Neuro Science  








Dementia is a brain condition. It affects memory, thinking, and behavior. It makes daily tasks difficult. It usually occurs in older people, but not restricted to older people. There is no complete cure as yet, but treatment can help manage symptoms.

Dementia is NOT a term indicating any single symptom and single root cause. It is a kind of an umbrella term that describes a wide varieties of symptoms associated with wide range of root causes.




What are Common Symptoms ?


There are wide varieties of symptoms associated with demantia. What kind of symptoms would appear would vary depending on persons, but we can list up symptoms that are most commonly observed.

  • Memory issues: People might forget things often, like where they put their keys or what they did yesterday.
  • Confusion: They could get mixed up with time, dates, or even familiar places.
  • Problem-solving: Simple tasks like paying bills or following a recipe can become difficult.
  • Speaking: They may struggle to find words or join conversations.
  • Mood changes: It's common to see mood swings, like getting sad or angry easily.
  • Trouble concentrating: People with dementia may have a hard time focusing on tasks or following a train of thought.
  • Misplacing items: They might put things in unusual places, like a wallet in the fridge or glasses in a drawer.
  • Social withdrawal: They may lose interest in social activities or hobbies they used to enjoy.
  • Poor judgment: Dementia can affect decision-making, leading to mistakes or risky choices.
  • Personality changes: People may become more irritable, suspicious, or fearful than before.




What are Common Causes ?


There are many different factors and root causes that lead to dementia. Followings are some of factors that are wiely known to cause dementia.

  • Alzheimer's disease: The most common cause of dementia. It happens when abnormal proteins build up in the brain, causing brain cell damage. - 60 to 60 % of dementia is considered to be associated with Alzheimer's disease.
  • Vascular dementia: This type is caused by reduced blood flow to the brain. It can happen after a stroke or due to blood vessel damage.
  • Lewy body dementia: Tiny protein deposits called Lewy bodies build up in the brain. These deposits can disrupt brain function and cause memory problems.
  • Frontotemporal dementia: A less common cause, affecting the front and side parts of the brain. This type of dementia usually affects people at a younger age.
  • Mixed dementia: Sometimes, a person can have more than one type of dementia, like Alzheimer's and vascular dementia together.
  • Other causes: Some other factors that can lead to dementia include infections, head injuries, or brain tumors. These are less common but still important to know.




What are common medication for dementia ?


Followings are the list of medications listed by Dementia (World Health Organization)

  • Cholinesterase inhibitors like donepezil are used to treat Alzheimer disease.
  • NMDA receptor antagonists like memantine are used for severe Alzheimer disease and vascular dementia.
  • Medicines to control blood pressure and cholesterol can prevent additional damage to the brain due to vascular dementia.
  • Selective serotonin reuptake inhibitors (SSRIs) can help with severe symptoms of depression in people living with dementia if lifestyle and social changes donít work, but  these should not be the first option.

Followings are the list of medication approved by FDA. The list came from Medications for Memory, Cognition and Dementia-Related Behaviors

  • Drugs that change disease progression
    • Aducanumab : monoclonal antibody that targets amyloid-beta plaques
    • Lecanemab : monoclonal antibody that targets amyloid-beta plaques
  • Drugs that treat symptoms
    • Cholinesterase inhibitors (Donepezil, Rivastigmine, Galantamine) :  increasing the levels of acetylcholine, a neurotransmitter involved in memory and learning, in the brain
    • Glutamate regulators (Memantine) :  regulating the activity of glutamate, a neurotransmitter involved in learning and memory.
    • Cholinesterase inhibitor + glutamate regulator (Donepezil and memantine) :  enhancing the effects of acetylcholine while also regulating glutamate levels, potentially resulting in improved cognitive function and slower disease progression
    • Orexin receptor antagonist (Suvorexant) : treating sleep disorders, like insomnia


NOTE : These medications are usually used to mitigate the symptoms. They do not cure dementia.




How dementia brain differs from normal brain ?



Following images shows an example of Alzheimer patient's brain scan representing GCA. GCA stands for Global Cortical Atrophy. The GCA scale is a semi-quantitative rating system used to assess the degree of cortical atrophy visible on brain scans of patients with dementia. Cortical atrophy refers to the shrinking or loss of brain tissue in the cerebral cortex, the outer layer of the brain responsible for many higher cognitive functions. This atrophy can be indicative of neurodegenerative diseases such as Alzheimer's disease, frontotemporal dementia, and other types of dementia.

Image source : Dementia - Role of MRI


The GCA scale typically ranges from 0 to 3, with higher scores representing greater atrophy:

  • GCA 0: No significant cortical atrophy.
  • GCA 1: Mild cortical atrophy. There is a slight widening of the sulci (the grooves on the surface of the brain) and a mild reduction in the volume of the gyri (the ridges on the surface of the brain).
  • GCA 2: Moderate cortical atrophy. There is a more pronounced widening of the sulci and a reduction in the volume of the gyri. The ventricles, the fluid-filled spaces within the brain, may also appear enlarged.
  • GCA 3: Severe cortical atrophy. The sulci are significantly widened, and the gyri are substantially reduced in volume. The ventricles may appear severely enlarged.



Following is a pair of MRI image comparing crosecion of the brain for a normal person and a dementia(Alzheimer) patient. As you would notice, brain is shrinked overall (showing more of black area) and himpocampus (highlighed in red) are damaged in the patient's brain.

Image Source : All you need to know about brain scans and dementia


Following is a pair of PET image comparing brain activity for a normal person and a dementia(Alzheimer) patient. As you would notice, the patient's brain shows less active (showing less area of bright colors) and more Amyloid accumulation (more area of bright colors).


Image Source : All you need to know about brain scans and dementia