PSYC 301 - Causes of Brain Dysfunction M1

why are blood vessels important

our brain is metabolically active and is supported by a complex vasculature 

our brain is 2% of our body’s weight but…

but receives 15% of cardiac output

what is the brain highly vulnerable to

• disturbances in blood supply

• seconds can lead to neurological symptom 

• minutes can lead to irreversible damage 

where do cerebral arteries supply to 

specific territories

where does the anterior cerebral artery supply blood to

frontal lobe and medial portions of cortex

where does the middle cerebral artery supply blood to

middle portion of brain, cortex

where does the posteriro cerebral artery supply to

more posterior regions

what is used for the mapping of blood vessels in the brain

angiogrpahy

stroke

• neurological symptoms or signs resulting from diseases involved blood vessels

• interruption in blood supply, causing death of tissue 

following a stroke, what are the two regions the affected brain tissues are split into

• infarct

• penumbra

infarct 

dead or dying tissue 

penumbra (3)

• dysfunctional area surrounding the infarct, tissue may either recover or die

• tissue starts to be affected but fate don’t decided yet 

• area of interest when intervention is done

consequences of strokes (5)

• memory (amnesia) 

• language (aphasia) 

• motor function (paralysis) 

• consciousness 

• numbness 

stroke risk factors (6)

• high blood pressure

• high cholesterol

• diabetes

• smoking and vaping

• existing cardiovascular condition

• psychosocial stress

how does high blood pressure increase stroke

increase in pressure and force on vessels walls 

how does high cholesterol increase stroke

blood carrying more fat and can accumulate and block vessel 

how does diabetes increase stroke

poor control of sugar in blood leads to high glucose levels which can accumulate damage to blood vessels, stiffening blood vessels and interact with fats

how does smoking and vaping increase stroke

causes inflammation

how does psychosocial stress increase stroke

• lack of access to quality food 

• inadequate public health education 

• experiences of discrimination 

what are the 2 types of stroke 

ischemic and hemorrhagic 

ischemic stroke

blockage of blood vessels

what are the 3 types of ischemic stroke

• thrombosis

• embolism

• arteriosclerosis 

thrombosis

occlusion due to blood clot or other substances that develops locally

embolism

• results from a moving thrombus that originated somewhere else and travelled to the brain

• high risk after surgery

where can thrombosis and embolism occur

in both arteries and veins and clots can be blood cells, tumour or fats 

arteriosclerosis

• thickening, hardening and narrowing of arteries due to fatty plaque build up 

• correlated to high cholesterol 

can the stroke types interact

yes

damage to brain due to ischemic stroke (3)

• symptoms can take awhile to develop

• some brain areas are more vulnerable (e.g hippocampus)

• multiple mechanisms of damage at a molecular level

what are the multiple mechanisms of damage at a molecular level (4)

• excitatoxicity

• cell death signalling

• oxidative stress

• neuroinflammation

excitatoxicity

excessive glutamate is released by injured neurons, activating receptors on the post synaptic cell, triggering processes in the post synaptic cell that are pathological 

cell death signalling 

cells may be triggered to go in an existing death pathway (apoptosis), all cells have this pathway 

oxidate stress

when cells are injured, they release reactive oxygen species causing damage neuron or surrounding neuron

neuroinflammation

cells dying, triggering more microglia to manage what’s happening which can cause pathological processes as well 

transient ischemic attack (TIA)

• interruption of blood flow causing neurological symptoms but no lasting brain damage, no death of tissue

• but highly predictive of future stroke 

haemorrhagic stroke  

bleeding from a vessel 

where can a haemorrhage occur

can occur in many parts of the brain and symptoms can vary

before a stroke occurs, what develops gradually

aneurysm

aneurysm

weakened vessel wall

how does an aneurysm develop (3)

• congenital or may develop from high blood pressure or accumulated damage

• present in the arteries 

• often an incidental finding 

can an aneurysm be symptom free

yes

2 types of aneurysm treatment

clipping and coiling

clipping

• applied to the neck of the aneurysm to stop the blood flow

• more invasive but permanent

coiling

• aneurysm is filled by platinum coil to prevent bursting 

• catheter is used to insert coil

• require imaging guidance

• less invasive but higher rate of occurrence 

what are the possible stroke treatment

• tissue plasminogen activator (tPA)

• therapeutic hypothermia

• many potential drug targets 

tissue plasminogen activator (3)

• through injection and breaks up blood clots

• only for ischemic stroke

• must be done quickly after stroke 

therapeutic hypothermia

• cooling to slow down/ prevent secondary damage

• might slow down recruitment of microglia 

• can be used for both stroke 

what are tumours

• mass of cells growing independently of the rest of the body

• some can be canerous and some arent

types of tumours

• encapsulated tumour

• infiltrating tumour

• benign

• malignant

encapsulated tumour

grow within their own membrane

infiltrating tumour

not self contained, difficult to remove or destroy

benign 

• surgically removable with little risk or further growth in the body 

• often are encapsulated 

malignant

• tend to grow and spread, sometimes due to metastasis

• parts breaks off and travel through the blood to other parts of the body 

meningiomas (4)

• grow between the meninges

• encapsulated

• usually benign tumours

• relative positive prognosis

glioblastomas (5)

• usually located in the cerebral cortex

• infiltrating

• malignant

• less positive prognosis

• more common in children

metastatic tumours (2)

• infiltrating tumours that grow from tumour fragments in other parts of the body 

• commonly originated from breast or lung 

is our body set up to prevent infectin in our brain 

yes 

when bacteria grows in the brain, it can lead to (2)

• inflammation (encephalitis), reflecting microglia activity

• formation of cerebral abscess (pockets of pus)

how can bacteria get into the brain (3)

• enter vis the bloodstream, infections in the ears and sinuses - bacteraemia

• if already in the meninges

• direct penetration, entering due to injury

risk factors for bacterial infection (3)

• weakened immune system

• common in young infants or old adults 

• not having a vaccine is a risk factor 

what is a meningitis 

when bacteria infect meninges producing an inflammation 

what is the treatment for meningitis

antibiotics

what are the symptoms for meningitis

headache, stiff neck etc

what are the long term complications for meningitis

seizures, speech issues, vision loss

what is an example of bacterial infection

syphilis

syphilis (2)

• bacteria that spreads as an STI

• sometimes it is local to one part of the body

what happens if syphilis infects the brain 

can lead to neurosyphilis 

neurosyphilisis

can cause general paresis, mental disorder characterised by delusions and personality changes 

what is the treatment for syphilis

antibiotics

2 types of viral infections

• neurosystem specific

• indiscriminate

neurosystem specific

viruses that tend to target the nervous sytem

what is an example of neurosystem specific virus

rabies

rabies

• transmitted by being bitten by an animal infected with rabies 

• rabies alter behaviours of these animals, making them more likely to bite and pass on virus 

process of rabies infection (2)

• viral particles gets taken up by motor axons, efferent fibres carrying information from CNS to muscles

• if it gets into axons, retrograde transport occurs and goes back into the CNS leading to CNS infection 

what happens once rabies enter the brain

symptoms of lack of energy, headache and fever occurs

in the later stages of rabies infection

pain, depression, inability to swallow, might enter coma, die due to respiratory dysfunction 

indiscriminate

virsuses that affect many systems in the body, including the brain

example of indiscriminate viral infection

• herpes simplex, an STI

• covid 19

covid 19 study (3)

• systematic review done with 1.5 million cases

• most common sysmptoms: anosmia, fatigue, headache

• more common acutely

how does covid-19 occurs (2)

• virus binds to Ace2 receptor that is in the cell membrane of many cells throughout the brain and body

• receptor is involved in how cells regulate BP and inflammation

limitations of the Covid 19 study (3)

• long term effects still unknown

• heterogenous waves - covid 19 has many variants

• who becomes a “case” - those undocumented cases 

parasitic infections 

also called neurocycticerosis: tapeworm in the brain

treatment for parasitic infections

anthihelminthic treatment (anitworm medicine) and treat possible resulting reilepsy

how does parasitic infections occur

result from contact with pigs and fecal matter

neurotoxins

chemicals that are physically damaging to nerve tissue

example of neurotoxins 

mercury 

mercury

can accumulate in the brain and produce a toxic psychosis - symptoms of delusions and hallucinations

what is the stereotype of hat makers

they used mercury to shape the materials to make hats which meant that many of them had this type of psychosis

vaccines are safe (2)

• vaccines have never contained methyl mercury (harmful form)

• before 2001, canadian vaccines contained small amounts of ethyl mercury (not harmful), but now removed due to public’s concern

no link between vaccines and autism (2)

• belief originated with a fradulent study of 12 children who recieved the MMR vaccine (study not retracted)

• enormous loss of time, effort and research money spent disproving this

another example of neurotoxin

lead

lead

• can accumulate in our body over time and exposure can lead to toxic psychosis

• even low levels of lead can affect children’s learning and development

traumatic brain injury

brain injury caused by an outside mechanical force

causes of TBI (4)

• primarily in children and teens, TBI coming from sports and recreational injuries

• throughout life, TBI comes from transport accident

• TBI from falls common in young children and older adults 

• some TBI from assault and struck by object 

common TBI symptoms (5)

• changes in energy, fatigue 

• sensory changes

• memory changes

• coordination issues

• changes in emotions 

when is CTE diagnosed

only diagnosed post mortem based on accumulation of abnormal tau proteins as need to see physical tissue by staining brain

where do abnormal proteins accumulate 

first in the sulci and then small blood vessels 

in a healthy brain

it looks wrinkly

with atrophy,..

sulci becomes exaggerated, looks wider and has less tissue

where is atrophy seen 

in frontal and temporal cortical, atrophy of medial lobe including hippocampus and amygdala 

what is the relationship between abnormal tau severity and atrophy

they are highly correlated but causality is not understood