Chapter 15 PSYB64
Soccer players perform worse on tests for attention, memory, and planning compared to swimmers and
o Sortland and Tysvaer (1989) using CT found that 1/3 of former Norwegian national soccer
members had cerebral atrophy.
o Most likely the source of injury is from “heading” the ball.
o It is reported that the greatest cognitive deficits occurred among players who headed the ball
Brain is protected by skull bones/meninges, cerebrospinal fluid (CSF), and blood-brain barrier. Damage
can occur due to interruptions in the blood supply and head injuries.
Cells in nervous system (NS) rely on oxygen which is supplied by rich network of blood vessels
o Circulation of blood to neural tissue can be ruptured/blocked and that can cause serious damage
Stroke – type of brain damage caused by an interruption of blood supply to the brain by bleeding or
blockage of blood vessel.
o Risk factors of stroke – age, hypertension, smoking, diabetes, high cholesterol, obesity, alcohol
use, cocaine, amphetamines, heroin, and other drugs
o Atherosclerosis also increases risk of stroke when arteries are narrowed/hardened
Cerebral hemorrhage (Bleeding in the brain)– Condition caused by bleeding in the brain.
o Generally results from hypertension (high blood pressure) or structural defects in arteries serving
o Sometimes occur due to rupture of aneurysms –balloon-like bulge in walls of arteries
o Can occur due to blood diseases such as leukemia or exposure to toxic chemicals.
o Usually fatal because of brain damage produced by blocking blood supply to neurons and
flooding areas of brain with salty blood that dehydrates and kills nearby neurons
Ischemia (low oxygen level) – Blockage of blood vessels result in ischemia. It is condition where
inadequate blood flow results in insufficient quantities of oxygen being delivered to tissue.
o Cases of Ischemia account for 80% of all strokes.
o Can result in neural tissue death in an area called infarct – can causes changes in consciousness,
sensation, ability to move (depends on their size and location)
o Transient ischemic attacks (TIAs) – produces brief (less than 24 hours) episode of stroke
symptoms that doesn’t cause permanent damage. They are strong predictors of subsequent
When an area of the brain is deprived of oxygen for a sufficient amount of time, cells begin to die. The
area of dead tissue is referred to as an infarct.
Material causing blockage of a blood vessel can be classified as either a thrombosis or an embolism.
Thrombosis –A plug of blood or other material that blocks a blood vessel without from its point of origin.
Embolism – A plug that passes into smaller and smaller blood vessels until it forms a blockage.
o Blockages in small blood vessels are less damaging than in large arteries serving the brain but
multiple small strokes can cause significant damage.
Cells in middle layers of cortex and hippocampus are most vulnerable to ischemia. It isn’t only lack of
oxygen that caused cell dead, there are other processes involved in brain damage caused by ischemia.
Excitotoxicity – coined by John Olney to describe ability of excess glutamate to kill neurons
o Now believe that cell death after a stroke is caused by excess glutamate activity triggered by lack
o Excess glutamate in neuron initiates cascade of events leading to cell death
o In response to unusual amounts of glutamate, abnormal calcium activity in the cell stimulates 4
‘executioner’ enzymes that damage cell’s energy stores, membranes, cytostructure, and DNA Chapter 15 PSYB64
To reduce risk of stroke = surgery, reduce formation of thrombosis and emboli, as well as reducing blood
Penumbra = areas of tissue surrounding an infarct. Although some cells die immediately following a
stroke, medical attention can save many other neurons and glia in ischemic penumbra.
Traumatic brain injuries – result of physical damage to the brain
o Usually caused by traffic accidents, gunshot wounds, falls
Divided into 2 categories:
o Open head injuries – penetration of skull
Usually because of gunshot wound or fractures of skull where bone fragments can
enter the brain
Most fatal when damage is caused in ventricles, both hemispheres, or multiple lobes in
o Concussions/closed head injuries – occurs because of blows to the head or to the body that
causes “impulsive” force transmitted to brain
Can be mild – no loss of consciousness or for only a brief time
Can be severe – coma
Can cause physical, behavioural, and cognitive problems that lasts for months or can be
Concussions produce damage in several ways *Figure 15.4*
o Coup – damage to brain where blow to the head occurs
Can cause damage by compression of the skull against neural tissue
o Countercoup – damage to brain on the opposite side of blow because force of the blow pushes
brain against the skull opposite the coup
Severe coup/countercoup can be have subdural hematoma = mass of clotted blood (like bruise) that
forms between dura mater and arachnoid after head injury
White matter damage can occur due to twisting of the brain within the skull in response to blow
Pressure exerted on brain because of welling of injured tissues can cause damages or interruptions in
Post-concussion syndrome (PCS) – set of symptoms that follow concussion for period of days to years –
headaches, cognitive deficits, emotional changes, etc. It can occur in some but not all cases of
o Cognitive deficits = lack of concentration, reduction in processing speed, deficits in higher-order
cognitive functions (memory, attention)
o Physical symptoms = headache
o Emotional changes = depression, irritability, etc.
o Persistence of PCS correlated with damage in brain structures such as white matter (corpus
callosum and fornix) and gray matter = upper brainstem, base of frontal lobes, medial temporal
Repeated mild head injuries like in athletes can still be damaging
Dementia pugilistica (Boxer’s syndrome)= severe form of chronic traumatic brain injury often seen in
boxers due to repeated blows to the head over the course of their careers.
Chronic traumatic brain injury (CTBI) –type of brain damage caused by repeated concussions.
o Associated with slurred speech, memory impairment, personality changes, lack of coordination,
o Shows similar patterns of degeneration like in Alzheimer’s
o Boxer George Foreman is an example of a person who escaped CTBI. Boxers who carry the E4
variant of APOE are more likely to develop CTBI because it makes them more vulnerable to
negative effects of brain injury. They found that boxers who had E4 variant and had participated
in more than 12 professional bouts had greater neurological damage than those who didn’t carry
E4. Chapter 15 PSYB64
Athletes and Post-Concussive Syndrome: When Is It Safe To Play?
American Academy of Neurology has provided a grading system coupled with recommendations for
returning to play.
Grade 1 concussion – No loss of consciousness, concussion symptoms lasting less than 15 minutes – may
return to play after 15 minutes without any symptoms.
Grade 2 concussion – No loss of consciousness, concussion symptoms lasting more than 15 minutes – the
athlete should have one week without any symptoms prior to returning to play.
Grade 3 concussion – Loss of consciousness for any duration – if it lasts seconds then athlete may return
to play after one week without symptoms. If loss of consciousness lasts minutes or more than two weeks
must pass before the athlete returns to play
Colorado Medical Society and others do recommend termination of a season following Grade 3
Tumours – independent growth of tissues that lacks purpose. Tumors are seen mostly in uterus (1) and
o Usually don’t grow from mature neurons because these cells don’t replicate
o Most brain tumours arise from glial cells and cells from the meninges
o Can form in cells lining ventricles
Malignant tumours – type of abnormal cell growth, lacking boundaries, that invades surrounding tissue
and is very likely to recur after surgical removal
Metastasis – migration of cancerous cells from one part of the body to another
o Malignant tumours shed cells that travel to other areas of body and form new tumours
Tumours that originate in brain rarely metastasize and when they do, the shed cells travel through CSF to
other parts of NS (not through blood stream)
Benign tumours – abnormal cell growth that develops within their own membrane and is unlikely to recur
after surgical removal (because they’re contained within own membrane)
o Don’t metastasize but can still be harmful
o If benign tumor is located in areas where it can’t be removed – it can be as life threatening as
Symptoms of tumours:
Symptoms arise due to increased pressure within the skull once the tumors have attained sufficient size.
o Symptoms are headache, vomiting, double vision, reduced heart rate, reduced alertness, seizures
o Specific disruptions can also occur depending on tumor’s location (e.g. tumors in frontal lobe
causes changes in emotionality and ability to plan or tumor of occipital lobe would affect vision)
Types of tumours:
Identified according to tissue they arise from
o Gliomas – tumours that arise from glial cells and account for 45% of brain tumours