Alzheimer disease type 4




A degenerative brain disease characterized primarily by progressive dementia. Type 4 has an early onset (starts before the age of 65). It is caused by mutations in the PSEN2 gene which results in the production of a toxic protein (amyloid beta peptide) in the brain which collects into clumps (amyloid plaques) in the brain. These plaques cause damage to nerve cells in the brain.


  • Dementia
  • Gradual memory loss
  • Gradual loss of judgment
  • Gradual loss of ability to function
  • Forgetfulness
  • Confusion
  • Gradual loss of ability to perform familiar routine
  • Gradual loss of ability to recognize familiar faces
  • Gradual loss of ability to recognize familiar places
  • Gradual loss of ability to remember names of objects
  • Gradual loss of ability to feed oneself
  • Gradual loss of ability to dress oneself
  • Personality changes
  • Behavioral changes
  • Increasing inability to interact socially
  • Agitation
  • Restlessness
  • Withdrawal
  • Speech problems
  • Muscle twitching
  • Muscle spasms


The cause of Alzheimer’s disease is unknown; however, several factors are thought to be implicated in this disease. These include neurochemical factors, such as deficiencies in the neurotransmitter acetylcholine, somatostatin, substance P, and norepinephrine; environmental factors; and genetic immunologic factors.

However, some researcher believe that the early-onset, autosomal dominant form of AD is caused by changes (mutations) one of three different genes: APP, PSEN1, and PSEN2. The condition is inherited in an autosomal dominant manner.


course of disease can continue for up to 25 years


There is no cure for AD. Treatment is supportive and based on the signs and symptoms present in each person. However, therapy consists of attempts to slow disease progression, manage behavioral problems, modify the home environment, and elicit family support. Some medications have proven helpful. Tacrine, a centrally acting anticholinesterase agent, is given to treat memory deficits. It has slowed progression of the disease and improved cognitive function in some patients. Other agents include donepezil and rivastigmine. Underlying disorders that contribute to the patient’s confusion, such as hypoxia, are also identified and treated.


  • NIH