Dementia

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Definition

Loss of intellectual abilities previously attained (memory, judgment, abstract thought, and other higher cortical functions) severe enough to interfere with social and/or occupational functioning.

Clinical features

Memory deficit

Cardinal feature;

DSM-IV definition requires impairment in at least one other domain (language, perception, visuospatial function, calculation, judgment, abstraction, problem-solving skills).

Numbers

Affects 3–11% of community-dwelling adults > 65 yrs of age,

Greater presence among institutionalized residents.

Risk factors

Advanced age

Family history of dementia

Apolipoprotein E-4 allele

Brain biopsy for dementia.

Rarely needed

Clinical criteria are usually sufficient for the diagnosis of most dementias.

Biopsy indication

Chronic progressive cerebral disorder with an unusual clinical course where all other possible diagnostic methods have been exhausted and have failed to provide adequate diagnostic certainty.
Eg

Pick disease
Binswanger disease
Niemann-Pick disease
Lewy body disease

Biopsy may show

CJD

The high incidence of CJD among patients selected for biopsy under these criteria necessitates appropriate precautions;

Low grade astrocytoma
AD

Specimen

Be large enough (usually 1cm³)
Be taken from an affected area
Include gray and white matter, pia and dura
Be handled carefully to minimize artifact (electrocautery should not be used on the specimen side of the incision)

Diagnostic yield

20% (6% were only suggestive of a diagnosis, 66% were abnormal but nonspecific, 8% were normal).
The yield was highest in those with focal MRI abnormalities.

Perform MRI and if not abnormalities use SPECT or PET scan

Out of 10 pt with biopsies, the biopsy result led to a meaningful therapeutic intervention in only 4.

Differential diagnosis

Delirium

AKA acute confusional state.
Distinct from dementia;

Patients with dementia are at increased risk of developing delirium.

A primary disorder of attention that subsequently affects all other aspects of cognition.
Often represents life-threatening illness

e.g. hypoxia, sepsis, uremic encephalopathy, electrolyte abnormality, drug intoxication, MI.

50% of patients die within 2 yrs of this diagnosis.
Delirium vs. dementia (critical distinction)

Unlike dementia, delirium has acute onset, motor signs (tremor, myoclonus, asterixis), slurred speech, altered consciousness (hyperalert/agitated or lethargic, or fluctuations), hallucinations may be florid.
EEG shows pronounced diffuse slowing.

Summary

Disease	Presentation	Diagnostics	Other	Treatment
Wernicke’s encephalopathy	- Acute dementia - Horizontal gaze palsy - Ataxia	MRI FLAIR: signal increased in - Mammillary bodies - Dorsomedial thalamus - Tectal plate - Periaqueductal area near 3rd ventricle	Deficiency of thiamine (vitamin B1): - Chronic alcoholism - Malnutrition - Chemotherapy	100-mg thiamine (B1) IV + daily oral administration
Korsakoff’s syndrome	- Chronic dementia - Amnesia - Confabulation	ㅤ	Deficiency of thiamine (vitamin B1): - Chronic alcoholism - Malnutrition - Chemotherapy	100-mg thiamine (B1) IV + daily oral administration
Creutzfeldt–Jacob disease (CJD)	- Dementia - Myoclonus - Ataxia, clumsiness, dysarthria, diplopia, vision changes, cortical blindness - Visual agnosia, color perception changes	1. EEG: periodic spikes at 1–2 Hz frequency (PSWC) 2. Lumbar puncture: normal/increased protein; 14–3–3 protein has highest sensitivity and specificity for CJD 3. MRI (FLAIR and DWI): abnormalities in cerebral cortex/striatum/thalamus	ㅤ	Treatment: NONE Prognosis: death in <1 year
Alzheimer’s disease	Most common cause of dementia	MRI: temporal and parietal atrophy	Neurofibrillary tangle (abnormally phosphorylated tau protein; may also be present in other disease) + senile plaques (β-amyloid)	1. Cholinesterase inhibitors/memantine (for cognitive symptoms) 2. Selective serotonin reuptake inhibitors (for depression) 3. Atypical antipsychotics (for agitation). Use of this medication may increase risk of mortality, cerebrovascular events, cardiovascular and metabolic complications, infections, falls. 4. Do not use benzodiazepines Prognosis: death in 5 years: 70%
Pick’s disease	- Dementia - Changes in behavior - Progressive nonfluent aphasia	MRI: frontal + temporal atrophy	Tau proteins in neurons (silver staining: Pick’s bodies)	There is no therapy
Lewy body disease	- Second most common cause of dementia - Sleep disturbance - May include Parkinsonian symptoms	MRI: temporal + parietal + occipital atrophy	Lewy bodies: alpha-synuclein protein in neurons	1. Cholinesterase inhibitors (for cognitive symptoms) 2. Levodopa (in case of significant Parkinsonian symptoms) 3. Melatonin/clonazepam (for sleep disorders) 4. Use atypical antipsychotics if absolutely necessary, avoid the typical ones
Transient global amnesia (TGA)	- Complete, reversible anterograde and retrograde memory loss (≤24h) - Persistent memory loss during attack (bewilderment, repeating questions) - Retained identity and complex task performance - Middle/older aged men - Emotional/other stressors (physical/sexual exertion) - Not associated with increased stroke risk	Clinical diagnosis	ㅤ	Supportive
Huntington’s Disease	- Dementia - Delusions - Dysarthria - Tremor - Myoclonus - Seizures - Spasticity - Argyll Robertson pupils	Clinical diagnosis	ㅤ	Supportive
Neurosyphilis (general paresis)	- Dementia, delusions, dysarthria, tremor, myoclonus, seizures, spasticity, Argyll Robertson pupils - Chronic, insidious meningoencephalitis - May delay ≤20years after initial infection - Other: meningitis, meningovascular syphilis, optic atrophy, tabes dorsalis (ataxia, urinary incontinence, lightning pains)	Serology (Syphilis), CSF, clinical assessment	May develop years after syphilitic infection	Treat underlying infection
Hypothyroidism in adults	- Headache - Dementia - Psychosis - Decreased consciousness - Macroglossia (due to mucopolysaccharides) - Proximal myopathic weakness - Delayed relaxation phase of reflexes	Thyroid function tests	ㅤ	Thyroid hormone replacement

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