20B. Alzheimer disease (AD)

Definition and epidemiology

Alzheimer disease is the most common neurodegenerative disease and the cause of 2/3 of all cases of dementia.

Risk factors

  • Old age
  • Family history
  • Head trauma
  • Vascular risk factors
  • APOE e4 genotype

Protective factors

  • Higher education
  • Good diet
  • Exercise
  • Statins

Pathomechanism

Transmembranous APP is cleaved into Aβ peptides, which aggregate and form amyloid plaques extracellularly, which may have a neurotoxic effect.

Hyperphosphorylated tau protein in the cells form neurofibrillary tau tangles, which may have a neurotoxic effect.

These changes begin in the limbic structures and spread from there, eventually reaching the cortex. These changes can be staged according to the Braak staging.

Clinical features

Patients initially have impairment of memory and learning. Later, impairment of executive function, perceptual motor ability and language occurs.

Diagnosis and evaluation

First, the diagnosis of dementia must be established, with tests like MMSE or the clock-drawing test. Typical clinical features and a typical clinical course is usually enough for diagnosis.

We can perform amyloid PET scan, which shows the amyloid plaques in the brain. We can also measure amyloid plaques or phosphorylated tau tangles in the CSF.

Only an autopsy can truly confirm whether the condition was Alzheimer or not.

Treatment

No treatment is curative, but they can slow the progression. Anticholinergic drugs and amantadine can be used.


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21A. Meningiomas

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