Updated: 5/29/2018

Other Causes of Dementia

Review Topic
  • A 62-year-old man presents to his primary care physician due to trouble with walking and difficulty with concentrating. The patient describes his walking as if he is "stuck to the ground." On gait testing, the patient has magnetic gait and on montreal cognitive assessment (MoCA) testing, he has a deficit in executive functioning. Laboratory tests are ordered and return normal. Lumbar puncture shows a normal opening pressure and magnetic resonance imaging (MRI) of the head is shown. (Normal pressure hydrocephalus)
  • Clinical definition
    • dementia describes a gradual and progressive decline in
      • memory and other cognitive abilities (e.g., language and visuospatial function)
  • Etiology
    • dementia can be divided into
      • primary dementia
        • usually associated with neurodegenerative diseases (e.g., Alzheimer's disease)
      • secondary dementia
        • due to secondary causes (e.g., hypothyroidism)
  • Management
    • given the large array of causes of dementia
      • it is important to focus on identifying and treating reversible causes of dementia
    • laboratory tests such as
      • vitamin B12 levels
      • thyroid function tests
      • serum syphillis tests in endemic areas
    • MRI is ideally used
    • tests are ordered in order to support one's clinical suspicion
  • Examples of dementia given in section below
Vascular Dementia
  • Clinical definition
    • a heterogenous syndrome leading to dementia secondary to
      • cerebrovascular disease that range from
        • mild deficits in cognition to frank dementia
  • Epidemilogy
    • incidence
      • second most common cause of dementia after Alzheimer's disease
    • risk factors
      • elderly
      • multiple vascular risk factors (e.g., atherosclerosis, lipohyalinosis, and cerebral amyloid angiopathy)
  • Pathogenesis
    • cerebrovascular lesions impair brain function leading to
      • vascular dementia
  • Presentation
    • clinial presentation is diverse and depends on where the damage is
      • cortical features
        • executive dysfuction and abulia/apathy in lesions affecting the
          • medial frontal lobe
        • aphasia in lesions affecting the
          • left parietal lobe
        • visuospatial difficulty in lesions affecting the
          • right parietal lobe
      • subcortical features
        • focal motor signs
        • unsteadiness and unprovoked falls
        • mild memory deficit
        • abnormal executive function
  • Imaging
    • MRI may show
      • white matter lesions (leukoaraiosis)
        • this is a non-specific finding
      • cortical and/or sub-cortical infarcts
  • Diagnosis
    • certain criteria highlights clinical findings suggestive of vascular dementia, such as
      • stepwise deterioration of cognitive function
        • memory impairment is of late-onset
      • hypertension
      • stroke history
      • focal neurologic symptoms
      • fluctuating symptoms
  • Treatment
    • treat and prevent vascular risk factors
      • e.g., managing hypertension and diabetes
    • pharmacologic therapy
      • acetylcholinesterase inhibitors (e.g., donepezil)
      • N-methyl-D-aspartate (NMDA) receptor antagonists (e.g., memantine)
Normal Pressure Hydrocephalus
  • Clinical definition
    • pathologically enlarged ventricles in the setting of
      • a normal opening pressure noted on lumbar puncture
    • a potentially reversible cause of dementia
  • Pathogenesis
    • believed to be due to
      • impaired cerebral spinal fluid (CSF) absorption which can be due to
        • previous intraventricular hemorrhage
        • previous subarachnoid hemorrhage
        • previous acute or chronic meningitis
        • Paget disease involving the
          • base of the skull
      • this results in fibrotic changes of the arachnoid granulations
  • Presentation
    • the classic triad is
      • dementia
      • gait disturbances
      • urinary incontinence
  • Diagnosis
    • MRI or CT of the head, which shows
      • ventriculomegaly that is not
        • completely attributable to cerebral atrophy
    • Lumbar puncture should show
      • normal (or mildly elevated) CSF opening pressures
  • Treatment 
    • ventricular shunting
Dementia Secondary to Infection
  • HIV-associated neurocognitive disorder
    • clinical definition
      • cognitive impairement secondary to HIV infection and
        • cannot be explained by some other etiology
    • epidemiology
      • risk factors
        • lower CD4+ cell counts
    • presentation
      • in HIV-associated dementia
        • patients typically have a CD4+ cell count < 200 cells/μL
        • dementia
        • impaired executive function
        • subcortical dysfunction such as
          • impairments with attention and concentration
          • depressive symptoms
    • treatment
      • antiretroviral therapy (ART)
  • Neurosyphilis
Dementia Secondary to Metabolic Causes
  • Thiamine deficiency (Wernicke-Korsakoff encephalopathy)
  • Vitamin B12 deficiency
  • Hypothyroidism
  • Alcohol-related dementia

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Questions (1)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2

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