12.3 Neurodegenerative Disorders

Neurodegenerative disorders like Alzheimer's, Parkinson's, and Huntington's disease progressively damage the brain. These conditions share common themes of protein misfolding, neuronal loss, and gradual onset of symptoms that worsen over time, affecting memory, movement, and cognition.

Understanding the pathophysiology, clinical manifestations, and progression of these disorders is crucial for nurses. This knowledge informs patient care, from recognizing early signs to managing symptoms and supporting patients and families through the challenging journey of neurodegenerative disease.

Pathophysiology and Clinical Manifestations

Neurodegenerative disorders: pathophysiology and progression

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• Alzheimer's disease
  • Pathophysiology
    • Accumulation of beta-amyloid plaques outside neurons disrupts cell function
    • Neurofibrillary tangles of tau protein inside neurons impair nutrient transport
    • Progressive neuronal loss leads to brain atrophy particularly in hippocampus and cortex
  • Clinical manifestations
    • Memory loss especially short-term memory affects daily activities (forgetting recent conversations)
    • Difficulty with problem-solving and planning impairs decision-making (managing finances)
    • Language impairment causes trouble finding words or following conversations
    • Disorientation to time and place results in wandering or getting lost
  • Progression
    • Gradual onset often mistaken for normal aging
    • Steady decline over 8-10 years with increasing dependence on caregivers
• Parkinson's disease
  • Pathophysiology
    • Loss of dopaminergic neurons in substantia nigra reduces dopamine production
    • Presence of Lewy bodies (protein aggregates) in surviving neurons
    • Disruption of basal ganglia function affects movement control
  • Clinical manifestations
    • Tremor at rest typically starts in one hand (pill-rolling tremor)
    • Bradykinesia slows movement initiation and execution
    • Rigidity causes stiffness and resistance to passive movement
    • Postural instability increases fall risk
  • Progression
    • Gradual onset often begins with subtle unilateral symptoms
    • Slow progression over 10-20 years with increasing disability
• Huntington's disease
  • Pathophysiology
    • CAG trinucleotide repeat expansion in huntingtin gene causes protein misfolding
    • Accumulation of mutant huntingtin protein forms toxic aggregates
    • Selective neuronal loss in striatum and cortex affects motor and cognitive functions
  • Clinical manifestations
    • Chorea causes involuntary dance-like movements
    • Cognitive decline affects memory executive function and attention
    • Psychiatric symptoms include depression irritability and impulsivity
  • Progression
    • Adult-onset typically 30-50 years old with earlier onset correlating with longer CAG repeats
    • Steady decline over 15-20 years leading to complete dependence and premature death

Risk factors for neurodegenerative disorders

• Genetic risk factors
  • Alzheimer's disease
    • APOE ε4 allele increases risk and lowers age of onset
    • Mutations in APP PSEN1 and PSEN2 genes cause early-onset familial AD
  • Parkinson's disease
    • Mutations in LRRK2 PARK7 and SNCA genes increase susceptibility
  • Huntington's disease
    • Autosomal dominant inheritance of HTT gene mutation guarantees disease development
• Environmental risk factors
  • Advanced age primary risk factor for most neurodegenerative disorders
  • Traumatic brain injury increases risk of cognitive decline and Parkinson's disease
  • Exposure to toxins linked to increased risk (pesticides heavy metals)
  • Chronic inflammation contributes to neuronal damage and disease progression
  • Vascular risk factors increase likelihood of cognitive decline (hypertension diabetes obesity)

Management of neurodegenerative disorders

• Pharmacological interventions
  • Alzheimer's disease
    • Cholinesterase inhibitors boost acetylcholine levels (donepezil rivastigmine galantamine)
    • NMDA receptor antagonist regulates glutamate activity (memantine)
  • Parkinson's disease
    • Levodopa/carbidopa replenishes dopamine in the brain
    • Dopamine agonists stimulate dopamine receptors (pramipexole ropinirole)
    • MAO-B inhibitors prevent dopamine breakdown (selegiline rasagiline)
  • Huntington's disease
    • Tetrabenazine reduces chorea by depleting monoamines
    • Antipsychotics manage psychiatric symptoms and may help with chorea
• Non-pharmacological interventions
  • Cognitive stimulation therapy maintains mental function (puzzles memory games)
  • Physical exercise improves motor function and mood (tailored to individual abilities)
  • Occupational therapy enhances daily living skills and independence
  • Speech and language therapy addresses communication and swallowing difficulties
  • Dietary modifications support overall health (Mediterranean diet for AD)
  • Environmental adaptations improve safety and function (removing trip hazards)

Psychosocial impact of neurodegenerative disorders

• Psychosocial impact on patients
  • Loss of independence affects self-esteem and quality of life
  • Depression and anxiety common comorbidities requiring management
  • Social isolation results from communication difficulties and stigma
  • Changes in self-image and identity as roles and abilities change
• Impact on families
  • Caregiver burden and stress increases risk of physical and mental health problems
  • Financial strain from medical costs and potential loss of income
  • Changes in family dynamics as roles shift and responsibilities increase
  • Anticipatory grief process begins as disease progresses
• Nurse's role in providing support
  • Patient and family education about disease process prognosis and management
  • Assistance with advance care planning to ensure patient wishes are respected
  • Referrals to support groups and community resources for additional help
  • Monitoring for caregiver burnout and providing interventions
  • Coordination of multidisciplinary care for comprehensive management
  • Advocacy for patient and family needs within healthcare system
• Resources for patients and families
  • Alzheimer's Association offers education support and research updates
  • Parkinson's Foundation provides resources for patients and caregivers
  • Huntington's Disease Society of America offers support and advocacy
  • Local support groups provide peer support and shared experiences
  • Respite care services offer temporary relief for caregivers
  • Home health and hospice agencies provide in-home care and end-of-life support