What is dementia?
Dementia is a general term for a loss of intellectual functioning—such as remembering, reasoning, paying attention, and using language—that is severe enough to interfere with a person’s everyday life. Dementia symptoms may accompany certain diseases or physical conditions.
The most common causes of progressive dementia are reviewed below. Other reversible medical conditions can also cause dementia symptoms. These can include depression, drug reactions, infections, sleep problems, vitamin deficiencies, thyroid problems, head injuries, brain tumors, and excessive alcohol use. Because dementia symptoms can result from treatable medical conditions, it is important for persons with these symptoms to be assessed as soon as possible by a medical provider.
Alzheimer’s disease (AD) is the most common cause of dementia, representing 60-80% of all dementia cases. AD is a progressive, degenerative disease that attacks the brain and results in impaired memory, thinking, and behavior. Symptoms of AD include gradual memory loss, decline in ability to perform routine tasks, disorientation in time and space, poor judgment, loss of interest and motivation, difficulty in learning new things, personality changes, and loss of language skills. As with all diseases that cause dementia, disease progression varies from person to person. From the onset of symptoms, a person with Alzheimer’s may live from 3 to 20 years, with an average lifespan of 8-10 years from diagnosis. There are currently a few drugs prescribed to treat the symptoms of Alzheimer’s disease. For some people, these treatments improve daily life by enhancing memory and cognitive ability. See this site for more specific information: https://www.nia.nih.gov/health/alzheimers-disease-fact-sheet.
Vascular dementia (VaD) refers to cognitive impairment caused by disruptions of blood flow to parts of the brain. One common type of VaD is multi-infarct dementia when a series of strokes block small arteries and destroy brain tissue. These strokes can damage areas of the brain responsible for specific functions. They can also produce general symptoms of dementia, mimicking Alzheimer’s disease. In fact, VaD occurs frequently as a “mixed dementia” with Alzheimer’s disease. Symptoms may include problems with recent memory, confusion, getting lost in familiar places, difficulty following instructions, loss of interest and motivation, sudden mood changes, laughing or crying inappropriately, difficulty walking, falls, and increased rigidity. Impairments from VaD can occur in a step-wise fashion, rather than the slow, steady decline more typical of Alzheimer’s disease. Although vascular dementia is not reversible or curable, treating vascular risk factors like high blood pressure and diabetes may slow disease progression. For more information, see https://www.nia.nih.gov/health/vascular-dementia.
Dementia with Lewy bodies
Dementia with Lewy bodies (DLB) is an irreversible, progressive brain disease associated with abnormal protein deposits in the brain called Lewy bodies. Lewy bodies are also often found in people with Parkinson’s disease. Persons with DLB whose cognitive symptoms appear first may be diagnosed with Lewy body dementia (LBD), while persons who present first with Parkinsonian symptoms followed by cognitive problems are generally diagnosed with Parkinson’s disease dementia (PDD).
Typical DLB symptoms include fluctuating cognition, with pronounced variations in attention and alertness; recurring visual hallucinations; and features of Parkinsonism, including tremor, stiffness, slowed movement, and impaired balance and coordination. Some persons with DLB experience a sleep disorder that causes them to act out their dreams, a condition often appearing many years before other symptoms. Paranoia, delusions, and depression may also be present. Significant memory impairment may not be an early symptom. Medical providers are cautious in prescribing medications for those thought to have dementia with Lewy bodies. People with DLB often respond positively to drugs that treat Alzheimer’s disease, but can have extremely adverse reactions to some antipsychotic, antidepressant, and Parkinson’s disease drugs. See this site for more specific information on Lewy body dementia: https://www.nia.nih.gov/health/topics/lewy-body-dementias.
Frontotemporal dementia (FTD) includes disorders that cause tissue deterioration and shrinkage in the brain’s frontal and temporal lobes. These parts of the brain are responsible for language skills, attention, self-insight, the capacity to organize, and the ability to control movement. Persons with FTD can struggle with making plans and decisions, solving problems, initiating activity, and controlling impulses. This disorder is more rare than other forms of dementia and often occurs at a younger age—the National Institute on Aging reports that about 60% of people with FTD are 45-64 years old (https://www.nia.nih.gov/health/what-are-frontotemporal-disorders).
There are three main types of frontotemporal dementia:
The behavioral variant affects mood, personality, and behavior. Symptoms include apathy, anger, lack of empathy, loss of inhibitions, rudeness, impatience, restlessness, poor hygiene, poor judgment, overeating, repetitive motions, and rigid behavior. Persons with the diagnosis may lack awareness or concern that their behavior has changed.
The language variant (Primary Progressive Aphasia) is characterized by loss of language abilities, including the ability to speak, write, read, or understand another person’s speech.
The movement variants (Corticobasal Syndrome and Progressive Supranuclear Palsy) can result in loss of muscle control, rigidity, difficulty swallowing, balance problems, and falls.
Many FTD symptoms precede the development of memory loss. The drugs for treating Alzheimer’s disease are not effective for FTD. Providers may treat with antidepressants or antipsychotic medications, depending on symptoms. For more information on FTD, see this site: www.theaftd.org.
“Mixed dementia” is the diagnosis when a person appears to have more than one type of dementia. The most common types of mixed dementia are Alzheimer’s disease with vascular dementia and dementia with Lewy bodies with Alzheimer’s disease. Studies suggest that people age 80 and older with dementia probably have a combination of AD, VaD, and neurodegeneration from other causes, making a specific dementia diagnosis difficult (https://www.nia.nih.gov/health/what-is-dementia).