28 The effect of ageing on the nervous system Flashcards
what is Alzheimer’s Disease?
{a form of dementia}
a reduction in cognitive ability associated with gradual brain cell death
what is familial AD?
a family history of AD attributed to susceptibility
some alleles cause early onset
~ 0.1 % of cases are autosomal dominant inheritance
what are the three alleles that tend to AD mutations?
amyloid precursor protein
presenilin 1
presenilin 2
what are causes of sporadic AD?
other genetic differences (e.g. APOEe4 –> incr. rate of deposition in plaques)
severe/repeated head injury
stroke
low levels of intellectual stimulants
what are some cardiovascular diseases that can contribute to development of AD?
hypertension
smoking + its attributed diseases
high blood cholesterol
what are symptoms of AD in brain scans?
shrivelled/fewer brain cells
shorter/fewer dendrites
Tau inside cells
outline the early stage of AD
cognitive deficits are accounted for ∴ person continues to function independently
basic memory loss; poor judgement; mood changes
outline the mid-stage of AD
personality changes
physical problems
lack of awareness of forgetting
aphasia; disorientation; aggression
outline the late stage of AD
severe and distressing
loss of control of bodily functions –> complete dependency on carer
loss of language and dysphagia
what are Tau proteins?
proteins that stabilise microtubules
abundant in CNS neurones
how do Tau proteins contribute to development of AD?
neurofibrillary tangles of Tau
hyperphosphorylation of Tau –> build up inside the neurone causing them to disintegrate
abnormal breakdown of Tau –> B-amyloid proteins –> accumulates and forms plaque on outside of axons and dendrites
how does a loss of neurones and synapses contribute to development of AD?
in cerebral cortex and subcortical regions
gross atrophy of temporal/parietal lobes + parts of frontal cortex
how does herpes simplex type 1 contribute to development of AD?
causative of APOEe4
causes damage to CNS
outline the inflammatory processes that contribute to development of AD
derivatives of B-amyloid-derived diffusible ligands
kill a range of neurones
bind to surface receptors on the neurones and change the structure of a synapse –> disruption to neuronal communication
how could a vaccine prevent AD?
stimulates B cells
antigen is abnormal part of B-amyloid
immune system acts against the body protein
specific antibodies attach to B-amyloid
removed by white blood cells
what is the difference between age-related memory loss and dementia?
dementia is disruptive to normal functioning
how can memory loss be reduced?
regular exercise
social interaction
fruit/veg/antioxidants
managing stress
sufficient sleep
not smoking
what is presbycusis?
age-related hearing loss due to the damage and death of hair cells in the cochlea and neurones in the auditory nerve
what is visual impairment?
a severe reduction in vision that cannot be corrected with standard glasses or contact lenses and reduces a person’s ability to function at certain or all tasks
what is age-related macular degeneration (ARMD)?
a loss of central vision that results from a loss of effective function in the macular
what is dry ARMD?
cellular debris (drusen) accumulates between retina and choroid causing the retina to detach
what is wet ARMD?
{neovascular}
abnormal blood vessel growth in the choroid causing leaking of fluid into retina –> scarring of macular
retina can detach from choroid
how is wet ARMD treated?
laser coagulation surgery
medication to inhibit blood vessel growth
how do eyedrops cause the pupil to dilate?
circular and radial muscles = antagonistics
drops act like NAdr (symp.)
∴ radial muscles contract
drug also blocks ACh (para.)
∴ circular muscles not stimulated to contract
