Cognitive Disorders Flashcards
Specific Disorders
Resulted from focal damage to the brain
— injuries caused by bullets, strokes
Generalized Disorders
More distributed effects on brain tissue, breakdown is not restricted to one domain, multiple cognitive abilities are affected simultaneously
— closed head injuries, dementias, demyelinating diseases
Closed Head Injury
- Brain sustains damage when the head forcefully comes into contact with another object (but object does not penetrate the brain)
— leading cause of TBI (traumatic brain injury)
Acceleration-Deceleration Injury
Primary mechanism of damage in closed head injury
Damage from rapid acceleration of the head followed by sudden deceleration
Focal damage due to the impact of the brain on the skull
Diffuse damage due to twisting and shearing of neurons
Neurons most vulnerable to twisting are those in white-matter tracts, which have long axons and connect distant brain regions
Consequences of Acceleration-Deceleration Injury
Secondary biochemical effects include glutamate excitotoxicity which can cause cell death
Disease state lasts beyond initial incident. Can appear as:
– Enlargement of the ventricles
– Loss of volume in large myelinated tracts
Longitudinal studies indicate white-matter deterioration continues for several years following TBI
Focal Injuries: Coup and Contrecoup
Focal damage at site of impact: coup injury
Focal damage opposite of site of impact: contrecoup injury
Glasglow Coma Scale
— Prominent clinical sign of a closed head injury is a significant alteration in consciousness
— The coma scale:
——- Provides a method for classifying the severity of damage in the brain
——- Evalulates: visual responsiveness, motor capabilities, verbal responsiveness
(check slides for chart and recovery prediction)
Head Injury Consequences
– All types can impact mental functioning
—- mild traumatic Brain Injury (mTBI) = concussion
– Attention and executive functioning often affected by closed head injury
-Posttraumatic Amnesia
— Varies from an inability to learn new info to an inability to report basic info
Long Term Consequences of a brain injury
Sustaining a closed head injury:
— Raises risk for sustaining another injury
— raises the risk for additional neurological consquences in the future
— associated with posttraumatic epilepsy, which may begin over a year after the head injury
— May put the individual at the risk of dementias
Interventions for Closed Head Injury
Preventions and Interventions
- Prevention: safety protections, violence prevention
- Pharmacological treatments to lessen biochemical cascade effects like excitotoxicity and inflammation
- Interventions can specifically target the cognitive level
Dementia
Syndrome involving loss of cognitive functions, sometimes accompanies by personality changes, that interferes with work or social activities
Progresses in stages (mild, moderate, severe) that lead to death
3 varieties
— Cortical Dementia
— Subcortical Dementia
— Mixed-Variety Dementia
Cortical Dementias
- one of three varieties (cortical, subcortical, mixed-variety)
- Manifest as the co-occurence of specific cognitive deficits such as aphasia, apraxia, agnosia, spatial/ calculation deficits, memory problems
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Alzheimer’s disease
Frontotemporal Dementia
Subcortical Dementias
- one of three varieties (cortical, subcortical, mixed-variety)
- Result in general cognitive deficits (rather than specific)
Mixed-variety Dementias
- one of three varieties (cortical, subcortical, mixed-variety)
- include aspects of both cortical and subcortical dementias, midway between cortical and subcortical
- specific deficits + general deficits
Cortical Dementia: Alzheimer’s Disease
Defined by a decline in memory and other aspects of cognitive functioning, including at least one of the following: language, visuospatial skills, abstract thinking, motor performance, and judgment.
Also see emotional dysfunction and personality changes, which tend to worsen over time.
Two subtypes:
— Early-onset AD: onset occurs before the age of 65; progresses rapidly
— Late-onset AD: onset after the age of 65; slower cognitive decline
AD diagnosis
Alzheimer’s
Based on behaviour and cognition
—– The defining biological characteristics can only be determined by post-mortem examination of brain
—– A probable diagnosis is made when other causes of dementia are ruled out and the person’s behavioral pattern is consistent with the disease
Research has focused on potential biomarkers to serve as additional indicators of disease presence
AD Symptoms
Alzheimer’s patients have an inability to acquire new information as a result of severe, global anterograde amnesia
— People with AD remain in familiar areas, reducing the need to acquire new information
Widespread amnesia impacts procedural knowledge and implicit learning as well as working memory
— More aspects of memory are affected because more brain regions are affected, including cortical regions
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AD patients can also experience difficulty/decline in:
—- Language: verbal fluency, semantic aspects of language
—- Visuospatial processing
—- Conceptual aspects of motor behavior
—– Executive functioning
—- Changes in emotional functioning and personality
Varies from person to person, as the disease becomes more global, becomes more impaired
Neurobiological characteristics of AD
Seen in greater levels in AD brains:
Neurofibrillary tangles- thought to interfere in with neurons/ cognition, twisted pairs of helical filaments found within the neuron.
Amyloid plaques
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unsure if they cause AD, or if AD produces an increase in them
Amyloid Plaques
- Deposits of aluminum silicates and amyloid peptide that create a conglomeration of proteins
- typically surrounded by neurofibrillary tangles, believed to cause vascular damage and neuronal cell loss
PET methods have made it possible to assess the presence of amyloid plaque in a living person
Progressive accumulation of amyloid plaques is correlated in cognitive decline in living AD patients
Advanced AD and Neuron loss
Accumulating tangles and amyloid plaques result in loss of synapses and cells
In later stages, cell loss is visible on anatomical brain images; cortex is atrophied, ventricles enlarged
Distributed across frontal, anterior temporal, and parietal cortex
Subcortical structures affected include hippocampus, amygdala, and olfactory system