Sudha Seshadri, MD, founding director of the Biggs Institute, answers frequently asked questions surrounding Alzheimer’s disease and other dementias.
Is it normal aging or dementia?
Dr. Seshadri: In short, if one occasionally forgets a word or to do something, if one is slower but usually finds the answer it is likely normal aging. If one frequently and persistently forgets important events or information, it more likely to be the early stage of a dementia. If you suspect something is wrong, talking to your doctor is a very good idea. Dementia does not always begin as a memory problem, it can be a slow decline in speech (as it was for Bruce Willis), ability to visually recognize objects, to do complex tasks like driving or to know what is socially appropriate behavior.
What’s the difference between Alzheimer’s disease and dementia?
Dr. Seshadri: Dementia is an “umbrella term” that we use when a person begins to show a decline in their memory or thinking, ability to perceive or communicate or a change in their behavior that gets progressively worse and prevents them from doing the work, home or leisure related activities they used to do.
There are many causes of dementia and one patient may have more than one cause for their dementia.
The most common cause of dementia is Alzheimer disease.
What is Alzheimer’s disease?
Dr. Seshadri: We define types of dementia based on a combination of symptoms and signs along with what we find in the brain of the person suffering from dementia.
In Alzheimer’s disease two types of proteins accumulate in the brain in an abnormal form and abnormal (excessive) amount. These proteins are ‘beta-amyloid’ (also called ‘amyloid’) and ‘tau’ that accumulate as ‘plaques’ and ‘tangles’ respectively.
Along with this accumulation other changes like inflammation also play a role and ultimately nerve cells (neurons) lose their connections with one another (synapses) and die.
The brain has other cells that support the neurons (called ‘glia’) and these supporting cells and blood vessels in the brain are also important in Alzheimer’s and other types of dementia.
Does having a definitive diagnosis of a specific type of dementia helpful in how we care for/with PLWD? How does care differ with Alzheimer’s disease, frontotemporal dementia (FTD), Lewy body dementia (LBD or DLB), Huntington’s disease or vascular dementia is the correct diagnosis?
Dr. Seshadri: Some (few) types of ‘dementia’ can be treated and reversed. These include vitamin deficiencies, thyroid problems, some infections, fluid accumulating in the brain (NPH or normal pressure hydrocephalus), depression masquerading as dementia, brain tumors, some cancers and strokes.
Even if the diagnosis is an irreversible dementia, the correct diagnosis or ‘type’ helps the doctor, patient and family anticipate and plan for what is to come. Some symptoms like walking (in Lewy body dementia) or speech (in frontotemporal dementia) problems can be improved. A correct diagnosis can ensure that ineffective medicines are not used- for example some medicines used for Alzheimer disease do not help persons with FTD. It can make the physician more careful in prescribing certain medicines that may cause side-effects. For example, in persons with Lewy body dementia, some medicines to help Parkinson’s disease symptoms can lead to patients having scary visual hallucinations. Also, with the right diagnosis patient may be able to enter a clinical trial specific for their condition.
What are the chances of inheriting dementia? Does this vary by type of dementia?
Dr. Seshadri: Yes, knowing the type of dementia helps predict the risk of inheriting dementia.
There are some strongly heritable dementias. For example, Huntington’s disease, some types of frontotemporal dementia and prion disease, a small proportion (less than 5%) of persons with early-onset Alzheimer’s disease where symptoms begin before the age of 65, are all strongly heritable.
Genetic testing may identify whether or not someone is a carrier for a disease-causing mutation. If a mutation is found, there are now several clinical trials with very specific treatments targeting the gene. For example at the Biggs Institute for Alzheimer’s and Neurodegenerative Diseases, we are conducting trials on persons carrying mutations in the C9orf72, progranulin [GRN] genes and later this year we expect to start trials for carriers of early-onset Alzheimer mutations in APP, PSEN1 or PSEN2 genes.
For most persons with Alzheimer’s disease, the strongest genetic risk factor is a gene called APOE. Most of us have two APOE3 variants and are average risk. Having one copy of an E4 variant doubles the risk and having two copies of an E4 variant increases the risk over 10 times, but you can have E4 and never develop dementia. Also, you can have no E4 and still develop dementia. In fact, 50% of the people who develop dementia do not have an E4.
In most persons having one or more relatives- parents, siblings, grandparents, uncles, aunts, cousins- with dementia, the risk is only slightly higher than average. Dementia is considered a complex genetic disease (like diabetes) with many genes and many non-genetic factors affecting the risk.
We are able to offer genetic counseling at the Biggs Institute. Persons who are healthy but concerned about future risk of dementia can also monitor their own brain health online through our Brain Health Registry.
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