Neurocognitive Disorders Overview

Overview of Neurocognitive Disorders 認知障礙症

  • Definition: A category of mental disorders affecting cognitive functions such as learning, memory, attention, language, motor behavior, and consciousness.

  • Development: Most neurocognitive disorders develop later in life.

  • Causes:

    • Aging

    • Medical conditions

    • Abnormal brain structures

    • Drug use

    • Environmental factors

Types of Neurocognitive Disorders

  • Delirium精神錯亂: Temporary confusion and disorientation.

  • Major and Mild Neurocognitive Disorder: Broad cognitive deterioration affecting multiple domains.

DSM Perspectives Shift

  • The field has transitioned from viewing these disorders strictly as "organic" (brain damage) to understanding them as "cognitive" disorders that significantly affect behavior and personality.

Delirium

  • Key Features:

    • Impaired consciousness (awareness and attention)

    • Impaired cognition (including memory deficits, disorientation, language issues)

    • Rapid development over hours or days.

    • Symptoms include confusion, disorientation, inattentiveness, and memory/language deficits.

  • Statistics:

    • Affects up to 20% of adults in acute care settings (e.g., emergency rooms).

    • More prevalent among older adults and those undergoing medical procedures.

    • Often, recovery occurs within several weeks.

Major and Mild Neurocognitive Disorders

  • DSM-5 Criteria for Major Neurocognitive Disorder:

    • Significant cognitive decline in complex attention, executive function, learning and memory, language, perceptual-motor, or social cognition.

    • Substantiated by clinical assessment, affecting independence.

Symptoms and Progression

  • Initial Symptoms:

    • Memory and visuospatial skills impairments.

    • Agnosia: Inability to recognize and name objects (most common symptom).

    • Other symptoms include delusions, apathy, depression, agitation, and aggression.

  • Later Stages:

    • Further deterioration of cognitive function.

    • Total support required for daily activities.

    • Increased risk for early death due to inactivity and other illnesses.

Prevalence and Statistics

  • Major Neurocognitive Disorders:

    • New cases identified every 7 seconds.

    • 5% prevalence in adults aged 65+, rising to 20-40% in those over 85.

    • Mild neurocognitive disorder prevalence is greater (10% in adults over 70).

    • Nature of Dementia: Gradual deterioration in brain function, judgment, memory, and language.

Etiology

  • Caused by various diseases including Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, and other medical conditions like traumatic brain injuries, HIV infection, vascular injuries, etc.

Alzheimer’s Disease 阿茲海默 （老人癡呆）

  • Prevalence: Accounts for nearly half of neurocognitive disorders.

  • Clinical Features:

    • Gradual and steady onset of memory, orientation, judgment, and reasoning deficits.

    • Symptoms worsen with time, leading to isolation and further cognitive decline.

    • “Sundowner syndrome”: Symptoms increase in severity later in the day.

Diagnosis Criteria (DSM-5)

  • Meets criteria for major or mild neurocognitive disorder.

  • Gradual onset and progressive impairment in cognitive domains.

  • Evidence of causative genetic mutation for Alzheimer's (if applicable).

  • Exclusion of other conditions that might explain cognitive issues.

Cognitive Deficits in Alzheimer’s

  • Common Deficits:

    • Aphasia: Language difficulties.

    • Apraxia: Impaired motor functioning.

    • Agnosia: Inability to recognize objects.

    • Impacts planning, organizing, and abstract thinking.

Statistics and Studies

  • Survival Rates: Average post-diagnosis survival is about 4 to 8 years, but some live more than 20 years.

  • Prevalence: 5 million Americans affected, varies by education levels.

  • More common in women; a higher level of education may delay onset but does not prevent the disease.

The Cognitive Reserve Hypothesis

  • Suggests that greater synaptic development through education or mental activity provides a buffer against dementia symptoms.

Biological Aspects of Alzheimer’s Disease

  • Brain Features:

    • Neurofibrillary tangles and amyloid plaques identified as common characteristics.

    • Genetic contributions from deterministic and susceptibility genes.

Gene-Environment Interaction

  • Stressful environments increase cognitive decline risk, especially with apolipoprotein E (apo E4) gene.

Psychosocial Factors

  • Although psychosocial factors do not directly cause dementia, they may affect its onset and progression:

    • Lifestyle choices (diet, exercise, drug use) and cultural factors (ethnic and class differences).

    • Educational attainment and social support are influential.

Treatment Options

Medical Treatments

  • No cure; treatments primarily aim to slow progression:

    • Cholinesterase-inhibitors: Used to target cognitive deficits.

    • Other exploratory treatments include Ginkgo biloba for memory improvement (mixed findings).

Psychological Treatments

  • Aims to enhance quality of life, teach compensatory skills, and provide support for caregivers.

    • Memory-enhancing devices (e.g., “memory wallets”).

    • Support systems for caregivers to manage stress and challenges.

Prevention Strategies

  • Focus on reducing risk for older adults through:

    • Anti-inflammatory medications, blood pressure control, active social engagement, and safe behaviors to avoid head trauma.

    • Avoiding exposure to neurotoxins.