Alzheimer’s Disease 

Definition:
Primary neurodegenerative disease that causes progressive cognitive deterioration, episodic memory loss, and language and planning defect, with no sensory or motor defect.  

  • Characterized byβ-amyloid deposits and neurofibrillary tangles in the cerebral cortex and subcortical gray matter.

Epidemiology:

  • Most common type of dementia accounting for 66% of all dementia cases. 

Risk Factors:

Study guide:

Pathophysiology:

  • A β amyloid is derived from APP (amyloid precursor), which is coded on chromosome 21, through alpha and beta cleavage. 

  • Amyloid may also deposit around the vessels (amyloid angiopathy), which increase the risk of hemorrhage.

Neuritic plaques:

A beta Amyloid + entangled neuritic processes 

Neurofibrillary tangles (intracellular):

hyperphosphorylated tau protein

Loss of cholinergic neurons in the neucleus basalis of Meynert in the basal forebrain

​Clinical Presentation:

Type

Examples

Early+stages

  • Memory impairment

  • Language impairment

  • Agnosia: failure to recognize objects

  • Apraxia: inability to learn new skills 

Intermediate+ stages

  • Memory impairment

  • Behavioral changes: hostility, aimless actions, and  inappropriate judgment

  • Personality changes: irritability, anxiety, and depression

Late+stages

  • Daily activities are markedly impaired

  • Loss of episodic and distant memories

Advanced+stages

  • Inability to swallow

  • Debilitation

  • Increased risk of malnutrition, infections, and aspiration (common cause of death)

Diagnosis:

  • DX is mainly through clinical history and evidence of significant memory impairment. 

  • Others:

CT Scan:

  • Non-specific

  • Diffuse atrophy of the brain especially in the temporal lobe

  • Compensatory enlargement of the ventricles

MRI:

  • Atrophy of the temporal lobes and hippocampi.

Other Tests: 

to exclude other types of  dementia

  • Please refer to the  dementia  summary file

Management:

  • Cholinesterase inhibitors: (donepezil, rivastigmine and galantamine):

             -> 1st line therapy for AD

  • NMDA receptor antagonist: (memntine).

  • Dietary supplements (ginko, lecithin).

  • Vitamen E in some studies shown to slow the disease progression.


Prognosis: 

  • If AD left untreated, the patient will be bedridden and mute in just 5-10 years.

References:

  • Agabegi, Steven S, Elizabeth D Agabegi, and Adam C Ring. Step-Up To Medicine. Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins, 2013. Print.

  • Kumar, Parveen J, and Michael L Clark. Kumar & Clark's Clinical Medicine. Print.

  • Hauser, Stephen, and Scott Josephson. Harrison's Neurology In Clinical Medicine. 3rd ed. McGraw Hill. Print.

  • Yogarajah, Mahinda. Neurology. Edinburgh: Mosby/Elsevier, 2014. Print.

  • Latest Facts & Figures Report | Alzheimer's Association,. 'Latest Alzheimer's Facts And Figures'. N.p., 2013. Web. 23 Sept. 2015.

  • Sattar, Husain A. Fundamentals Of Pathology. Chicago: Pathoma.com, 2011. Print.

  • Le, Tao, Vikas Bhushan, and Herman Singh Bagga. First Aid For The USMLE Step 2 CK. New York: McGraw-Hill Medical, 2010. Print.

  • Alzheimer's Disease,. 'Creutzfeldt-Jakob Disease'. N.p., 2013. Web. 24 Sept. 2015. (Figure 1).

  • Frontalcortex.com,. 'Alzheimer's Disease, Hippocampus, H&E 200X'. N.p., 2015. Web. 24 Sept. 2015. (Figure 2).

  • MD, Edward. 'Cell Injury'. Library.med.utah.edu. N.p., 2015. Web. 24 Sept. 2015. (Figure 3).

First author:          Roaa Amer

Second authors :  Abdullah AlAsaad

                            Lama AlLuhaidan

Reviewers:            Abdulrahman Al Nasser

                            Bayan AlZomaili

Format Editor :    Adel Yasky 

Audio recording:
- Read by: Nada Alhassan
- Directed by: Rana Alzahrani
- Audio production: Bayan Alzomaili

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