Aging & Health A to Z

Dementia

Causes & Symptoms

The causes of dementia include:

• Alzheimer’s disease, a brain disease that causes abnormal changes that kill brain cells
• Other diseases such as Parkinson’s disease, which affects movement and, later, mental abilities and mood.
• Blockages in blood vessels in the brain that limit blood flow to parts of the brain or trigger mini strokes. These cause a type of vascular dementia known as multi-infarct dementia.
• Serious head injuries
• Some brain tumors
• Heavy drinking for more than 10 years
• An overactive or underactive thyroid gland
• Insufficient Vitamin B₁₂
• Certain brain infections, including infection with HIV (the virus that causes Acquired Immunodeficiency Syndrome (AIDS))
• Exposure to certain drugs, and reactions to combinations of drugs
• The growth of abnormal structures in the brain called Lewy bodies, which cause a form of dementia called Lewy Body Dementia.
• The shrinking of certain parts of the brain, which causes a less common  form of dementia called frontotemporal dementia.

Dementia may have more than one cause. People who have Alzheimer’s disease, for example, often have vascular dementia too.

Alzheimer’s disease and vascular dementia are the most common forms of dementia in older adults. They are not curable. But they can be treated in ways that can improve functioning and quality of life and slow the rate at which symptoms get worse. Alzheimer’s disease accounts for nearly 70% of all cases of dementia. Vascular dementia accounts for more than 10%.  

Risk Factors for Dementia

A risk factor for a health problem is something that increases your risk, or likelihood, of developing that health problem. Simply having a risk factor does not mean you’ll develop the problem. It simply means that you have a higher risk of developing the problem than someone without the risk factor.  The risk factors of Alzheimer’s disease and vascular dementia are somewhat different.

Risk Factors for Alzheimer’s disease

• Age: While 6% to 8% of adults 65 and older have Alzheimer’s disease, nearly 30% of 85 year olds do.
• Family history: About half of those who have a parent or sibling with Alzheimer’s develop the disease by age 90.
• Depression
• Down Syndrome
• Serious head injury
• Fewer years of formal education
• Delirium

Risk factors for Vascular Dementia
Most risk factors for vascular dementia are the same as those for heart disease and stroke. These problems make it more likely that blockages will form in your blood vessels and limit or cut off blood flow and oxygen to your brain:

• High blood pressure 
• High levels of bad cholesterol (LDL) in your blood and low levels of good cholesterol (HDL)
• Age: Blood vessels stiffen and narrow as we grow older
• Smoking
• Diabetes 
• A family history of stroke or heart disease
• Obesity
• An inactive, sedentary lifestyle
• High stress levels

Visit the Prevention section to get easy-to-follow information about living a heart-healthy lifestyle.

Mild cognitive impairment (MCI) is a condition where people have problems with memory, language, and other mental abilities. These are noticeable and show up on medical tests, but don’t necessarily interfere with a person’s daily life. For that reason MCI isn’t considered a form of dementia. Although people diagnosed with MCI run an increased risk of developing dementia, but they don’t always.

Symptoms of Alzheimer’s Disease and Vascular Dementia

Alzheimer’s disease and vascular dementia are progressive disorders. This means that the changes in mental abilities, mood, personality, and the behavior they cause are gradual and tend to get worse over time. Exactly how quickly these dementias progress varies from person to person. The symptoms of vascular disease usually worsen when a person has another “mini-stroke” or develops a new blockage that limits blood flow to a specific part of the brain.

Memory loss is usually the first and most noticeable symptom of Alzheimer’s disease. With vascular dementia, symptoms depend on where a blockage forms. In addition to the most common symptoms, mini strokes (TIAs) and blockages may cause vision loss, hearing loss, and paralysis on one side of the body.

Common symptoms of Alzheimer’s disease and vascular dementia include increasing confusion and growing difficulty with:

Early on:

• Remembering. People with early Alzheimer’s disease may only occasionally have trouble remembering names, words, or where they put things.  This is different from advanced dementia, when the patient may no longer recognize people they are close to.
• Paying attention.
• Carrying out daily tasks such as shopping, cooking, or taking medications.
• Using and understanding language.  This is not as severe as advanced Alzheimer’s disease, where people may lose the ability to participate in conversation.
• Making decisions, planning, and getting organized.
• Finding their way from one once-familiar place to another.

Along with changes in mental abilities, people with Alzheimer’s disease or vascular dementia may exhibit “behavioral symptoms of dementia,” if they:

• Show changes in mood, such as becoming more agitated, anxious, or depressed.
• Seem drained of energy, or as though they don’t care.
• Undergo changes in behavior, such as becoming more aggressive or behaving inappropriately.  Aggressive behavior may range from cursing and spitting to physical attacks.
• Wander or ask to “go home” when they are home.
• Have hallucinations (seeing or hearing things that aren’t there) or delusions (false beliefs, such as the belief that a family member, friend, or caregiver is trying to hurt them or is stealing from them).

In general, the more severe the symptoms of dementia, the shorter a person’s life expectancy is likely to be. Wandering, falling, loss of bladder control, and behavioral problems such as agitation and hallucinations are linked to a shorter life expectancy.

Updated: September 2017
Posted:  March 2012