Dementia
See Also:
Dementia:
Introduction
Dementia: Types
Dementia:
Causes & Risk Factors
Dementia: Signs &
Symptoms
Dementia: Stages
Dementia: Medical Tests
& Diagnosis Methods
Dementia:
Treatment & Prevention Options
Types of Dementia
There are different ways to classify dementing
disorders based on common features, in terms of their
progressive nature, and parts of brain affected:
I. Cortical Dementia:
Dementia caused due to damage to the cortex or outer
layer is cortical dementia. Cortical dementias
tend to cause problems with memory, language, thinking
and social behavior (4).
II. Subcortical Dementia:
Dementia affecting parts of the brain below cortex is
subcortical dementia. This type
causes
changes in emotions and movement in addition to problems
with memory (4).
III. Progressive Dementia:
As the name indicates, the dementia that worsens over a
period interfering with cognitive abilities is called
progressive dementia.
IV. Primary Dementia:
Primary dementia does not result from any other disease
for example: Alzheimers disease.
V. Secondary Dementia:
Dementia caused due to a physical disease or injury is
called secondary dementia (4).
Other types of dementia that fall into more than one
of the above types are as follows:
1.
Alzheimer's Disease:
Alzheimer's disease is the
most common form of dementia affecting 10% of the
people above 65 years of age and 50% people over
85. The disease is caused due to irreversible
progressive deterioration of brain cells,
especially the cerebral cortex and hippocampus,
causing loss of cognitive functions such as
memory, movement coordination, pattern
recognition, judgment and reasoning (5).2.
Vascular Dementia:
Vascular Dementia is the second most common cause
for dementia accounting for about
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20% of all cases. Damage to the brain due to
cerebrovascular or cardiovascular strokes are the main
causes. Vascular dementia has 3 subtypes with varying
causes and symptoms.
1). Multi Infarct Dementia (MID):
MID is caused by a number of small strokes leading to
multiple damaged areas and lesions in the white
matter or nerve fibers of the brain. It is important
to note that
not all strokes cause
dementia, in some cases a single stroke can damage
the brain enough to cause dementia. (4)
Dementia from a single stroke damages either the left
side of the brain or hippocampus and is called single
infarct dementia.
2). Binswangers Disease:
It is a rare type of dementia caused by damage to
small blood vessels in the white matter of brain.
People suffering from this disease have abnormal
blood pressure, stroke, blood abnormalities, disease
in the large blood vessels of the neck and/or disease
of the heart valves. The disease leads to lesions in
the brain, memory loss, disordered cognition and
changes in mood. Symptoms such as urinary
incontinence, difficulty in walking, clumsiness,
slowness, lack of facial expression and speech
difficulty are prominent.
3). CADASIL:
Vascular dementia of this type is a rare hereditary
disorder abbreviated as Cerebral Autosomal Dominant
Arteriopathy with SubCortical Infarct and
Leukoencephalopathy. CADASIL is linked to
abnormalities of a specific gene, Notch3, which is
located on chromosome 19 (4). CADASIL
causes strokes with multi-infarct dementia, migraine
with aura and mood disorders.
Vascular dementia may also be caused due to
inflammation of the blood vessel system (Vasculitis),
low blood pressure and lesions due to brain
hemorrhage.
3. Lewy Body Dementia (LBD):
Lewy Body Dementia (LBD) is caused due to the death of
cells in the brains cortex and part of the
mid-brain (Substantia nigra) with many remaining
mid-brain nerve cells containing abnormal structures
called Lewy bodies. A protein called alpha-synuclein
contained in these Lewy bodies causes several disorders
collectively called Synucleinopathies.
Symptoms of LBD overlap with those of Alzheimers
disease and typically include visual hallucinations,
parkinsonian symptoms and day-to-day fluctuations in the
severity of symptoms.
4. Frontotemporal Dementia (FTD) or Frontal
Lobe Dementia:
FTD is a group of diseases caused by the degeneration of
nerve cells in the frontal and temporal lobes of the
brain. There is an abnormal formation of tau protein in
these regions of the brain accumulating into
neurofibrillary tangles and disrupting normal cell
activities, thus ultimately leading to death of cells.
People suffering from FTD do not maintain normal
interactions and follow social conventions. Other
symptoms such as loss of speech, language, compulsive or
repetitive behavior, increased appetite and motor
problems (stiffness and balance) are common in FTD.
Picks disease is a
type of FTD in which the nerve cells are composed of Pick
bodies containing the protein tau inside the typically
swollen or ballooned neurons. The symptoms of the disease
include inappropriate social behavior, loss of mental
flexibility, language problems and difficulty in thinking
and concentration.
Primary progressive aphasia (PPA) is also one of the
types of FTD that develops on people in their early
forties. In PPA, one or more of the functions such as
deficit in language, speaking, understanding and naming
common objects are gradually impaired over a period time.
Many, but not all, people with PPA eventually
develop symptoms of dementia (4).
5. HIV-Associated Dementia (HAD):
As the name indicates, HAD is due to an infection of
human immunodeficiency virus (HIV) destroying the
brains white matter ultimately leading to dementia.
The symptoms include impaired memory, apathy, social
withdrawal, difficulty in concentrating and movement.
6. Huntingtons Disease (HD):
It is a hereditary disorder caused by a faulty gene for
protein Huntington leading to degeneration of many
regions of brain and spinal cord. Symptoms of the
disorder appear in patients aged 30 to 40 years with
average life expectancy being about 15 years. Symptoms of
the disease include mild personality changes,
irritability, anxiety, depression, psychotic behavior,
chorea, arrhythmic movements of the body, muscle
weakness, clumsiness, gait disturbances and progress to
severe dementia.
7. Dementia Pugilistica or Chronic Traumatic
Encephalopathy or Boxers Syndrome:
Dementia due to head trauma caused by head injury during
boxing is called Dementia Pugilistica. Common symptoms
such as dementia and Parkinsonism appear many years after
the trauma. Other common symptoms include poor
coordination and slurred speech. A single
traumatic brain injury may also lead to a disorder called
post-traumatic dementia (PTD) (4).
8. Corticobasal Degeneration (CBD):
CBD is a progressive disorder marked by loss of nerve
cells and
atrophy of multiple areas of
the brain (4). Symptoms include poor
coordination, rigidity, memory loss, dementia,
visual-spatial problems, apraxia (i.e., loss of the
ability to make familiar, purposeful movements), hesitant
and halting speech, myoclonus (i.e., involuntary muscular
jerks) and dysphagia (i.e., difficulty in swallowing).
Generally, death occurs due to secondary problems such as
pneumonia, sepsis, pulmonary embolism etc.,
9. Creutzfeldt-Jakob Disease (CJD):
This is a rare, degenerative, fatal brain disorder
affecting one person in one million every year worldwide.
CJD is believed to be caused due to an abnormal form of
protein named prion. Symptoms include problems with
muscular coordination, personality changes, impaired
memory, judgment and thinking, impaired vision, insomnia,
depression and myoclonus. Finally, the patients may die
due to Pneumonia and other infections.
Other rare hereditary dementias include
Gerstmann-Straussler-Scheinker (GSS) disease, fatal
familial insomnia, familial British dementia, and
familial Danish dementia (4).
Dementias in Children
Some disorders can lead to dementia in children, which
include:
A. Niemann-Pick Disease:
It is a group of inherited disorders affecting the
metabolism caused due to
specific genetic
mutations (4). Patients suffering from this
disorder cannot metabolize cholesterol and other lipids
leading to accumulation of excessive cholesterol in the
liver and spleen and excessive lipids in the brain.
Symptoms of the disorder are dementia, confusion and
problems with learning and memory.
B. Batten Disease:
It is a fatal, hereditary disorder of the nervous system
leading to an accumulation of lipopigments in the
bodys tissues. Ultimately, children with this
disorder develop dementia, blindness and become
bedridden. Symptoms of the disease are personality and
behavioral changes, slow learning, clumsiness, stumbling,
mental impairment, seizures and progressive loss of sight
and motor skills.
C. Lafora Body Disease:
It is a rare genetic disorder leading to seizures, rapid
progressive dementia with movement problems. Lafora
bodies are microscopic structures present in the brain,
skin, liver and muscles of the affected children.
Other disorders that include symptoms of dementia are
mitochondrial myopathies, Rasmussen's encephalitis,
mucopolysaccharidosis III or Sanfilippo syndrome,
neurodegeneration with brain iron accumulation,
leukodystrophies such as Alexander disease, Schilder's
disease and metachromatic leukodystrophy (4).
See Also:
Dementia:
Introduction
Dementia: Types
Dementia:
Causes & Risk Factors
Dementia: Signs &
Symptoms
Dementia: Stages
Dementia: Medical Tests
& Diagnosis Methods
Dementia:
Treatment & Prevention Options

Article by Kona Vishnu, MS
Medical Writer,
OmniMedicalSearch.com
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