Daughter embracing her mother in a wheelchair outsideShare on Pinterest
FluxFactory/Getty Images

Frontotemporal dementia (FTD) is a collection of neurological disorders involving changes to the frontal and temporal lobes of the brain. These lobes are generally associated with behavior, personality, and language.

This type of dementia is one of the most common types of dementia in people less than 65 years old. It can affect memory, emotions, impulse control, social interaction, and your ability to effectively speak.

Amyotrophic lateral sclerosis (ALS) is a rare neurological disease also known as Lou Gehrig’s disease. It affects the nerve cells controlling muscle movement throughout the body.

Although the two conditions affect the body and brain in very different ways, they appear to share a common disease pathway. Many people with ALS also develop FTD.

Although not everyone with ALS develops FTD, a 2020 research review suggests that as many as half of all people with ALS go on to develop the type of dementia associated with FTD.

That same report also notes that about 30 percent of people with FTD also develop motor control problems, including lack of coordination or jerky and unsteady body movements.

Many studies in recent years have highlighted the genetic risk factors that ALS and FTD share, as well as the common ways both diseases develop in the brain. When the two diseases occur together, researchers label the condition as ALS-FTD.

A 2017 study suggests that ALS-FTD may be an autophagy disease. Autophagy refers to the process in which cells destroy and recycle certain proteins and other parts in order to create or preserve healthy cells.

In the case of ALS-FTD, problems with autophagy may specifically interfere with the processing of ribonucleic acid (RNA). This acid in the chromosomes is involved in sharing information about protein structure from one cell to another. ALS-FTD also may impair autophagy by disrupting the stability of proteins in brain cells.

According to a 2020 review, an especially active area of research in ALS-FTD is the role of TAR DNA-binding protein 43 (TDP-43). Deposits of this protein build up in the nerve cells of individuals with ALS and FTD. They may be responsible for the death of those cells by destabilizing the RNA.

There is currently no cure for ALS or FTD. But a 2019 study suggests that modifying the structure of TDP-43 may interfere with its ability to bind RNA and prevent the loss of nerve cells.

Additionally, according to a 2019 review, clinicians widely believe that the C9orf72 gene plays a role in ALS-FTD. A 2019 study cites research that the repeated expansion of this gene is the most common cause of familial and sporadic ALS-FTD to date. It accounts for roughly 40 percent of familial ALS and 5 to 10 percent of sporadic ALS.

ALS mainly affects muscle control, often sparing cognition and memory. FTD, however, tends to affect thinking skills, mood, and behavior.

Let’s look at the symptoms of ALS and FTD in more detail.

ALS symptoms

The earliest signs of ALS often include muscle twitches or cramps, as well as muscle weakness affecting the limbs, neck, or diaphragm.

As the disease progresses, other common ALS symptoms include:

  • difficulty speaking clearly
  • trouble chewing and swallowing
  • difficulty walking without assistance
  • loss of coordination
  • muscle tightness
  • breathing problems that can sometimes lead to the use of a ventilator

Because many people with ALS tend to retain their memory and thinking skills, they are often keenly aware that their motor control is going away, as is their independence. This can sometimes lead to depression or anxiety.

FTD symptoms

The earliest FTD symptoms can include changes in behavior, such as withdrawing from or avoiding social situations. Difficulty speaking is another early symptom.

Other common FTD symptoms include:

  • difficulty planning and prioritizing tasks and responsibilities
  • acting impulsively
  • repeating the same words and activities several times in a row
  • withdrawal from family, friends, and activities they once enjoyed
  • difficulties with speech and understanding what others are saying

Although ALS and FTD may follow similar disease pathways, scientists are not yet sure why people develop one or both of these progressive diseases.

ALS causes

The exact causes of ALS remain unknown, although researchers believe that the disease may be the result of an interplay between genetic factors and environmental influences.

A 2020 review notes that more than 20 gene mutations are associated with ALS, but that only about 10 percent of all ALS cases are hereditary. The majority of people with ALS have no family member with the disease.

FTD causes

Similarly, the causes of FTD are unknown, though researchers are investigating genetic mutations that may play a role. According to the National Institute on Aging, the genetic mutations that may contribute to FTD include:

  • Tau gene. This leads to an unusual buildup of the tau protein — also a hallmark of Alzheimer’s disease.
  • GRN gene. This is associated with an unusual buildup of the protein TDP-43, also implicated in both FTD and ALS.
  • C90RF72 gene. This is also associated with the development of ALS and FTD.

Neither condition has a cure or a way to slow disease progression, but there are treatments that can help manage certain symptoms.

ALS treatments

  • Riluzole and edaravone. Riluzole (Rilutek) and edaravone (Radicava) are two drugs approved by the Food and Drug Administration (FDA) to treat ALS. Riluzole helps protect motor neurons by decreasing glutamate, a chemical in the brain that carries messages between nerve cells and motor cells. Edaravone acts as an antioxidant, protecting healthy cells from oxidative stress.
  • Physical therapy and speech therapy. These therapies may also be helpful for people with ALS, especially early in the disease.
  • Breathing help. Breathing support through a face mask, nasal mask, or helmet is also a common treatment. Known as noninvasive ventilation, this type of breathing support has become “an important cornerstone of symptomatic treatment” for ALS, improving survival and quality of life, according to 2019 research.
  • Feeding tube. As ALS progresses, eating can become challenging. For people with ALS who are at high risk of malnutrition, a 2020 study recommends percutaneous endoscopic gastrostomy (PEG) tube placement. This helps to maintain nutrition and provides an alternative route for medications.
  • Pain management. The ALS Association points to over-the-counter pain medications, as well as other options such as acupuncture and focused injections in particular areas that are experiencing the pain. People with ALS are encouraged to talk with their doctors.

FTD treatment

With FTD, treatment can include medication as well as interventions to help people cope with the symptoms of dementia:

  • Medication. This may include a type of medication known as selective serotonin reuptake inhibitors (SSRIs), most often used to treat depression and some other mental health conditions. For FTD, these SSRIs may help manage some extreme behavioral symptoms.
  • Routine. Creating a regular schedule and simplifying the person’s daily routine can be helpful.
  • Speech and physical therapy. These therapies may be necessary in some cases, depending on the nature and severity of symptoms.
  • Patience. Since symptoms can be distressing, try to support you loved one as much as possible without challenging or upsetting them.

According to the National Institute of Neurological Disorders and Stroke (NINDS), the average life expectancy for ALS is 3 to 5 years after it begins. About 1 in 10 people with ALS live at least 10 years after symptoms start.

This disease usually affects one part of the body first, and this initial area can differ from one person to the next. The upper limbs may be affected before the legs, or vice versa. But eventually, ALS affects the entire body. Respiratory failure is often the cause of death, typically within 5 years of the first symptoms appearing, according to the NINDS.

As for FTD, according to the NINDS, the outlook for people with FTD is “poor.” The NINDS notes that the disease “progresses steadily and often rapidly.” The range can be 3 to 10 years, and eventually, some people will need 24-hour care and monitoring at home or in a residential healthcare setting.

Navigating your way through the ALS journey can be difficult. But many resources exist for support and help for family, friends, caretakers, and those living with ALS.

  • The NINDS offers this fact sheet for more detailed information about the condition and treatment options, as well as this resource specific to FTD.
  • The ALS Association was founded in 1985 and is the only national nonprofit focused solely on ALS. The organization has many resources, including state chapters and local support information for each person in the ALS journey.
  • The Centers for Disease Control and Prevention (CDC) has a list of many different organizations and informational sites on ALS.
  • Patients Like Me is an online community for people with different conditions, including ALS. It helps people learn more about ALS, find support, and share their stories and experiences with other people affected by ALS. Registration is free.

Remember, you are not alone.

Research from 2020 suggests as many as half of all people with ALS may also develop FTD. This can further complicate a condition that’s already very challenging for people living with it and their caregivers.

Both ALS and FTD appear to have overlapping symptoms and causes. ALS is mainly a disease affecting motor control, while FTD is a disease that interferes with thinking skills and behavior. Neither condition has a cure. But there are medications as well as other ways to slow down the progression and manage symptoms as they appear.