Date：2023-08-16

Are you suffering from memory loss?

You may have Alzheimer's Disease or Frontotemporal Dementia!

According to relevant research, one out of every ten elderly people aged 70 or above and one out of every three elderly people aged 85 or above suffer from dementia. With the ageing population, the number of dementia patients in Hong Kong is expected to reach 300,000 by 2039[4].

Dementia is a general term for the decline in cognitive functioning, which includes thinking, remembering and reasoning, to a degree that it disrupts one’s daily life. Alzheimer’s disease and frontotemporal dementia are common types of dementia.

What is Frontotemporal Dementia (FTD)?

FTD is a form of dementia caused by the gradual atrophy of the frontal and temporal lobes of the brain. This condition typically affects individuals between the ages of 45 and 64 and is considered as early-onset dementia. However, since the patient's memory and visual-spatial abilities are usually not affected at an early stage, i.e., no common symptoms of confusion or memory loss, it is difficult for others to notice.

Early symptoms include:

• Changes in mood and thinking patterns (e.g. becoming depressed, anxious, irritable, or impulsive)
• Lack of judgment (e.g. leaving the stove on in the kitchen or talking excessively when it should be quiet)
• Language problems (e.g. not being able to express oneself or understand complex speech)
• Repetitive compulsive behaviour (e.g. keep clapping or smacking lips)

What is Alzheimer’s Disease (AD)?

AD is a brain disorder where a bunch of protein accumulate in AD patients’ brain with no reason. The death rate of neurons in patients is faster than that of average people, resulting in a gradual deterioration of brain function.

Early symptoms include:

• Confusion
• Memory loss
• Changes in cognitive function, behaviour, or personality

Does dementia run in families?

39-50% of FTD patients have a family history of dementia, of which 10-23% are due to dominant inheritance[1]. The heritability of early-onset AD is about 60-80%[3]. More details can be found in our previous blog post.

What is the difference between dementia and memory loss?

Human memory declines with age, which is a normal ageing phenomenon. Yet, dementia is not simply a normal ageing or memory decline, but rather a brain disorder. Memory loss is just one of the symptoms of dementia.

Diagnosis of FTD and AD

Approximately 36% of AD cases cannot distinguish from FTD based on clinical diagnostic criteria while 52% of AD cases meet the criteria for possible FTD[1]. The high similarity, or even overlapping of symptoms between AD and FTD makes it difficult for doctors to diagnose, and even leads to misdiagnosis. This ultimately increases the time it takes for patients to be diagnosed and delays treatment. To save time and money on diagnosis, genetic testing could identify the disease early.

Common genes related to FTD include: C9ORF72, MAPT, GRN, TARDBP, VCP, CHMB2P, TBK1

Common genes related to AD include: APP, PSEN1, PSEN2, APOE, TREM2, MAPT

*All these genes are included in our genetic tests.

Refer to the chart below to see which genetic testing is suitable for you:

*CoGenesis® Neuro Test include complete version, adult-onset and childhood-onset, please feel free to ask us more.

Although there is currently no cure for FTD and AD at this moment, medication and lifestyle changes can be used to alleviate symptoms or delay the progression of the disease. It is worth mentioning that a new drug called Lecanemab (Leqembi™) for treating early AD patients under Eisai, a Japanese pharmaceutical company, received full approval from the US Food and Drug Administration (FDA) on July 2023. This is undoubtedly good news for early AD patients. However, its side effects pose a greater risk to patients with two pairs of common AD-related genes, the APOE4 gene. Therefore, patients who want to use Lecanemab should first undergo our APOE test or AD risk level assessment to ensure the drug's maximum effectiveness and safety. For more information, please consult a genetic professional.

In Hong Kong, there are also currently various companies discovering new drugs for rare diseases, such as FTD and AD. For example, Rare Power, a biotech company founded by Professor Edwin, Chan Ho Yin, who has been researching rare diseases for 25 years and is also the founder of Nexus of Rare Neurodegenerative Diseases (NRND).

Codex is here to walk alongside you, please feel free to ask our genetic experts for more.

Reference:

1. Gossye, H., Van Broeckhoven, C., & Engelborghs, S. (2019). The Use of Biomarkers and Genetic Screening to Diagnose Frontotemporal Dementia: Evidence and Clinical Implications. Frontiers in neuroscience, 13, 757. https://doi.org/10.3389/fnins.2019.00757
2. National Institute on Aging. What are Frontotemporal Disorders? Causes, Symptoms, and Treatment. Available at: https://www.nia.nih.gov/health/what-are-frontotemporal-disorders
3. Van Cauwenberghe, C., Van Broeckhoven, C. & Sleegers, K. The genetic landscape of Alzheimer disease: clinical implications and perspectives. Genet Med 18, 421–430 (2016). https://doi.org/10.1038/gim.2015.117
4. Yu, R., Chau, P. H., McGhee, S. M., Cheung, W. L., Chan, K. C., Cheung, S. H., & Woo, J. (2012). Trends in prevalence and mortality of dementia in elderly Hong Kong population: projections, disease burden, and implications for long-term care. International journal of Alzheimer's disease, 2012, 406852. https://doi.org/10.1155/2012/406852