Alzheimer’s Disease (AD) is a progressive, degenerative disorder of the brain that destroys memory and other mental functions such as thinking and language skills, concentration, orientation, judgment, social skills and the ability to perform normal daily living tasks.
Unlike Alzheimer’s, dementia is not a specific disease. It is a general term that describes a wide range of disorders and symptoms associated with a decline in memory and other thinking skills such as concentration, orientation, language, judgment and motor skills. Alzheimer’s is the most common cause of dementia, but several other conditions can result in dementia. Some types of dementia, like Alzheimer’s, are irreversible. There are as other conditions that can cause dementia-like symptoms, but may be treatable or even reversible. More information on other types of dementia may be found below.
According to the Mayo Clinic, scientists believe that for most people, AD results from a combination of genetic, lifestyle and environmental factors that affect the brain over time. Less than five percent of the time, AD is caused by specific genetic changes that virtually guarantee a person will develop the disease. Although the causes are not yet fully understood, AD damages and kills brain cells. When doctors examine AD brain tissue under a microscope, they see two types of abnormalities that are considered hallmarks of the disease:
Plaques. These clumps of a protein called beta-amyloid may damage and destroy brain cells in several ways, including interfering with cell-to-cell communication. Although the ultimate cause of brain-cell death is Alzheimer’s isn’t known, the collection of beta-amyloid on the outside of the brain cells is a prime suspect.
Tangles. Brain cells depend on an internal support and transport system to carry nutrients and other essential materials throughout their long extensions. This system requires the normal structure and functioning of a protein called tau. In Alzheimer’s, threads of tau protein twist into abnormal tangles inside brain cells, leading to a failure of the transport system. This failure is also strongly implicated in the decline and death of brain cells.
Current AD medications and management strategies may temporarily improve symptoms, help slow the progression of symptoms and improve quality of daily life, but the disease is not curable at this point. Behavioral management interventions (diet, exercise, cognitive stimulation, social interaction), education and other support services for caregivers are recommended.
AD is typically a disease of older people, though in rare cases it affects younger adults. Risk factors include old age, positive family history of the illness, female sex, prior history of head injury, prior history of depression, heat and vascular disease, high blood pressure, diabetes, high cholesterol, African American or Latin American heritage, Down’s Syndrome and low educational level. A growing body of research shows evidence that things that are bad for your heart are also bad for your brain (hypertension, diabetes, sleep apnea and high cholesterol). By the same token, things that are good for your heart are also good for your brain, like exercise and the Mediterranean-style diet.
Early-onset Alzheimer’s is an uncommon form of dementia that occurs in people age 30 to 60 and represents only about five percent of all people who have AD. Most people who have early-onset AD have the common form of Alzheimer’s Disease, which will progress in roughly the same way as it does in older people. Doctors do not yet understand why most cases of early onset Alzheimer’s appear at such a young age. But in a few hundred families worldwide, scientists have pinpointed several rare genes that directly cause Alzheimer’s. This less common form of early-onset Alzheimer’s is known as Familial Alzheimer’s Disease, and many family members in multiple generations are affected. Genetic testing can determine if you carry one of the genes that causes early-onset Alzheimer’s, but the decision to have this test is a personal one. While there is no cure for the disease, certain medications may help in managing symptoms.
- Short term memory loss
- Difficulties in planning or solving problems
- Difficulty completing familiar tasks
- Confusion with time or place
- Trouble understanding what one sees
- New problems with words in speaking or writing
- Misplacing things and losing the ability to retrace steps
- Decreased or poor judgment
- Withdrawal from work or social activities
- Uncharacteristic behaviors such as depression, paranoia, anxiety1
According to the Mayo Clinic, there is no specific test today that confirms you have AD. Your doctor will make a judgment about whether AD is the most likely cause of your symptoms based on the information you provide and results of various tests that can help clarify the diagnosis. Doctors can nearly always determine whether you have dementia, and they can often identify whether your dementia is due to AD, but AD can be diagnosed with complete accuracy only after death with microscopic examination of the brain
To help distinguish AD from other causes of dementia, doctors now typically rely on the following types of tests: physical and neurological exam, lab tests, mental status testing, brain imaging (CT scan, MRI, PET scan).
Accurate diagnosis is critical since there are dozens of causes of memory problems – and unlike Alzheimer’s, some of those can be treated and even reversed.
Other common types of irreversible dementia include
- Vascular dementia – caused by brain damage from impaired blood flow to the brain, such as with a stroke, but it can also result from other conditions that damage blood vessels and reduce circulation, depriving the brain of vital oxygen and nutrients
- Frontotemporal dementia – primarily affects the frontal an temporal lobes of the brain – the areas generally associated with personality, behavior and language
- Huntingdon’s Disease – in addition to dementia, incudes symptoms such as behavior changes, abnormal movements in the face and extremities, difficulty swallowing and speech impairment
- Parkinson’s Disease – a progressive disorder of the nervous system that affects movement ranging from tremors to slowing or freezing of movement. About half of persons with Parkinson’s may develop dementia.
- Dementia with Lewy bodies (DLB) – results in memory loss and thinking problems but have other early symptoms such as sleep disturbances, visual hallucinations, muscle rigidity and other parkinsonian movement
- Mixed dementia — abnormalities linked to more than one type of dementia occur simultaneously in the brain. Recent studies suggest that mixed dementia is more common than previously thought
Less common types of irreversible dementia include Wernicke-Korsakoff syndrome, Creutzfeldt-Jakob disease (CJD), AIDS-related dementia, alcohol dementia, traumatic brain injury. For more information on these topics, visit some of the websites listed on our RESOURCES link.
Irreversible dementia is progressive and does not get better. However, there are many conditions that might result in dementia-like symptoms but are treatable and even reversible. Some of these conditions include B-12 deficiency, medication side effects, depression, thyroid or endocrine problems, infections, electrolyte problems, dehydration and others. Accurate diagnosis is critical for proper treatment.
Planning is critical. As soon as possible after you are aware of the diagnosis, it is recommended that you begin taking steps to prepare for the road ahead. Caring for a person with Alzheimer’s is very costly, so consider the options available (and affordable) for you. Plan for the possibility that in-home care, adult day care, assisted living or nursing home care may eventually be necessary. While the person with AD is still able to express his/her wishes, decisions should be made regarding estate planning, wills, living wills, and other healthcare and end of life issues. Assistance from an eldercare attorney is strongly recommended – one who has the expertise to guide you down the very confusing road of long-term care planning. And, last but not least, find a local Alzheimer’s support group where you can get invaluable assistance in learning how to cope with this devastating disease. See our RESOURCES and FAQ links for more information on caregiving and support groups.
A Pocket Guide for the Alzheimer’s Caregiver by Daniel C. Potts, M.D. and Ellen Woodward Potts.
The 36-Hour Day A Lifesaver for Caring Families by Nancy L. Mace, M.A., and Peter V. Rabins, M.D., M.P.H.
The Dementia Concept by Joshua J. Freitas
Dementia Beyond Disease-Enhancing Well-Being by G. Allen Power, M.D.
Center for Medicare & Medicaid Services, Hand-in-Hand Training Series for Nursing Homes