Dementia is a decline in cognitive function. To be considered dementia, mental impairment must affect at least two brain functions. Dementia may affect:
Dementia is not a disease. It may be caused by a variety of illnesses or injuries. Mental impairment may range from mild to severe. It may also cause personality changes. Some dementias are progressive. This means they get worse over time. Some dementias are treatable or even reversible. Some experts restrict the term dementia to irreversible mental deterioration.
There are many causes of dementia. In general, it results from the degeneration of neurons (brain cells) or disturbances in other body systems that affect how neurons function.
Neurodegenerative means that neurons gradually cease to function or function inappropriately and eventually die. This impacts the neuron-to-neuron connections, called synapses, which are how messages are passed along in your brain. This disconnect can result in a range of dysfunction.
Some of the more common causes of dementia include:
People with dementia have declines in brain function that are significant enough to interfere with their relationships and daily routine. Doctors diagnose dementia when two or more functions are affected, such as memory and judgment. Many disorders can cause dementia. Some can be reversed, but others progress.
Other causes of dementia
Dementia may also be caused by other conditions, including:
- structural brain disorders, such as normal-pressure hydrocephalus and subdural hematoma
- metabolic disorders, such as hypothyroidism, vitamin B-12 deficiency, and kidney and liver disorders
- toxins, such as lead
Some of these dementias may be reversible. This is one of the many reasons why it’s important to see your doctor and get a medical workup as soon as symptoms develop.
It’s absolutely normal to forget things once in a while. Memory loss by itself does not mean you have dementia. There is a difference between occasional forgetfulness and forgetfulness that is cause for serious concern.
Potential red flags for dementia include:
- forgetting who someone is
- forgetting how to do common tasks, such as how to use the telephone or find your way home
- inability to comprehend or retain information that has been clearly provided
Seek medical attention if you experience any of the above.
Getting lost in familiar settings is often one of the first signs of dementia. For example, you might have trouble driving to the supermarket.
The number of people diagnosed with dementia or living with it is increasing. This increase is due partly to increasing life expectancy. By 2030, the size of the population 65 years of age and older in the United States is expected to almost double from 37 million people in 2006 to an estimated 71.5 million by 2030, according to the Federal Interagency Forum on Aging-Related Statistics Older Americans.
Scientists all over the world are working hard to gain a better understanding of the many different aspects of dementia. This might help to develop preventive measures, improved early detection diagnostic tools, better and longer-lasting treatments, and even cures.
For example, a vaccine known as a bapineuzumab jab is currently in its final phase of testing. Though it cannot cure dementia or related disorders, this vaccine has been shown to prevent the buildup of amyloid plaques in the brain. In some cases, this vaccine can even reverse buildup of these plaques. Amyloid plaques are the hallmark of Alzheimer’s disease. They’re mostly insoluble clumps of protein fragments that deposit a highly damaging gunky substance outside and around the brain’s nerve cells.
Scientists are investigating a variety of factors they think might influence the development of dementia, including:
- genetic factors
- various neurotransmitters
- factors that influence programmed cell death in the brain
- tau, a protein found in neurons of the central nervous system
- oxidative stress, or chemical reactions that can damage proteins, DNA, and lipids inside cells
This research can help doctors and scientists better understand what causes dementia, and then discover how best to treat and possibly prevent the disorder.
There is also increasing evidence that lifestyle factors may be effective in decreasing the risk of developing dementia. Such factors might include getting regular exercise and maintaining social connections.
Written by: Wendy Leonard, MPH
Medically reviewed on Nov 16, 2016 by Timothy J. Legg, PhD, CRNP