Brain Atrophy - ️️Severe shrinking of the entire cortex
Severely enlarged ventricles
Severe shrinkage of hippocampus
Rate of neuronal loss accelerates as the disease progresses
Whole brain weight decreased by 10% to 19%
Not evenly distributed
Mostly in gyri of association areas
Relativel...
OCCTH 585 - Alzheimer's Disease
Brain Atrophy - ✔️✔️Severe shrinking of the entire cortex
Severely enlarged ventricles
Severe shrinkage of hippocampus
Rate of neuronal loss accelerates as the disease progresses
Whole brain weight decreased by 10% to 19%
Not evenly distributed
Mostly in gyri of association areas
Relatively less: primary motor, primary somatosensory and primary visual cortices
-- Mostly the medial temporal lobe is affected --
- If it is purely AD, motor and sensation normal
Top 9 Early Signs - ✔️✔️1. Memory loss
2. Changes in mood
3. Misplacing belongings
4. Hard to complete familiar tasks
5. Confusion of time nd place
6. Social withdrawal
7. Poor judgement
8. Struggling to communicate
9. Changes in vision
Alzheimer's disease - ✔️✔️One of the most common types of dementia. Not a process
of accelerated brain aging. Specific characteristics in neurons.
- Insidious onset
- cognitive and behavioural impairments
Neuropathology - ✔️✔️- Dedriditc modicfication
Normal aging - degenerative changes in dendrites of pyramidal neurons
Normal Adults - ✔️✔️Also develop plaques:
- Neuritic (senile) plaques (not strictly intraneuronal)
- Around late 80s
- Amount much less than AD
- Very few neurofibrillary tangles (entirely intraneuronal, lead to death of neuron)
, Density of Plaques - ✔️✔️- Temporal lobe is most severely affected
- Hippocampus volume is reduced by up to 60% in advanced AD
- Reduced connectivity of the hippocampus with other brain regions
β-amyloid plaques - ✔️✔️Defective breakdown of a benign substance known as
amyloid precursor protein (APP)
Produce sticky, insoluble shards of β-amyloid plaques
- stick together, form dense plaques, damage axons, lead to development of
neurofibrillary tangles
Neural systems for AD - ✔️✔️Limbic System:
- Impacts our behaviout
- Plays a role in basic instincts such as sleping and eating
- Plays a role in emotions
- impacts sense of smell
- The hippocampus, which is part of the limbic system, is important for learning and
short term memory - the part of the brain where short-term memories are converted to
long-term memory for storage - also where verbal and visual memory are processed
Circadian rhythms are affected (day-night cycle)
Suprachiasmatic necleus within the hypothalamus (circadian clock)
Neurotransmitter abnormalities - ✔️✔️Tracks form by cholinergic neurons (containing
acetylcholine) are destroyed
Nucleus basalis has projections to cortical areas, volume reduce by ~70% in AD
Facts about AD - Sporadic - ✔️✔️90% of AD is late onset, around 65, no known
genetic cause
Facts about AD - Familial - ✔️✔️10% of AD, Genetic mutations, Usually early onset
Facts about AD - Age - ✔️✔️Risk doubles every five years after the age of 65
Facts about AD - History of Head Injury - ✔️✔️Speculated to increase the neuronal
secretion of amyloid
History of depression
History of electroconvulsive therapy (ECT)
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