C28 - Effects of Ageing on the Nervous System

Question 1

What is Alzheimer’s disease?

Answer 1

AD is a degenerative disease of the nervous system, which particularly affects the temporal and frontal lobes of the brain.

Question 2

What are the causes of Alzheimer’s disease?

Answer 2

• Increasing age
• Family history of the condition
• Familial AD, when some alleles of a particular gene are inherited. (Very rare)
• Genetic differences e.g. some variants of the apolipoprotein E gene (ApoE) May act as risk factors
• Severe or repeated head injury
• Stroke
• Low level of education and intellectual activity

Question 3

What’s vascular dementia?

Answer 3

Dementia which occurs due to factors associated with cardiovascular disease.
E.g. high blood pressure, high blood cholesterol and smoking.

Other symptoms of Alzheimer’s disease (AD) are not usually present.

Question 4

How can the symptoms of AD be divided (into 3 stages)?

Answer 4

Early stages (mild)

Mid-stage (moderate)

Late-stage (severe)

Question 5

What happens in/are the symptoms in the early stages of Alzheimer’s disease (AD)?
(Mild)

Answer 5

The person can continue to function independently, since memory loss and cognitive deficits are compensated for by the person.

They may start to forget family members’ names, places, objects, and events and find it difficult to express what they want to say.

They may repeat themselves, have reduced ability to make decisions and show poor judgement.

They may also show early signs of mood changes.

Question 6

What happens in/are the symptoms in the mid-stages of Alzheimer’s disease (AD)?
(Moderate)

Answer 6

Personality changes and physical problems develop and cognitive ability continues to decline.

Person becomes more dependent on others for care and support for daily activities.

Most are unaware they’re forgetting things and can’t communicate coherently.

They’ll show increasing confusion, disorientation, obsessive/impulsive behaviour, disturbed sleep and mood swings.

Poorer judgment of distance.

Question 7

What happens in/are the symptoms in the late stages of Alzheimer’s disease (AD)?
(Severe)

Answer 7

Loss of control of bodily functions (e.g. urinary and bowel incontinence).

More frequent confusion and disorientation and big personality change.

Language severely affected and can be completely lost.

May become violent and suspicious of people.

Dysphagia (may lose ability to swallow).

Question 8

What proteins cause the formation of tangles in the brain, causing Alzheimer’s disease?

Answer 8

Tau proteins

Question 9

What proteins cause the formation of plaques in the brain, causing Alzheimer’s disease?

Answer 9

Beta amyloid proteins

Question 10

What 2 proteins cause the destruction of brain cells in AD?

Answer 10

Tau proteins (in neurones) and beta amyloid (in myelin sheath surrounding neurones).

Question 11

What causes Alzheimer’s disease (pathologically)?

Answer 11

Tau proteins exist in neurones and stabilise microtubules.

When Tau proteins become defective, it results in the death of the neurone.
Neurofibrillary tangles form - twisted aggregates of Tau protein that have become hyper-phosphorylated and build up inside the neurones.
When this occurs, the microtubules disintegrate, causing the neurone transport system to collapse (resulting in biochemical communication malfunction).

Proteins are also found in the myelin sheath around neurones. Abnormal breakdown of these proteins produces beta amyloid proteins. These accumulate and form plaques around the axon and dendrites.

Question 12

How does a healthy brain compare to a brain with Alzheimer’s disease?

Answer 12

A brain with Alzheimer’s is:

• smaller
• more deeply folded
• has plaques and tangles

Question 13

What are the (3) theories for the molecular causes of AD?

Answer 13

Herpes simplex virus type 1 (may have an affect in people with the ApoE gene)

Age related myelin breakdown in the brain. Iron released during myelin breakdown is thought to cause further damage.

Inflammatory processes associated with aging. E.g. formation of toxic proteins on brain neurone surfaces is thought to be a beta amyloid derivative.

Question 14

What’s presbycusis?

Answer 14

A progressive disorder, resulting in significant hearing problems with increased age.

Question 15

What causes age-related hearing loss?

Answer 15

When sensitive hair cells inside the cochlea (inner ear) die and the neurones in the auditory nerve gradually become damaged or die.

Question 16

What is ARMD?

Answer 16

Age related macular degeneration

A medical condition that usually affects older adults.
It can result in loss of vision in the macula due to damage to the retina.
It’s a major cause of blindness and visual impairment.

(There are 2 types: dry and wet)

Question 17

What’s dry ARMD (age-related macular degeneration)?

Answer 17

Loss of vision in the macula due to damage to the retina.

This occurs when cellular debris (called drusen) accumulates between the retina and choroid, causing the retina to become detached.
(Most common form of ARMD)

Question 18

What’s wet ARMD (age-related macular degeneration)?

Answer 18

Loss of vision in the macula due to damage to the retina.

This is more severe than dry ARMD, as blood vessels grow up from behind the retina.
The blood vessels can leak blood and fluid into the retina, which can cause scarring and damage to the macula, resulting in visual distortion and blind spots.
The retina can also become detached.

(It can be treated with laser coagulation and medication can prevent growth of blood vessels).

Question 19

What’s a cataract?

Answer 19

The clouding of the lens in the eye which leads to a decrease in vision.

Question 20

What are the 3 main types of cataract?

Answer 20

Nuclear

Cortical

Subcapsular

Question 21

What are nuclear cataracts?

Answer 21

A type of cataract which makes it difficult to recognise the intensity of colours (but reading vision won’t normally change).

Question 22

What are cortical cataracts?

Answer 22

A type of cataract which can cause problems with glare when driving.
There may also be difficulty in reading and low sun in winter causes discomfort as it shines into the eyes.

Question 23

What are subcapsular cataracts?

Answer 23

A type of cataract which can make vision poor during the daytime, making it difficult for a person to drive and have more problems reading.

Question 24

What factors increase the risk of cataracts?

Answer 24

Ageing
Diabetes
Smoking
Regularly drinking excessive amounts of alcohol
Lifelong exposure of the eyes to UV sunlight
Long term or high dose use of corticosteroid
Previous eye surgery or injury
Family history of cataracts

Question 25

How is age-related cataracts treated?

Answer 25

By using stronger glasses and brighter reading lights.

However, as it worsens, surgery would be needed.
The cloudy lens would be removed through a small incision in the eye and replaced with a clear plastic one.

Question 26

What’s glaucoma?

Answer 26

Eye conditions related to a damaged optic nerve.
This occurs due to increased intraocular when the aqueous humour fails to drain properly.

It can lead to permanent blindness.

Question 27

What are the 4 main types of glaucoma?

Answer 27

Chronic open-angle glaucoma

Primary angle-closure glaucoma a.k.a Acute glaucoma

Secondary glaucoma

Developmental glaucoma (congenital glaucoma)

Question 28

What’s chronic open-angle glaucoma?

Answer 28

A type of glaucoma caused by blockage of the drainage channels which normally allow the aqueous humour to drain away.
It can result in tunnel vision, leading to blindness.

It can be treated using eye drops or by opening the drainage channels via surgery.
(Most common type with slow development).

Question 29

What’s primary angle-closure glaucoma / acute glaucoma?

Answer 29

A type of glaucoma where the edge of the iris and cornea come into contact with each other.

This causes pressure to rise suddenly as the aqueous fluid cannot reach the drainage channels between them.
The eye becomes very red and painful, causing the person to have severe headaches, blurred vision, nausea, and vomiting.

(Rare and can be chronic. Also known as cute as it can develop rapidly. This form needs immediate treatment to reduce pressure in the eye, followed by laser treatment or surgery.)

Question 30

What is secondary glaucoma?

Answer 30

A type of glaucoma which can occur as a result of an injury to the eye or different eye condition e.g. uveitis (inflammation of the iris or inflammation of the iris and the ciliary body).

Question 31

What is developmental glaucoma (congenital glaucoma)?

Answer 31

A rare form of glaucoma that can be very serious.

It is usually present at birth or develops shortly after birth.

Question 32

What are the three main effects of ageing on the nervous system?

Answer 32

Hearing impairments

Visual impairments e.g. ARMD, cataracts and glaucoma

Memory loss

Question 33

How does age related memory loss differ from dementia?

Answer 33

Age related memory loss isn’t disabling.
The memory lapses have little impact on a persons performance and ability to complete normal daily activities.

However, when memory loss becomes severe and disrupts a persons social activities, it is possible that the person may be experiencing signs of Alzheimer’s disease.

Question 34

How can age related memory loss be reduced? (By changes in lifestyle)

Answer 34

Regular exercise – it boosts brain growth factors encourages the development of new brain cells

Social interaction – helps brain function by involving activities that challenge the mind. It also helps reduce stress and depression.

Eating plenty of fruit,vegetable and drinks such as green tea – these contain many antioxidants. Foods rich in omega-3 fats such as tuna and walnuts have been found to improve memory.

Managing stress – cortisol, the stress hormone, damages the brain over time and can lead to memory problems.

Sufficient sleep – is needed for memory consolidation (the process of forming and storing new memories). Lack of sleep also reduces growth of new neurons in the hippocampus. Lack of can also cause problems with memory, concentration and decision-making.

Not smoking – smoking increases the risk of vascular disorders that can cause strokes and constrict arteries that deliver oxygen to the brain.