Dementia Y2 Flashcards
What are the types of Long term memory?
Explicit and Implicit.
What is explicit memory?
Long term memory category which requires active recall which includes:
Semantic memory: facts and information
Episodic memory: autobiographical personal experiences
What is implicit memory?
Long term memory store which does not require recall and includes:
Procedural memory: muscle ‘memory’ like riding a bike
Perceptual priming: 2 stimuli that we associate because of similarities like ‘goat’ and ‘boat’
Classical conditioning
What is the reticular activating system?
Composed of 4 nuclei in the reticular formation located in the brain stem which project to the thalamus and cortex for wakefulness and the hypothalamus to modulate behaviour.
What are the nuclei of the reticular activating system?
Locus Coreleus
Raphe nuclei
Basal forebrain nuclei
Dorsal pontine nuclei
What is the locus coreleus nuclei?
Releases noradrenaline (NA) for arousal.
What is the raphe nuclei?
Releases serotonin for arousal and attention.
Which part of the reticular activating system is affected in dementia?
Dorsal pontine nuclei and basal forebrain nuclei. These release acetylcholine which project to cortical areas for arousal and synaptic plasticity.
What is the role of the basal forebrain nuclei?
Releases acetylcholine to project to all the cortical areas, including those involved in memory and arousal.
What is the role of the dorsal pontine nuclei?
Releases acetylcholine for synaptic plasticity and wakefulness.
Which part of the brain is involved in memory?
Medial Temporal lobe which captains the hippocampus and parahippocampal cortex.
How does the brain change with age?
Reduction in brain volume
Increase in CSF fluid.
Reduction in processing speed, attention in complex situations and problem solving.
Vocabulary and general knowledge are preserved
What is mild cognitive impairment?
Normal aging of the brain seems worsened with some mild memory impairment, which is not severe enough to affect the activities of daily living. Proportion of people with this will develop dementia.
What is dementia?
Severe deterioration in cognitive function which interferes with activities of daily living.
Before disease begins, there is anosmia (loss of sense of smell) due to olfactory cortex in temporal lobe being damaged.
Early stages of dementia involve short term memory loss and misplacing items.
As it progresses, there are issues with hygiene, aggression and not acquiring new information.
In the late stages, there is a time shift for patients who also lose verbal communication and may become more aggressive and mood disorders like depression develop.
What is the most common subtype of dementia?
Alzheimer’s disease. It is caused by extra cellular amyloid plaques and intracellular tau plaques within neurons that disrupt synaptic transmission. It typically affects the hippocampus, temporal lobes and parietal lobes and the biggest risk factor is age. It affects more women than men.
How do amyloid plaques form?
Beta-amyloid is a transmembrane component typically broken down by alpha, then beta, then gamma secretase enzymes. When beta secretase enzymes act first to break it down, then gamma secretase, it results in the formation of amyloid which accumulates on neurons extracellularly and creates an inflammatory response, leading to cell death.
How does Alzheimer’s disease progress?
It begins with short term memory loss, difficulty finding words, visuospatial disorientation and poor insight. There is agnostic (loss of recognition) and apraxia (carrying out complex tasks) anddifficulty in new environments.
What is the causes of vascular dementia?
Disruption to blood supply for the temporal lobe linked to strokes with:
Small vessel disease
Ischaemic stroke
Multi-infarct disease
There is stepwise progression, where the disease seems to suddenly gets worse.
What are the risk factors for vascular dementia?
Risk factors include smoking, hypertension, atrial fibrillation. Family history of diabetes and high cholesterol is also a risk.
What is multi-infarct disease?
Multiple strokes which reduces blood supply to the brain and result in damaged brain tissue.
What is small vessel disease?
Small penetrating vessels of the brain are damaged which impacts blood supply to the brain.
What is Lewy-Body dementia?
Caused by alpha-synuclein deposits in the brain due to brain tissue decay which can affect the substantia nigra for dopamine neurons which results in Parkinsonism. It affects many regions of the brain, ranging from the midbrain, temporal lobe, parietal lobe and cingulate gyrus.
There is fluctuating cognition, hallucinations and REM sleep disorders. During REM sleep, they may move and act out. It also involves intolerance to antipsychotic drugs.
What is the epidemiology of Lewy-Body dementia?
Typically affects older people, slightly more common in men.
What is frontal temporal dementia?
Atrophy of the frontal and temporal lobes with subtypes including:
->Behavioural varriant
->Semantic dementia
->Primary progressive aphasia
->Progressive non-fluent aphasia.
