Pharmacology Flashcards
What are the 4 types of dementia?
Alzheimer’s
Fronto-temporal
Vascular (unusually associated with damage)
Dementia with Lewy bodies (associated with Parkinson’s disease)
What are the characteristics of frontotemporal dementia?
- associated with early onset dementia
- global cognitive impairment and motor deficits with are fatal with death occurring after around 8 years after symptom onset
- symptoms: progressive deterioration of behaviour with behavioural disinhibition, loss of sympathy and empathy, compulsive/ritualistic behaviour, dietary changes (e.g. consumption of inedible objects, altered food preferences)
What are the characteristics of dementia with Lewy bodies? (DLB)
- characteristics shared between Alzheimer’s Disease and Parkinson’s disease
- formations of Lewy bodies containing alpha-synuclein thought to originate within the brain stem, progressing ti the limbic system and cerebral cortex
- symptoms: dementia and delirium-like changes in cognition, visual hallucinations, rapid eye movements
Characteristics of vascular dementia?
- Associated with demographic, genetic, atherosclerotic and stroke relative risk factors
- Pathological hallmark; not yet determined due to variable cognitive impairment that is less sensitive to cognitive tests
- Symptoms: varies memory impairment
What are the macroscopic pathology features of Alzheimer’s Disease (AD)?
- Moderate cortical atrophy within cortex and limbic system
- Enlarged frontal and temporal horns of the lateral ventricles
- Widening of sulcal spaces and narrowing of gyro compared to normal brain
What are the microscopic pathology features of AD?
-Amyloid plaques- Formed from accumulation of Abeta40 and Abeta42
Abeta42 is prominent and dominant in the formation of amyloid plaques in AD
These plaques are associated with neuronal loss and cognitive decline
- Neurofibrillary tangles: composed of filamentous tau protein. In AD tau proteins are hyperphosphorylated and abnormally folded, leading to loss of tau function - compromised normal tau protein leads to the spread of tau pathology in the AD brain
Which allele of apolipoprotein E (APOE) is associated with AD risk?
E4
- around 3 fold risk if inherit one cope of e4 (APOE4 heterozygous)
- around 15 fold risk if inherit 2 (homozygous APOE4)
What are the 4 symptomatic treatments of dementia?
- Augmenting the cholinergic pathways - e.g. cholinesterase inhibitors
- NMDA receptor antagonists
- Management of behavioural and psychological symptoms - pharmacological and non-pharmacological
- Palliative care at end stage disease
How do acetylcholinesterase inhibitors work in treating dementia?
Block eat erase-mediated metabolism of ACh to choline and acetate which results in increased ACh availability for postsynaptic and presynaptic nicotinic and muscarinic ACh receptors
How do glutamate modulators (NMDA a N-methyl-D-Asperate) receptor antagonists work?
Memantine
Replacement of glutamine in NDMA receptor binding which reduces AD symptoms and disease
Used as an alternative to ACHE inhibitors due to intolerance or counter indications
What is a seizure?
A transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain
- Clinical manifestation
- Discorded and hypersynchronised discharge
- In a network of cerebral neurons
What is epilepsy?
A pathological and enduring tendency to have recurrent seizures and by the neuro-biological, cognitive, psychological, and social consequences of his condition
What are the two main types of seizure?
- Generalised seizures - starts simultaneously in both hemispheres
- Focal seizures - seizure starts in a focus and then spreads
What are the common generalised seizures?
Typical absence, myoclonic, tonic-clonic
Describe a myoclonus seizure
Sudden, brief, shock-like muscle contractions. Usually bilateral arm jerks and often worse in mornings. Precipitated by sleep deprivation and alcohol
Describe tonic-clonic seizures
Sudden onset, gasp, fall. Tonic phase with cyanosis (lips go blue). Clonic phase and a post ictal phase (altered state of consciousness after an epileptic seizure). Tongue bitten and incontinence, noisy breathing, headache and muscle pain afterwards
What are the uncommon generalised seizures?
Atypical absence, tonic, atonic (usually associated with severe epilepsy
Describe focal seizures
Focal onset - often aura or “warning” at onset
As seizures spreads - loss of awareness and involuntary movement
Often caused by brain lesions
Describe temporal lobe seizures
Auras- rising sensation in stomach, olfactory and gustatory hallucinations (smell or taste), déjà vu
As seizure spreads - suddenly stops and blank stares, loss of responding and awareness, mouth movements, fidgeting or postures, automatisms (nonpurposeful, stereotyped, and repetitive behaviours following a seizure)
What can epileptiform discharges be due to?
- Neuronal bursting (an ion channel property)
- Synaptic effects (both glutamate and GABA)
- Glia effects
- Non-synaptic effects (e.g. extra cellular K+)
What changes occur in the epileptogenesis model?
Structural: Cell loss inhibitory (interneurons) - disinhibition circuits
Axonal sprouting - extra excitatory circuits
Neurogenesis
Gliosis (glial reaction in response to damage)
Neuro-inflammation
Molecular: neuronal channels (Na, K, Ca, Cl, HCO3-) “acquired channelopathy”
Receptors - GABA, AMPA, NMDA, ACh
Neurotransmitter transporters
Neuro-modulators (peptides + endocannabinoids)
Functional: gap junctions, glia: buffering of extra cellular environment
Blood brain barrier breakdown
What activity occurs in the prefrontal cortex?
Intellectual function; emotional behaviour (suppresses aggressive behaviour
What activity occurs in the motor cortex?
Contains the premotor and primary motor cortex
Which part of the brain governs the sleep-wake cycle?
The suprachiasmatic nucleus (SCN) present within the hypothalamus
What happens during non-REM sleep (NREM)?
Restful and restorative
Stage 1: transition from awake to sleep
Stage 2: initiate ‘true’ sleep
Stage 3 and 4: deep sleep
What happens during REM sleep?
Consolidate and integrate memories
Development of CNS
Presents with burst of rapid eye movements
Other physiological processes
Name 5 neurochemical systems that promote arousal
- Ach: forebrain and brainstorm, active during wakefulness and REM sleep
- NA/NE: generate arousal ‘fight/flight response’
- Histamine: promotes wakefulness; reducing REM & NREM
- 5-HT: promotes wakefulness and suppresses REM sleep
- DA: exerts potent wake promoting effects
Name 5 types of sleep disorders
- Rapid eye movement disorder
- Restless legs syndrome
- Periodic limb movement of sleep
- Insomnia
- Excessive daytime sleepiness
What are the symptoms and potential causes of restless leg syndrome?
- uncomfortable feeling in the legs and feet (itchy, twitchy, throbbing etc)
- powerful urge to move legs to reduce the uncomfortable feeling
- worsening at night when lying or sitting
Causes: dopamine dysfunction, genetics, medications, chronic illness, vitamin and mineral deficiency (B12, magnesium), pregnancy (3rd trimester), sleep deprivation
What is multiple sclerosis?
Demyelinating disease, autoimmune disease, inflammatory disease
Immune cells attack myelin - inflammatory response - myelin debris accumulates in lesions with causes and immune response
What and the genetic and environmental factors that lead to MS?
- Autoimmune diseases more common where people don’t experience extreme hunger
- family link increases odds by 40%
- 2-3 fold increased prevalence in women
- Caucasian/ northern hemisphere bias
- triggering infection (similar antigen?)
- vitamin D deficiency
What are the 4 types of MS?
- Relapsing Remitting MS (RRMS) - most common (85% of cases). Discrete attacks that evolve over days or weeks followed by some degree of recovery over weeks or months. In between attacks the patient has no worsening neurological function
- Secondary progressive MS (SPMS) - initial relapse followed by gradual neurological deterioration not associated with acute attacks
- Primary progressive MS (PPMS) - steady functional decline from the onset of the disease. No relapses ever
- Progressive relapsing MS (PRMS) - steady functional decline from onset of the disease with later superimposed acute attacks. PRMS and PPMS cannot be distinguished during early stages, until relapse occurs
What is the autoimmune cascade at MS lesions?
- microglia an/or macrophages erroneously respond to myelin basic protein as an antigen
- Local innate immune response (release cytokines, pro-inflammatory mediators, and cytotoxic agents such as superoxide and nitric oxide)
- Antigen presenting cells recruit T cells and B cells from circulation
- Full immune response involving complement, antibodies, cytokines and chemokines
- microglia and astrocytes isolate lesion via reactive gliosis
- Anti-inflammatory T cells terminate the response
- Episode (hopefully) resolves
What happens when the membrane depolarises?
Depolarization opens sodium ion channels (fast)
Sodium ions flood into the cell down its electrochemical gradient
This depolarizes the membrane even more
How is the membrane repolarised?
potassium ion channels open (more slowly) and flood out of the cell down its electrochemical gradient.
Sodium ion channels inactivate preventing further depolarisation
This repolarises the membrane
What are the symptoms of MS?
Disrupted vision Tingling, numbness, pain Muscle spasm or weakness (speech impairment) Loss of coordination Loss of bladder/bowel control Fatigue Cognitive impairment Mood changes Can lead to severe disability
What treatments can be used? (3 approaches)
- Manage the symptoms ( visual: gabapentin, ophthalmological treatments. Muscle spasms/stiffness: baclofen, gabapentin, diazepam. Pain: gabapentin, carbamazepine, amitriptyline and physiotherapy and lifestyle changes)
- Speed recovery during relapse (high dose corticosteroids e.g. methylprednisolone to supress inflammatory response and speed resolution of relapse episode)
- Slow the progression (disease-modifying therapies - immunomodulating drugs and biologics work by suppressing autoimmune response e.g. beta interferons, glatiramer acetate, fingolimod, ocrelizumab, alemtuzumab, cladribine, dimethyl fumarate, haematopoietic stem cell transplantation aka chemotherapy)
Explain how beta-interferons work
- cytokines released from fibroblasts as part of antiviral immune response
- inhibit activation and migration of T cells
- suppress the release of pro-inflammatory cytokines
- slows disease progression
- subcutaneous or intramuscular dosing
- decreases frequency and severity of relapses