Brain
Introduction
Most old people suffer a slight decline in intelligence, learning abilities,
short-term memory and reaction time. This decline is often not significant until
they are in their mid-70s. Pathological problems (including dementias) have
more significant effects on functioning.
Age-related structural changes in the brain
Dementia
(a pathological problem)
Dementia is not the name of a specific disease, but a generic term. It is a
global impairment of every aspect of the intellect, memory and personality,
without any alteration of consciousness. It may be non-progressive or transient
(e.g. trauma, hypoxia) or progressive (caused by an extrinsic or metabolic cerebral
disorder). This section focuses on dementias caused by permanent structural
changes in the brain, which occur in approximately 2% of people aged 65-75 and
10-20% of people aged over 80. Alzheimer’s is the most common, but there
are several other types of dementia.
Cerebral problems affect localized parts of the brain, typically sparing some brain function. The patterns of impaired and spared function tend to differ with dementia type. However, it may be hard to tell dementias apart without exhaustive neurophysiologic testing.
Different
areas of the brain have different functional specialization
and so impairments in dementia depend on the area affected.
Alzheimer’s
disease
This accounts for almost half of all dementia. It is a dementia of the temporal
and parietal lobes and the earliest (insidious) symptom is usually memory loss.
As it progresses, its symptoms interfere with social and occupational functioning.
Typical
brain structure in Alzheimer’s
Changes which occur in the brains of most elderly people but are more pronounced
in those with Alzheimer’s disease are:
Risk factors for Alzheimer’s
Protective factors that make Alzheimer’s less likely
Vascular
(previously called multi-infarct) dementia
This accounts for 10-20% of dementias but a further 20% of patients have both
vascular dementia and Alzheimer’s. It occurs when there is an accumulation
of small focal deficits caused by a number of small strokes. Because of this,
it tends to progress in steps and there is patchy distribution of cognitive
problems. Lesions tend to be frontal and sub cortical.
Shower of minor infarcts leading to vascular dementia
Risk factors for vascular dementia
Huntington’s
chorea
Sub cortical dementia is associated with Huntington’s chorea (a familial
disorder) and so neurological symptoms dominate the psychological ones.
Potentially
reversible dementias
Potentially reversible dementias are caused by:
Alcoholic encephalopathy usually manifests as a cortical problem with amnesia (Wernicke-Korsakoff syndrome) but there may also be frontal lobe dysfunction when the patient is undernourished.
Brain problems which are not dementias (pathological and non-pathological)
"Like beauty, disturbed behaviors are in the eye of
the beholder."
G. Fulop, Brocklehurst's Textbook
of Geriatric Medicine and Gerontology, 1998
Transient
global amnesia
This is an episodic problem of unknown cause which mainly affects older people.
It lasts several hours and is followed by apparent complete recovery except
that the person cannot recall the event. It does not indicate the onset of a
stroke or dementia.
Age-associated
memory impairment
Young and old people alike forget things. Older people are less able to remember
lists of numbers or words but this is probably not due to ageing, but to a so-called
cohort effect. People who are in their 80s now generally had less good education
than people in their 60s and this would be enough to explain an apparent decline
in performance in memory tests in the very old.
Chronic
subdural haematoma
Acute and subacute haematoma (bleeding from small veins between the protective
membrane called the dura and the brain it surrounds) occurs when physical injury
results in the development of shearing forces. Chronic haematomas are almost
uniquely a problem of the older person and the initial trauma is often mild
and may go completely unnoticed.
Factors include:
Problems
of daily living
Brain dysfunction is one of the most limiting and life-changing conditions a
person can have. It may mean the old person has to live in an institution.
Tests
Mini Mental States Test
___________________________________________________
Orientation
What is the (year)(season)(day)(month)Where are we (country)(city)(part of London)(number of flat/house)(name of street)
Registration
Name three objects' one second to say each
Then ask the patient to name all three after you have said them
Give one point for each correct answer
Then repeat them until he or she learns all three
Count trials and recordTRIALS
Attention and calculation
Serial 7s - one point for each correct
Stop after five answers
Alternatively spell "world" backwards
Recall
Ask for the three objects repeated above
Give one point for each correct
Language
Name a pencil, and watch (two points)
Repeat the following: "No ifs, ands or buts" (one point)
Follow a three-stage command: "take a paper in your right hand, fold it in half and put it on the floor" (three points)
Read and obey the following: Close your eyes (one point)
Write a sentence (one point, must contain a subject, verb and object to score one point)
Copy a design (one point)Max score
5
5
3
53
9
Total score
Actual score
____
____
____
________
____
____
The
Abbreviated Mental Test
This test indicates the memory problems a patient has, and so it can help with
differential diagnoses, treatment and rehabilitation. However, depressed and
aphasic patients may not do well on this test even if they do not have a memory
problem. The test asks the following:
1. Name
2. Date of birth
3. Age
4. Date and time of day
5. Address
6. Name of Prime Minister
7. Date of First World War
8. Place now at
9. Recall of an address 5 minutes after being told the address.
10. Counting backwards from 20 to 1.
To be of most use, this test needs to be repeated over time.
See also
Self-neglect, depression,
confusion.
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