As many as one percent of people age 60 suffer from dementia, and the frequency of dementia has been estimated to double every five years thereafter. Dementia isn't a specific disease; it's a group of symptoms. To be diagnosed with dementia requires more than just memory loss. People with dementia have attention, orientation, memory, judgment, language, motor and spatial skills, and function defects severe enough to seriously affect their daily lives. Some of the most common causes of dementia are Alzheimer's disease, vascular dementia (damage to the blood vessels leading to the brain), brain injury, and brain tumors.

There are several marked differences between memory loss associated with aging and dementia. With normal aging, you're consciously aware when you can't remember something. You can also compensate for the loss of a word by substituting the idea with a similar concept. The person who has dementia may not be aware of these problems even when it is severe enough to change a person's mood and personality. Vascular dementia occurs when blood flow to the brain is interrupted for any reason and is sometimes called multi-infarct dementia. Brain cells can die from lack of oxygen, causing symptoms such as muscle weakness, speech difficulties, and other mental disturbances. Vascular dementia is the second-leading cause of dementia after Alzheimer's.

Whether it's small blockages (strokes or mini-strokes) or just severe blood vessel disease, when blood and nutrients can't get to the brain, cognitive impairment occurs. A person with dementia should be under a doctor's care. For some people in the early and middle stages of Alzheimer's disease, certain medications can be prescribed to possibly delay the worsening of some of the disease's symptoms. See a healthcare professional for a full evaluation if you notice one or more of these signs of dementia in yourself or a loved one:

• Recent memory loss: Many of the problems associated with dementia are caused by memory loss. Everyone forgets things for a while and then remembers them later. People with dementia often forget things, but they never remember them. They not only forget an object but also the context surrounding that object.
• Difficulty performing familiar tasks: People with dementia may forget how to cook a meal that they've prepared multiple times. They may have problems with dressing, color coordinating, and personal hygiene (all routines in the past).
• Problems with language: Folks suffering from dementia may forget simple words or use the wrong words or even add unusual words. This often makes conversations hard to follow.
• Time and place disorientation: People who have dementia get lost often. They can drive away, forget where they're going, and then get lost trying to return home. Some get confused whether it's night or day.
• Problems with abstract thinking: Dementia sufferers may forget what numbers are and what has to be done with them.
• Misplacing things: Some people may put things in the wrong places. Often they're trying to hide objects and then forget where they hid them. Hiding objects is a response to feeling the loss of control and insecurity based on memory loss. As the disease progresses, they have difficulty remembering who they know and who they can trust. They don't realize that this hiding things to "keep them safe" may backfire when they can't remember where they hid them - or even that they hid them.
• Changes in mood: People with dementia may have fast mood swings and can cover many in a short period. Some folks can become very angry, sad, and then seem happier than ever.
• Personality changes: These folks may become irritable, suspicious, or fearful.
• Loss of initiative: People who have dementia may become passive and don't like to go places.

Alzheimer's disease is a specific form of dementia that currently affects more than 5 million Americans, most over age 65. Twenty percent of dementia cases are diagnosed as Alzheimer's, which first appears between the ages of 40 and 60 in some people and affects only 10 percent of people in their 60s, but affects nearly 50 percent of those in their 80s. Alzheimer's gradually destroys a person's memory and ability to learn, reason, make judgments, communicate, and carry out daily activities. As Alzheimer's progresses, individuals may also experience changes in personality and behavior, such as anxiety, suspiciousness or agitation, as well as delusions or hallucinations. Currently, there's no cure for Alzheimer's, although a few drug treatments slow progression in some people. Alzheimer's causes a buildup of extracellular plaque in the brain, neuron loss in the cerebral cortex and deep cerebral regions, and brain atrophy. An abnormal collection of a protein called amyloid is found in the areas of the brain crucial to learning, memory, and maintaining a sense of time. A Canadian study done in 2002 showed that Alzheimer's was frequently preceded by a decline in verbal memory one to two years before the disease became obvious, so it's important for a person to be tested for Alzheimer's disease early in the disease process. That testing can help in early identification and treatment of potential Alzheimer patients. Alzheimer's can be difficult to diagnose, especially in its early stages; it is not just a more severe form of dementia. The diagnosis of Alzheimer's disease not only requires memory deficits but also another cognitive deficit, such as language disturbance. Sometimes it can be hard to tell the difference between normal age-related changes and signs of one of the brain diseases.

Parkinson's is a progressive, degenerative brain disease caused by the loss of dopamine-producing brain cells. The part of the brain where these nerve cells are located, the substantia nigra, is responsible for controlling muscle movement. Normally these nerve cells release dopamine, a neurotransmitter that signals other parts of the brain to coordinate muscle to make controlled movements. Loss of these nerve cells leads to difficulty with muscle movements.

Everyone will experience some loss of these dopamine-releasing nerve cells, but people with Parkinson's lose more than 50 percent of their cells. Parkinson's causes tremor, muscle rigidity that results in a "mask-like" facial expression, postural instability, and bradykinesia (slow movements). Depression, emotional changes, and difficulty swallowing and speaking are also common symptoms. This is a progressive, disabling disease, but many people have many quality years of life after diagnosis. Much research has been done on the cause of Parkinson's; it's believed to be a combination of genetic and environmental factors. Some medications and other diseases can cause Parkinson's-like symptoms in people who don't have the disease. There's a familial link for the disease, although it's a weak link.

Huntington's disease (HD), first described by Dr. Huntington in 1872, is still a disease with many unknowns. This genetic disease is a progressive, neurologic disease that unfortunately doesn't show symptoms until you're in your late 30s or older. In HD, a reduction in the amount of the neurotransmitters acetylcholine and GABA affects the amount of dopamine in the brain. The increased amounts of dopamine and the muscle movements are the opposite of Parkinson's, where there's a deficiency of dopamine. The initial symptoms start with clumsiness and then develop into strange posturing and uncontrollable movements. Most HD patients also develop progressive dementia and memory loss. HD is usually fatal within 15 to 20 years after symptoms begin. Death is a result of disabilities, such as swallowing, which can lead to choking, or by secondary infection from a impaired immune system. HD is a genetic disease caused by a dominant gene (a genetic trait is considered dominant when the disease is present in a person who has only one copy of that gene, received from one parent) which means that anyone that receives the gene from either parent will develop the disease.