the brain. The brain changes involve a protein called alpha-synuclein.
Mixed dementia refers to a diagnosis of two or three types occurring together. For instance, a person may show both Alzheimer’s disease and vascular dementia at the same time.
Parkinson’s disease is also marked by the presence of Lewy bodies. Although Parkinson’s is often considered a disorder of movement, it can also lead to dementia symptoms.
Huntington’s disease is characterized by specific types of uncontrolled movements but also includes dementia.
Other disorders leading to symptoms of dementia include:
Frontotemporal dementia also known as Pick’s disease.
Normal pressure hydrocephalus when excess cerebrospinal fluid accumulates in the brain.
Posterior cortical atrophy resembles changes seen in Alzheimer’s disease but in a different part of the brain.
Down syndrome increases the likelihood of young-onset Alzheimer’s.
Early signs of dementia can include:
Changes in short-term memory.
Changes in mood.
Trouble finding the right words.
Finds it hard to follow a storyline.
Trouble completing everyday tasks.
Poor sense of direction.
Difficulty adapting to changes.
Dementias can be caused by brain cell death, and neurodegenerative disease – progressive brain cell death that happens over time – is associated with most dementias.
However it is not known if the dementia causes the brain cell death, or the brain cell death causes the dementia.