Shared genetic pathways and overlapping processes in the brain may help explain the connection between ALS and dementia, but more research will help fully understand the link.

Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease, is a progressive neurodegenerative disorder. ALS causes decreased muscle function and control. Over time, the loss of motor neurons in your central nervous system (CNS) can cause muscle weakening, atrophy (wasting away of a body part or tissue), and eventual paralysis.

Many people with ALS also experience dementia. Dementia is a broad term for a significant decline in cognitive (thinking) abilities like memory, language, and reasoning. The exact link between these conditions isn’t fully understood, however genetics and disease processes seem to play a role.

ALS and dementia are two different conditions, often occurring together. But the exact prevalence of co-occurring (comorbid) ALS and dementia isn’t known. More large-scale population-based research is needed to help understand the precise rates of comorbidity.

ALS Association suggests that 50% of people with ALS experience mild to moderate cognitive and/or behavioral damage, and 20% meet the diagnostic criteria for dementia.

Frontotemporal dementia (FTD) is the most common type of dementia linked with ALS. Research suggests that 15% of people with FTD also live with ALS.

FTD refers to specific conditions of dementia affecting the frontal and temporal lobes of the brain. These regions control the behavior, personality, language, emotions, and decision making.

Research shows ALS and FTD share many genetic pathways causing both conditions. ALS and FTD occur due to the mutation of the C9ORF72 gene.

Unusual protein TDP-43 buildup in the CNS occurs in both ALS and FTD. When TDP-43 forms clumps, it disrupts the usual neuron function and causes neuronal damage.

These shared pathways and processes cause the overlap between ALS and FTD, but more research is necessary to understand the relationship fully.

Dementia and ALS can share overlapping symptoms, but important differences set them apart.

ALS affects your motor neurons in the CNS (your brain and spinal cord), while dementias like FTD affect multiple types of neurons in various regions of the brain.

The primary symptoms of ALS are related to muscles, including:

The primary symptoms of dementia are cognitive, meaning they affect the ability to think. Though they can also affect physical function, but vary depending on the areas of the brain affected.

Symptoms include:

Both ALS and dementia can cause fatigue and changes in movement, but ALS involves progressive muscle weakness and atrophy, which are not typical symptoms of dementia.

Memory loss is another area of differentiation. In other types of dementia, people report memory loss as one of the most common symptoms. In FTD and ALS, cognitive changes are more likely to affect your executive functions.

Executive functions involve processes that help higher-level thinking, such as reasoning, emotional regulation, and multitasking.

FTD and ALS may affect memory, but it is less common in dementia-like Alzheimer’s disease.

Does everyone with ALS lose the ability to think?

Not everyone with ALS will experience a decline in the ability to think, and cognitive impairment in ALS does not necessarily show ALS severity.

Some researchers believe ALS with certain types of FTD may be variants of ALS and not the natural result of progressive neurodegeneration.

Treating ALS and dementia together requires a multidisciplinary approach that considers the complexity of both conditions.

Depending on your symptoms and severity, your medical team may include neurologists, psychologists, physical therapists, and speech pathologists.

You can manage motor symptoms of ALS through supportive therapies, like physical therapy, to help maintain your muscle strength and function as long as possible.

Riluzole, Edaravone, and sodium phenylbutyrate are Food and Drug Administration (FDA)-approved medications to help slow the degeneration of neurons in ALS.

As ALS advances, you may also benefit from using assistive devices like wheelchairs, communication supports, or feeding tubes.

You can manage cognitive impairment and dementia in ALS through supportive care focussing on comfort, maintaining quality of life, and promoting mental well-being. Working closely with a mental health professional can help develop coping strategies and maintain a positive outlook.

You can also manage the symptoms of dementia through occupational therapy, speech therapy, and physical therapy. These therapies are also applicable for treating ALS.

ALS and dementia are separate conditions that usually occur together. Research is ongoing to understand the relationship between the two. Experts have identified some common genetic pathways and disease processes contributing to overlapping symptoms.

If you receive a diagnosis of ALS and dementia, you’ll work closely with a team of medical professionals to maintain your muscle strength and function, while learning strategies to adjust and cope with the cognitive changes that you’re experiencing.