Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease and Lou Gehrig’s disease, is part of a larger family of conditions called neurodegenerative diseases. Neurodegenerative diseases are all characterized by the degeneration and death of neurons. These cells, located in the brain and spinal cord, enable many of our most vital functions, including thought, speech, movement, and memory.

One of the most common neurodegenerative conditions is Alzheimer’s disease. According to the Alzheimer’s Association, it is the sixth leading cause of death in the United States. While they are both progressive neurodegenerative diseases, ALS and Alzheimer’s affect very different functions of the central nervous system. ALS is a disease of the motor neurons – the cells responsible for controlling movement and allowing the brain to send signals for movement to the rest of the body. In most cases, it does not affect the brain’s ability to think or remember.

What is Alzheimer’s disease?

Alzheimer’s, unlike ALS, affects cognition – the ability of the brain to regulate functions like memory, speech, and thought. It is the most common form of dementia – a group of neurodegenerative diseases that affect these cognitive abilities. The disease primarily affects people older than 65, although it may be diagnosed in people significantly younger in rare cases. Early symptoms often include:

  • Trouble remembering recent events.
  • Becoming lost or disoriented, even in familiar places.
  • Trouble recognizing familiar people, including family members.
  • Difficulty completing everyday tasks.
  • Misplacing items.
  • Becoming confused about the date or time.
  • Changes in mood or personality.

As the disease progresses, these symptoms will become more severe. Eventually, people with the disease will struggle to recall both recent events and portions of their personal history, recognize their surroundings, and interact with others. The rate of progression is variable – most people with Alzheimer’s live between three to 11 years with the diagnosis, although some may live much longer. In the disease’s late stages, people with Alzheimer’s may also experience a decline in physical abilities like walking, swallowing, or even holding their heads up without support. At this point, people with the disease require round-the-clock care.


Despite both falling under the umbrella of neurodegenerative disease, there is no evidence that ALS and Alzheimer’s disease are connected in any way. In most ALS cases, cognitive function is unaffected – the disease only affects the central nervous system’s ability to control movement. However, there is another form of dementia that can be associated with ALS – Frontotemporal Dementia (FTD). As many as 20% of ALS cases may also involve FTD, and both can be caused by some of the same genetic mutations in certain instances.

Alzheimer’s vs. FTD

FTD involves the degeneration of neurons in the areas of the brain behind the forehead (the frontal lobe) and behind the ears (the temporal lobes). These areas are generally associated with personality, behavior, and language. Alzheimer’s, on the other hand, affects the entire cerebral cortex, or the outermost layer of tissue around the brain. Unlike Alzheimer’s, FTD does not usually affect memory in its earlier stages. Instead, it causes changes in behavior and the ability to speak and understand language. FTD is also much more common in younger people than Alzheimer’s, with onset normally occurring between the ages of 40-65.

There are two more common forms of FTD: behavior variant FTD (bvFTD) and Primary Progressive Aphasia (PPA).

  • bvFTD is primarily characterized by changes in behavior and personality, including increasingly inappropriate behavior, loss of empathy and other social skills, and a general lack of inhibition. 
  • PPA primarily affects language skills. People with PPA may gradually lose the ability to speak, read, or understand language.

ALS and Alzheimer’s: Two Diseases in Need of Effective Treatments

While ALS and Alzheimer’s disease are very different conditions, they share one unfortunate similarity – there are currently no effective treatments to stop or slow progression for most people with either disease. However, there are many investigative treatments for both in clinical trials. 

The ALS Therapy Development Institute (ALS TDI) is dedicated to doing the preclinical research needed to invent and advance many potential ALS drugs to human clinical trials – and we will not stop until there are treatments for everyone with ALS.

To learn more about ALS TDI and our research to end ALS, click here.

What to do Next