Clinical - Dementia
Video 1 - Alzheimer's Disease
Learning Objectives
Describe the main clinical symptoms of Alzheimer’s disease
Understand the biomarkers available for the diagnosis of Alzheimer’s disease
Understand the treatments both current and emerging for Alzheimer’s disease.
Approach to Diagnosis and Clinical Assessment
Diagnosing and managing Alzheimer’s disease (AD) is a multifactorial process that combines clinical observation with objective testing and biomarker analysis.
Multifactorial Assessment: The diagnostic approach integrates several key components:
Detailed History: Gather information on cognitive and behavioral changes from both the patient and a reliable carer/informant.
Clinical Examination: A physical and neurological exam to rule out other causes of cognitive decline.
Brain Imaging: Structural (MRI) and functional (PET) scans to look for atrophy patterns and pathology.
Biomarkers: Analysis of specific biological markers via PET imaging or cerebrospinal fluid (CSF) analysis.
Functional Assessment: Assessing how cognitive changes affect daily life is crucial.
Cambridge Behavioural Inventory (CBI):
Typically completed by carers before clinic visits.
Evaluates subtle changes in memory, attention, orientation, and daily function (e.g., apathy, self-care).
Provides vital context for tracking cognitive and behavioral decline over time.
Cognitive Testing: Formal testing helps quantify cognitive deficits:
Mini-Mental State Examination (MMSE):
Historically the standard screening tool, but considered a crude measure today.
Provides only a general snapshot of cognition.
Addenbrooke’s Cognitive Examination (ACE):
Often the preferred tool for detailed assessment.
Tests specific cognitive domains: attention, verbal fluency, memory, visuospatial function, and language.
Allows for a more accurate and nuanced characterization of the patient's specific deficits.
Diagnostic Criteria - A Disease Continuum: Current diagnostic frameworks (e.g., the 2011 criteria) view Alzheimer's as a biological continuum defined by stages of pathology, not just clinical symptoms:
Preclinical AD:
No outward clinical symptoms are present.
Biomarker evidence exists (e.g., abnormal A-beta detected via PET scan or altered A-beta/tau ratio in CSF).
Mild Cognitive Impairment (MCI) due to AD:
Mild but measurable memory or cognitive changes are present.
These changes do not yet interfere with Activities of Daily Living (ADLs).
Dementia due to AD:
Deficits are present in two or more domains of cognition/behavior.
The decline is severe enough to interfere with daily life and independence.
Note: New diagnostic criteria are currently under review but continue to emphasize this biomarker-based, stage-specific model.
Clinical Presentations of Alzheimer’s Disease (AD)
Alzheimer's disease most commonly presents as a memory disorder (amnestic type) but can also manifest in atypical ways depending on which part of the brain is initially affected by the pathology.
Typical (Amnestic) Presentation: This is the classical and most common pattern of AD, characterized by predominant episodic memory impairment.
Early Features:
Memory Loss: Loss of short-term memory (e.g., forgetting recent conversations or events) is the first sign.
Long-term memory usually remains preserved early on.
Language and Orientation: Anomia (difficulty naming objects), word-finding difficulty, and problems with orientation (getting lost, confusion about dates/times).
Executive Function: Subtle executive dysfunction (e.g., difficulty with problem-solving or multitasking) and loss of confidence.
Other Skills: Decline in basic arithmetic and spelling skills.
Observations:
Preserved Social Façade: Patients often maintain a socially appropriate and articulate demeanor in the early stages, despite significant underlying cognitive impairment.
Physical Exam:
Usually normal in early stages
Physical signs like myoclonus (muscle twitching) may appear in later stages.
Atypical (Non-Amnestic) Presentations: In these less common variants, pathology is concentrated in different brain regions, leading to different initial symptoms.
Posterior Cortical Atrophy (PCA):
Pathology Location: Concentrated primarily in the parietal and occipital lobes (areas responsible for vision and spatial processing).
Onset: Typically occurs at a younger age than typical AD.
Clinical Features:
Visual Deficits: Visual processing deficits (e.g., difficulty recognizing objects, reading, or judging depth perception).
Visuospatial Disorientation: Getting lost easily in familiar places.
Apraxia: Impaired learned motor sequences (difficulty performing purposeful movements).
Acalculia: Difficulty with basic calculation.
Memory: Memory is often preserved initially but declines as the disease progresses and spreads.
Logopenic Variant Primary Progressive Aphasia (lvPPA):
Pathology Location: Centered on the left temporoparietal regions (language centers).
Core Features (Language Deficits):
Word-finding pauses and hesitant, halting speech.
Anomia (naming difficulty).
Reduced digit span (impaired short-term verbal memory).
Difficulty repeating phrases or sentences, though they can often repeat single words.
Memory & Cognitive Function: Memory and other cognitive functions are generally preserved at first but decline as the disease becomes global.
Diagnosis: Biomarkers and Differentials
Typical Clinical Presentation: The classic symptom that prompts clinical investigation is short-term (episodic) memory impairment:
Patients typically forget recent events or conversations.
Long-term memory usually remains intact in the early stages of the disease.
Biomarkers in Diagnosis: Biomarkers provide objective evidence of the underlying disease process (amyloid accumulation and tau spread). These changes often occur presymptomatically and are measurable via CSF analysis or PET imaging.
Cerebrospinal Fluid (CSF) Biomarkers:
Biomarkers: CSF is obtained via a lumbar puncture and analyzed for key proteins:
A-beta 42: Levels are decreased in AD because the peptide is deposited in brain plaques, reducing the amount circulating in the CSF.
Tau (Total and Phosphorylated): Levels are increased in AD, reflecting axonal damage, neuronal injury, and neurodegeneration.
Interpretation: A typical Alzheimer’s disease CSF pattern decreased A-beta 42 and increased Tau provides high diagnostic sensitivity and specificity (85–90%).
Neuroimaging: Imaging techniques visualize structural damage and protein deposition patterns:
MRI Brain (Structural Imaging): Reveals patterns of atrophy (brain shrinkage) consistent with the disease subtype.
Typical AD: Prominent hippocampal and temporal lobe atrophy.
Posterior Cortical Atrophy Variant: Distinct parietal and occipital atrophy, corresponding to visual and visuospatial deficits.
FDG-PET Scan (Functional Imaging): Measures glucose metabolism (a proxy for brain activity).
Healthy Brain: In a healthy brain, high activity is seen in the posterior cortex.
PCA Variant: In AD, affected regions show reduced activity (hypometabolism), particularly in the posterior parietal and occipital regions.
Amyloid PET (Molecular Imaging): Directly detects A-beta deposition in the brain.
In AD, scans show extensive cortical amyloid uptake, confirming the amyloid burden.
This is a powerful research tool and increasingly used clinically.
Differential Diagnoses: When evaluating memory complaints, it is critical to exclude other potential causes of cognitive decline, as some may be treatable or present differently:
Psychiatric Causes: Depression and anxiety can mimic early AD symptoms, a condition sometimes referred to as "pseudodementia."
Other Neurodegenerative Diseases: Vascular cognitive impairment, Lewy body dementia, and frontotemporal dementia.
Seizure-Related: Transient epileptic amnesia.
Autoimmune/Neoplastic: Encephalitis (autoimmune or paraneoplastic) or brain tumors.
Metabolic/Nutritional: Thyroid dysfunction, vitamin B12 deficiency, liver disease, or renal disease.
Infectious: HIV, neurosyphilis, prion disease.
Toxic: Alcohol-related damage, such as Korsakoff’s psychosis due to thiamine deficiency.
Treatment of Alzheimer’s Disease
Overview: There is currently no cure for Alzheimer’s disease (AD). Available treatments focus on managing symptoms, maintaining daily function, improving quality of life, and, with newer therapies, potentially modifying the disease process itself.
Current PBS Approved Therapies: In Australia, two main classes of symptomatic drugs are funded by the Pharmaceutical Benefits Scheme (PBS).
Cholinesterase Inhibitors: This class of drugs aims to boost neurotransmission in the brain.
Examples:
Donepezil (brand name Aricept) is the main PBS-funded option.
Rivastigmine and galantamine are also available but less common.
Mechanism of Action: These drugs inhibit acetylcholinesterase, the enzyme responsible for breaking down acetylcholine in the synaptic cleft. This action increases acetylcholine levels, enhancing neuronal communication and improving cognitive function.
Clinical Use: Used for patients with mild, moderate, and severe AD. Moderate-quality evidence supports small but significant improvements in cognitive function, activities of daily living (ADLs), and global functioning.
Side Effects and Precautions:
Common: Gastrointestinal upset (nausea, vomiting, diarrhea).
Cardiac: May prolong the PR interval and cause heart block. Use caution in patients with bradycardia or existing cardiac disease.
Before starting treatment, an ECG should be performed to screen for heart block or conduction abnormalities.
Other: Vivid dreams or insomnia.
NMDA Receptor Antagonist: This medication works differently to protect neurons from damage caused by overactivity of neurotransmitters.
Example: Memantine.
Mechanism of Action: Blocks NMDA glutamate receptors. By preventing excessive calcium influx into neurons, it reduces excitotoxic damage and helps stabilize neuronal activity and cognition.
Clinical Use: Evidence supports modest improvements in cognition and ADLs and may slow functional decline in moderate to severe AD.
Can be used alone or in combination with Donepezil.
Emerging Therapies: Monoclonal Antibodies (Anti-Amyloid Agents): These therapies represent the first true disease-modifying treatments by targeting the underlying pathology of AD. They are currently approved in the USA but not yet by the TGA in Australia.
Overview: These antibodies target beta-amyloid A-beta deposition to reduce or remove amyloid plaques from the brain, aiming to slow the disease process rather than just treating symptoms.
Key Agents and Evidence Summary:
Aducanumab: Binds aggregated A-beta to enhance clearance. Early FDA approval was controversial due to mixed trial results.
Lecanemab (Leqembi): Clears both soluble and insoluble A-beta. Showed moderate benefit, slowing cognitive decline by approximately 4–7 months in early-stage patients.
Donanemab: Promotes plaque removal. Early evidence also suggests cognitive benefits.
Effect Size: The observed benefit is modest, typically a ~ 27–30% reduction in the rate of cognitive decline.
The primary benefit is slowing, not reversing, disease progression.
Major Risks - ARIA: A significant concern is Amyloid-Related Imaging Abnormalities (ARIA):
ARIA-E: Cerebral edema (brain swelling).
ARIA-H: Hemorrhage or microbleeds in the brain.
Risk Factors:
Patients who are APOE4 homozygotes have a significantly increased risk of ARIA.
Use of anticoagulation medication or the presence of cerebral amyloid angiopathy are contraindications due to bleeding risks.
Video 2 - Dementia with Lewy Bodies
Learning Objectives
Describe the clinical feature of Dementia with Lewy bodies
Describe the treatment of Dementia with Lewy bodies
General Overview
Overview:
Dementia with Lewy Bodies (DLB) is the second most common cause of late-onset dementia after Alzheimer’s disease.
It tends to be more functionally disabling than AD
It is characterized by abnormal intracellular inclusions called Lewy bodies, composed primarily of the protein alpha-synuclein
DLB vs. Parkinson’s Disease Dementia (PDD): DLB and PDD share similar symptoms (cognitive impairment and parkinsonism), but the timing of symptoms distinguishes them:
DLB: Cognitive symptoms occur at least one year before motor symptoms (parkinsonism).
PDD: Motor symptoms (tremor, rigidity) precede dementia by at least one year.
Core Clinical Features: DLB is defined by a characteristic set of core clinical features:
Fluctuating Cognition and Attention: Patients experience significant variations in attention and alertness, with alternating periods of lucidity and confusion.
This can sometimes resemble delirium and involves episodes of drowsiness and inattention.
Recurrent Visual Hallucinations: These hallucinations are typically vivid, well-formed, and often occur daily.
Patients commonly report seeing people, animals, or shadowy figures, often at the periphery of their vision.
Spontaneous Parkinsonism: The presence of motor symptoms typical of Parkinson's disease:
Bradykinesia (slowness of movement).
Rigidity.
Tremor may occur but is less common than in idiopathic Parkinson’s disease.
Postural instability and a shuffling gait are frequent.
REM Sleep Behaviour Disorder (RBD): A strong indicator where individuals physically "act out" their dreams during REM sleep (e.g., falling out of bed, punching, kicking, or injuring a bed partner).
Autonomic Dysfunction: Problems with involuntary bodily functions are seen in up to 90% of patients and are a useful differentiating feature from AD:
Orthostatic hypotension (a drop in blood pressure upon standing).
Urinary frequency and nocturia (frequent urination at night).
Neuropsychiatric Symptoms and Drug Sensitivity: Depression, anxiety, and a proneness to delirium are common.
Physical Examination: Findings on physical examination are consistent with parkinsonism:
Bradykinesia, rigidity, and sometimes a resting tremor.
Slow, shuffling gait, poor postural reflexes, and reduced arm swing.
Facial hypomimia (reduced facial expression).
Treatment of Dementia with Lewy Bodies (DLB)
Overview:
Currently, there is no approved disease-modifying therapy specifically for DLB.
Management focuses purely on symptomatic treatment, cautiously adapting therapies used for both Alzheimer's disease and Parkinson's disease.
General Approach:
Management involves addressing cognitive symptoms, motor symptoms, and behavioral issues.
Extreme caution is required with certain classes of medications, particularly antipsychotics.
Pharmacological Management:
Acetylcholinesterase Inhibitors (AChEIs): These drugs are often the first-line treatment for cognitive and behavioral symptoms in DLB.
Examples: Donepezil, Rivastigmine.
Mechanism: Inhibiting the breakdown of acetylcholine to increase its levels in the synaptic cleft.
Benefits: These drugs improve attention, reaction time, and cognition. They also help reduce the characteristic fluctuations in alertness and manage neuropsychiatric symptoms like hallucinations and confusion.
Dopaminergic Therapy: These medications are used to address the parkinsonian motor symptoms.
Example: Levodopa.
Use and Caution: Levodopa can improve rigidity and bradykinesia.
However, it must be used cautiously because it can exacerbate hallucinations or confusion.
Therapy should be trialed only under careful monitoring.
Antipsychotic Use (Extreme Caution Required): DLB patients have a high sensitivity to antipsychotic medications, which is a key clinical feature.
Risk: Typical and many atypical antipsychotics (e.g., haloperidol, risperidone, olanzapine) can severely worsen parkinsonism, cause profound rigidity, or lead to dangerous neuroleptic malignant-like reactions.
Safest Option: If antipsychotic therapy is absolutely unavoidable, low-dose quetiapine is considered the safest option.
Anesthesia: General anesthetics can precipitate prolonged confusion or severe cognitive worsening in DLB patients and should be used with extreme caution during surgical procedures.
Video 3 - Frontotemporal Dementia
Learning Objectives
Describe the main clinical symptoms of the different forms of frontotemporal dementia
Describe the clinical cross over between frontotemporal dementia and Parkinsonism
General Overview
Frontotemporal Dementia (FTD):
Frontotemporal Dementia (FTD) is notable as the most common cause of young-onset dementia, typically occurring in patients under 65 years old.
The disease primarily targets the frontal and temporal lobes, resulting in distinct changes in personality, behavior, and language rather than the early memory loss typical of Alzheimer's disease.
Major Clinical Subtypes: FTD is classified into three major clinical presentations based on the most affected region:
Behavioural Variant FTD (bvFTD): Characterized by profound personality changes.
Semantic Dementia (SD): Characterized by the loss of conceptual knowledge and word meaning.
Progressive Non-Fluent Aphasia (PNFA): Characterized by difficulty producing speech.
Key Clinical Features of FTD (General): While specific symptoms vary by subtype, general features of FTD include:
Behavioural and Personality Changes: Common symptoms include apathy, disinhibition (socially inappropriate behavior), loss of empathy, and compulsive or ritualistic behaviors.
Loss of Emotional Processing: Reduced empathy or a lack of appropriate emotional response to others' feelings.
Eating Changes: Patients often develop a strong preference for sweet foods, overeat, or develop rigid, unchanging food choices.
Relative Memory Sparing: A crucial differentiating factor from Alzheimer's disease is that memory is often relatively preserved in the early stages of FTD.
The behavioral and emotional changes precede memory loss.
Clinical Subtypes of Frontotemporal Dementia (FTD)
FTD presents in specific clinical subtypes depending on which region of the frontal or temporal lobes is most affected first.
Behavioural Variant FTD (bvFTD): This is the most common FTD subtype, characterized by profound personality and behavioral changes.
Core Features:
Significant personality change, emotional blunting, impulsivity, and socially inappropriate actions.
Apathy or a complete lack of motivation.
Poor insight into their own condition and reduced empathy toward others.
Other Features:
Loss of judgment, repetitive behaviors, and changes in personal hygiene or habits.
May develop a strong sweet food preference or hyperphagia (excessive eating).
Cognition:
Memory is relatively preserved early on.
Executive dysfunction (problems with planning, organization, and reasoning) predominates the cognitive profile.
Imaging: MRI typically shows atrophy (shrinkage) in the frontal and anterior temporal lobes, often on both sides of the brain.
Semantic Dementia (SD): This subtype, also termed the semantic variant Primary Progressive Aphasia (svPPA), is a language variant of FTD.
Clinical Features:
The primary deficit is a loss of knowledge about the meaning of words and objects. Patients may use a familiar object but be unable to name it or explain what it is.
Speech is fluent and grammatically correct but lacks substance or content ("empty speech"), often relying on non-specific words like "thing" or "stuff."
Insight is often preserved early in the disease, but comprehension loss progresses. Rigid thinking and routines are common.
Imaging and Asymmetry:
Left Anterior Temporal Lobe Atrophy: The typical presentation, causing the language-predominant symptoms.
Right Anterior Temporal Lobe Atrophy: Leads to a more behavioral presentation, including prosopagnosia (difficulty recognizing faces) and emotional disinhibition. Some loss of general word/object meaning also occurs as the disease progresses.
Progressive Non-Fluent Aphasia (PNFA): Also known as the non-fluent/agrammatic variant Primary Progressive Aphasia (nfvPPA), this subtype affects speech production.
Clinical Features:
Speech is effortful, halting, and non-fluent.
Agrammatism → Difficulty with sentence structure and grammar. Writing or emails often contain grammatical errors or lack logical flow.
Speech production errors are common, including hesitations and phonemic errors.
Comprehension of individual words and object knowledge remains preserved (unlike semantic dementia).
Reading and writing are often affected due to the underlying grammatical difficulties.
Imaging: MRI shows atrophy concentrated around the left perisylvian fissure, which corresponds to the language production area (Broca’s region).