Dementia is not a single specific disease but a general name for a collection of symptoms that can be caused by a variety disorders. These disorders are usually neurological conditions that involve damage to and loss of brain cells, or neurons.

People with dementia have problems with thinking, memory or reasoning that is severe enough to interfere with their ability to live independently and do normal daily tasks. Dementia can also sap people’s capacity to control their emotions and handle complex responsibilities, such as managing finances.

Getting older is the biggest risk factor for dementia, but it isn’t a normal part of the aging process, and many people live into their nineties without signs or symptoms of dementia. Read on to get the facts on causes, risk factors and more.

What are the symptoms of dementia?

There are many different forms of dementia, and its symptoms depend on the disorder that’s causing the dementia, as well as how advanced the dementia is.

Memory loss is a common symptom of dementia, but having memory loss by itself doesn’t mean someone has dementia. Mild problems with short-term memory can be part of normal aging and don’t cause major issues in daily life, as dementia does.

For a doctor to make a diagnosis of dementia, a person must have substantial problems in at least one area besides memory, such as in understanding written or spoken language or in reasoning and problem-solving skills.

People with dementia and their family and friends may also notice changes in personality, problems recognizing familiar people and places, agitation, and aggression.

Alzheimer’s disease is the most common cause of dementia among people older than 65. Early symptoms may be subtle and can include:

• Confusion
• Problems with speech or writing
• Difficulty concentrating and reasoning
• Problems with complex tasks, such as paying bills
• Getting lost in familiar places

Later symptoms can include: 

• Episodes of anger, hostility or aggressive behavior, though some people become more passive
• Hallucinations, delusions or both
• Disorientation
• Needing help with basic tasks such as eating, bathing and dressing
• Incontinence

How is dementia diagnosed?

Doctors will first take a complete medical history and do a physical and neurological exam to look for possible causes of dementia symptoms.

Doctors may also do other tests, including:

• Cognitive and neuropsychological tests that measure thinking, language, math and other skills linked to overall mental function.
• Lab tests, including a complete blood count, blood glucose, urinalysis and others, to rule out treatable problems that can cause symptoms of dementia.
• Brain scans using MRI (magnetic resonance imaging), CT (computed tomography) or PET (positron emission tomography).  

With some types of dementia, doctors can’t make a definite diagnosis until they can examine the brain after death, during an autopsy.

What causes dementia?

Many different brain diseases can cause dementia. These include:

• Vascular dementia, which can be caused by multiple small or large strokes
• Lewy body dementia
• Parkinson’s disease
• Huntington’s disease
• Frontotemporal dementia
• Creutzfeldt-Jakob disease

Dementia can also be caused by repeated damage to the brain – for example, head trauma from boxing or football or a long-term alcohol or drug habit.

Some conditions can cause dementia-like symptoms and episodes that usually are reversible with treatment. These include:

• Cerebral vasculitis that causes inflammation and death of blood vessel wall tissue
• Severe depression
• Medication side effects
• Infections, which can cause confusion and delirium
• Normal pressure hydrocephalus
• Metabolic disorders of the nervous system
• Thyroid problems
• Low blood sugar, or hypoglycemia
• Levels of calcium or sodium that are too high or too low
• Vitamin B1 (thiamine) or vitamin B12 deficiency

What are risk factors for dementia?

• Older age – the biggest risk factor for dementia, which is rare in people younger than 60, but affects to some degree up to half of those older than 85
• Alcoholism; long-term heavy drinking increases the risk of dementia
• Genetics
• Atherosclerosis
• High blood pressure
• Smoking
• Diabetes
• Down syndrome
• Benzodiazepine use by people older than 66

How is dementia treated?

The treatment of dementia depends on its underlying cause, as well as the specific symptoms individuals are experiencing.

There are drugs for Alzheimer’s disease called cholinesterase inhibitors, for example, aimed at temporarily stabilizing or improving memory. While these medications may work initially, though, they can eventually become ineffective as the disease progresses.

Drugs that control high blood pressure, high cholesterol and other factors that increase risk for stroke are often used to help prevent additional damage in people with vascular dementia.

Doctors can also use medications and other treatments, including psychotherapy, to address problems with behavior, depression, anxiety, agitation, irritability, aggression, and sleep.