Dementia: Definition and Types

Dementia: Definition and Types

• Dementia is a syndrome caused by brain disease, usually chronic or progressive.
• It affects multiple higher cortical functions: memory, thinking, orientation, comprehension, calculation, learning, language, and judgment.
• Consciousness remains unaffected.
• Cognitive impairment is often accompanied by deterioration in emotional control, social behavior, or motivation (WHO 1992, ICD-10).
• Many subtypes exist (70+, 100+, 200+ reported in different studies).
• Different types of memory are impacted: perceptual representation, working memory, semantic memory, episodic memory, and procedural memory.
• The "Big Four" dementia types are: Alzheimer's Disease (AD), Vascular Dementia (VaD), Dementia with Lewy Bodies (DLB), and Frontotemporal Dementia (FTD).
• Diagnostic criteria vary depending on the type of dementia, with preferred criteria differing from those used in ICD and DSM systems.

Dementia Prevalence and Statistics

• Prevalence rates increase significantly with age.
• Rates are: 1 in 1000 (40-65 years), 1 in 50 (65-70 years), 1 in 20 (70-80 years), and 1 in 5 (80+ years).
• A 2022 study showed a national diagnostic rate of 62% versus a benchmark rate of 66.7%.
• Dementia UK (2007) reported the following percentages for dementia types: DAT (62%), VaD (17%), DLB (4%), FTD (10-15%), and others (2-5%).

Alzheimer's Disease (AD)

• Characterized by dementia, gradual progression, intact consciousness, onset after age 40, and absence of other causes (NINCDS/ADRDA criteria).
• Cognitive decline progresses over time.

Vascular Dementia (VaD)

• Involves dementia, cerebrovascular disease, focal stroke signs, impairment of memory and at least one other cognitive domain, and evidence of relevant cerebrovascular disease (NINDS-AIREN criteria).
• Onset often within three months of a stroke, or may present with abrupt deterioration or fluctuating, stepwise progression.

Dementia with Lewy Bodies (DLB)

• Features progressive cognitive decline impacting daily functioning.
• Requires two of the following: fluctuating cognition, recurrent visual hallucinations, spontaneous Parkinsonism motor features.
• Supportive features include: falls, syncope, neuroleptic sensitivity, paranoid delusions, and hallucinations in other modalities (McKeith et al., 1996).

Frontotemporal Dementia (FTD)

• Characterized by insidious onset, gradual progression, early decline in social conduct, impairment in self-regulation, emotional blunting, and early loss of insight (Lund-Manchester criteria).

Dementia Progression and Outcomes

• Progression stages include mild, moderate, and severe, with a typical lifespan of 4-8 years (though it can be up to 20).
• Death often results from pneumonia or other comorbidities.

Dementia: Causes and Models

• Causes include biological factors (chromosomes, altered brain pathology), psychosocial factors (malignant social psychology), and environmental factors (lifestyle, physical environment).
• Kitwood's (1997) model emphasizes psychological needs: comfort, occupation, attachment, identity, and inclusion.
• "Malignant social psychology" describes harmful behaviors and attitudes that negatively impact people with dementia.

Therapeutic Implications

• Focus on prevention of onset, slowing progression, and treating symptoms to manage decline. Prevention is emphasized.