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 dont 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.

NOTE : Cognitive/behavioral symptoms of GCA level

    The Global Cortical Atrophy (GCA) scale is used to assess the severity of cortical atrophy, which is common in various forms of dementia. Here is a list of common cognitive and behavioral symptoms associated with each stage of GCA:

    • GCA Stage 0 (No Cortical Atrophy)
      • Cognitive Symptoms: Normal cognitive function; no signs of memory loss or cognitive impairment.
      • Behavioral Symptoms: None, as the individual functions normally without any noticeable changes.
    • GCA Stage 1 (Mild Cortical Atrophy)
      • Cognitive Symptoms: Very mild cognitive decline, such as occasional lapses in memory (e.g., forgetting where everyday objects are placed, or familiar names). These changes are often too subtle to interfere with daily life or be detected in a clinical interview.
      • Behavioral Symptoms: Increased frequency of minor forgetfulness, which might cause slight frustration or anxiety but typically does not impact work or social interactions.
    • GCA Stage 2 (Moderate Cortical Atrophy)
      • Cognitive Symptoms: Mild cognitive decline becomes more noticeable. Symptoms include getting lost in familiar places, difficulty retaining new information, forgetting names of people just met, misplacing valuable items, trouble concentrating, and decreased performance at work.
      • Behavioral Symptoms: Increased anxiety, difficulty in social settings, and growing awareness of cognitive difficulties. Individuals might start to avoid challenging situations to hide their cognitive issues.
    • GCA Stage 3 (Severe Cortical Atrophy)
      • Cognitive Symptoms: Moderate cognitive decline. Individuals show significant deficits in memory, such as forgetting personal history details, and have difficulty organizing and planning daily activities. They might be disoriented about time and place.
      • Behavioral Symptoms: Higher levels of anxiety, frustration, and depression due to the noticeable impact on daily functioning. There might be personality changes, such as increased irritability or withdrawal from social interactions.

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

What are common causes of dementia ?

Dementia is not a single disease but a general term for a decline in mental ability severe enough to interfere with daily life. It is caused by damage to or loss of nerve cells and their connections in the brain. There are many different causes of dementia, each with its own set of symptoms and progression.

Common Causes of Dementia:

The most prevalent causes of dementia involve various neurodegenerative diseases and vascular conditions that progressively damage brain cells. These conditions are responsible for the majority of dementia cases and typically lead to a gradual decline in cognitive function and memory.

  • Alzheimerís Disease
    • Description: This is the most common cause of dementia, accounting for 60-80% of cases.
    • Pathology: It is characterized by the buildup of proteins, specifically amyloid plaques and tau tangles, in the brain that damage and kill nerve cells.
    • Symptoms: Memory loss, confusion, difficulty with language and problem-solving, and changes in behavior.
  • Vascular Dementia
    • Description: This is the second most common cause of dementia.
    • Pathology: It is caused by reduced blood flow to the brain, often due to stroke or other cardiovascular problems that damage brain tissue.
    • Symptoms: Problems with planning and organization, slowed thinking, and difficulties with attention and concentration.
  • Lewy Body Dementia
    • Description: This type of dementia is characterized by the presence of Lewy bodies, which are abnormal protein deposits that damage brain cells.
    • Pathology: The Lewy bodies disrupt the brain's normal functioning, particularly affecting areas that regulate behavior, cognition, and movement.
    • Symptoms: Visual hallucinations, fluctuations in alertness and attention, motor symptoms similar to Parkinsonís disease, and REM sleep behavior disorder.
  • Frontotemporal Dementia (FTD)
    • Description: This is a group of disorders that primarily affect the frontal and temporal lobes of the brain.
    • Pathology: The degeneration of nerve cells in these regions leads to significant changes in personality, behavior, and language.
    • Symptoms: Drastic changes in social behavior and personality, impulsivity, problems with speech and language, and sometimes motor symptoms.

Other Causes of Dementia:

Apart from the more common types, there are several other causes of dementia that may be less frequent but still significantly impact cognitive health. These include genetic disorders, mixed forms of dementia, and other neurodegenerative diseases that can manifest in unique and complex ways.

  • Parkinsonís Disease
    • Description: A neurodegenerative disorder primarily affecting movement.
    • Pathology: Parkinsonís disease dementia occurs as the disease progresses, affecting cognitive functions.
    • Symptoms: Similar to Lewy body dementia, including visual hallucinations, impaired memory, and motor dysfunctions.
  • Huntingtonís Disease
    • Description: A genetic disorder that causes the progressive breakdown of nerve cells in the brain.
    • Pathology: Huntington's disease is caused by a genetic mutation that leads to widespread brain degeneration.
    • Symptoms: Cognitive decline, personality changes, and uncontrolled movements (chorea).
  • Mixed Dementia
    • Description: This occurs when a person has more than one type of dementia simultaneously, such as Alzheimerís disease and vascular dementia.
    • Pathology: The coexistence of multiple types of brain abnormalities.
    • Symptoms: A combination of symptoms from the different types of dementia present.
  • Other Less Common Causes
    • Creutzfeldt-Jakob Disease: A rare, degenerative brain disorder caused by prions, leading to rapid mental deterioration.
    • Normal Pressure Hydrocephalus: An accumulation of cerebrospinal fluid in the brain's ventricles, causing symptoms similar to dementia.
    • Infections: Certain infections such as HIV and syphilis can lead to cognitive impairment if untreated.

Reversible Causes of Dementia-like Symptoms:

Not all conditions that mimic dementia are permanent. Some can be reversed with appropriate treatment, leading to a restoration of normal cognitive function. These reversible causes often stem from metabolic imbalances, vitamin deficiencies, infections, and other treatable medical conditions.

  • Infections and Immune Disorders
    • Description: Some infections and autoimmune diseases can cause temporary cognitive impairment.
    • Examples: Encephalitis, meningitis, and paraneoplastic syndromes.
  • Metabolic or Endocrine Problems
    • Description: Issues with the thyroid gland or blood sugar levels can lead to cognitive issues.
    • Examples: Hypothyroidism and hypoglycemia.
  • Vitamin Deficiencies
    • Description: Lack of certain vitamins, such as B12, can lead to cognitive problems.
    • Examples: Vitamin B12 deficiency can cause neurological damage if untreated.