When describing types of dementia we often read the phrase "Alzheimer's and related dementias." I am going to take this opportunity to provide an up-to-date overview of some of the very common "related dementias." 


It has been estimated that there are some 70 to 100 different diseases or conditions that cause dementia symptoms. Remember, dementia is simply defined as impairment in thinking, remembering, and reasoning to such a significant level that it impacts function and safety. A person experiencing dementia symptoms should see a specialist which is often a geriatric psychiatrist, neurologist, or geriatrician, to identify the cause of these symptoms.


Dementia causes can be reversible or irreversible and progressive. Many of the dementia types we see in the elderly that we serve are irreversible and progressive, such as Alzheimer's disease. This article provides a summary of some of the very common dementia diseases that we see in our settings, in addition to Alzheimer's type.


I have successfully utilized the Allen model for all of these diagnoses. The Allen model is a functional cognitive assessment method and therefore we are able to identify a cognitive level through observation of function even though the cognitive impairments behind the functional loss may be a little different for each disease process. When using the Allen method for cognitive assessment we are not seeking to identify and measure the impairment in each cognitive area but instead we are looking at the collective impact of cognitive loss on function.


Cognitive change is often not the only symptom of these disease processes that impact function. A therapist must take into account many of the complicating performance component factors when attempting to identify a person's cognitive level and when making a treatment and education plan.


Other complicating symptoms can include:

  • Fluctuations in performance
  • Fluctuations in level of alertness and fatigue
  • Behavior problems such as anxiety, apathy, or depression
  • Communication loss
  • Hallucinations and delusions
  • Parkinsonism and other physical challenges

These complicating factors are just one reason why our services are needed. The complications that accompany many of these common dementias make it even more difficult for a family or professional caregiver to identify and promote best ability. And of course when best ability is not fostered, this can cause burnout and stress for the caregiver, behavior problems, and many other problems for the client.


Alzheimer's Related Dementias







  • Second or third most common dementia type
  • Step-wise progression
  • Cause is impaired blood flow to the brain
  • Complete blockage of large blood vessel causes a stroke
  • Small blood vessel blockages combine over time to cause a series of small strokes or infarcts
  • Narrowing of vessels can also cause impaired blood flow
  • Various cognitive impairments including confusion, difficulty concentrating, planning, and following instructions
  • Memory problems depending upon region of brain affected
  • Communication deficits depending upon region of brain affected
  • Physical problems depending upon region of brain affected
  • Functional loss
  • No cure
  • Medications used to help those with Alzheimer's disease (AD) appear to help  such as cholinesterase inhibitors (i.e. Aricept) and Namenda
  • OT/PT/ST to identify remaining abilities to facilitate BATF, train/educate caregivers, adapt to current level and minimize functional loss associated with impairment, introduce compensatory strategies for loss of function, mobility and communication as able, and prevent falls and other complications


  • Second or third most common dementia type
  • Progressive
  • Caused by abnormal protein deposits in nerve cells in the brain called "Lewy bodies"
  • About 50% of cases are related to a condition called Rapid Eye Movement (REM) sleep disorder


  • Cognitive impairments including memory loss, poor judgment, confusion and other cognitive symptoms that overlap with AD
  • Fluctuations during the day or day to day in cognition and alertness
  • Excessive daytime drowsiness
  • Behavior worse at night
  • Parkinsonism such as rigidity and tremors
  • Visual hallucinations (often small animals or people)
  • Functional loss
  • No cure
  • Responds well to cholinesterase inhibitors – used to address the cognitive and alertness problems as well as hallucinations and behaviors
  • May require medications to address the movement disorders (however may increase confusion, hallucinations and delusions)
  • Adverse reactions to antipsychotic drugs
  • OT/PT/ST as described above. Also focus on identification of pattern of "best ability" due to fluctuations and behavior reduction strategies.
  • Address sleep problems through increased activity and exercise, reduction of caffeine, and establishing a normal sleep/wake routine


  • Umbrella term for a group of rare disorders that impact the frontal and temporal lobes of the brain including Picks Disease and Primary Progressive Aphasia
  • May see shrinkage of these lobes in imaging
  • Progressive and rapid onset
  • Typically occurs between ages 40 and 70
  • Between 20% and 50% have a family history of some type of dementia
  • Early symptoms can include changes in personality and social functioning (i.e. loss of interest, blunt affect, may make socially rude comments)
  • First cognitive losses often involve impairment in judgment and planning. Memory problems are not as prominent in the early stages
  • Early impairments may be the loss of the ability to use and understand language
  • May have increased appetite and gain weight
  • Symptoms depend upon which lobe is involved and to what extent
  • Functional loss
  • No cure
  • Very little treatment available to slow the progression
  • Treatment focus is related to symptom management including use of antipsychotics and use of tranquilizers
  • OT/PT/ST as described above. Also, emphasis on ST for communication loss and team approach for behavior management and caregiver education.


To add to the challenge, mixed dementias also occur. For example, Alzheimer's disease and vascular dementia often occur at the same time. Brain autopsies have shown up to 45 percent of people with dementia have signs of both Alzheimer's and vascular dementia.


Clearly, Alzheimer's and related dementias impact on function, safety, and communication ability. There is no cure for these diseases and medications are only partially successful. Therefore, therapy must be involved to identify and maximize remaining abilities while helping to manage the deficits. This requires the therapist to use an excellent cognitive assessment followed by establishment of techniques which are matched to the needs and cognitive capabilities of the client, along with caregiver education, training, and support. Families and professional caregivers do not know how to identify and promote best ability. Families and caregivers do not know how to customize, adapt, and implement the many general recommendations and techniques found on websites and in books. Successful strategies can only occur once the "can do," "will do," and "may do" components have all been assessed and considered. Once again, therapy has a significant role to fill.


Sources:  (accessed on May 5, 2008)  (accessed on May 5, 2008)