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Amyotrophic Lateral Sclerosis - Frontotemporal Spectrum Disorder (ALS-FTSD): Causes, Symptoms, Diagnosis, and Treatment.

Published on Sep 29, 2022 and last reviewed on Feb 20, 2023   -  5 min read


This term describes the range of behavioral and cognitive impairments in patients suffering from overlapped ALS and FTD. Read this article to know more.

What Is ALS?

Known as amyotrophic lateral sclerosis (ALS), it is a condition that causes progressive degeneration of the motor neurons in the brain and the spinal cord. When the motor neurons get affected, the brain loses its ability to initiate and control voluntary muscle movement, eventually leading to the patient's demise.

Our body has two different types of nerves-

  • Sensory Nerves- They carry signals from the body to the brain to help us with sensory functions like smelling, touching, listening, etc.

  • Motor Nerves- They carry signals from the brain to the muscles and organs in the body to perform functions like moving, talking, breathing, etc.

ALS exclusively affects the motor nerves in the body, initially causing muscle weakness in the hands and limbs and then progressing to other parts of the body, eventually debilitating normal motor functions like chewing, swallowing, speaking, etc. The main cause of death in patients suffering from ALS is a respiratory failure which happens due to paralysis of respiratory muscles.

What Is FTD?

  • It means frontotemporal dysfunction (FTD), which is also a degenerative condition of the brain characterized by a change in behavior, personality, thinking, judgment, etc. Although the brain is one organ structurally, it is divided into the forebrain, midbrain, and hindbrain.

  • There are different structures in the forebrain, for example- the cerebrum, thalamus, hypothalamus, etc. The cerebrum is the largest part of the brain and is further divided into four pairs of lobes; they are-

    • Frontal Lobes- Responsible for cognitive functions and control of voluntary movement.

    • Temporal Lobes- It processes memories and integrates them with the sense of taste, sound, sight, and touch.

    • Occipital Lobes- It is primarily responsible for vision.

    • Parietal Lobes- It processes information about temperature, taste, touch, and movement.

  • In patients with FTD, the frontal lobe and the temporal lobes shrink (atrophy) due to genetic mutations (changes in the structure of the genes); based on the extent of the atrophy, the symptoms can range from being emotionally indifferent to losing the ability to use language.


ALS manifests as a pure motor syndrome in many patients, but in a few of them, it is seen to coexist with dementia (especially frontotemporal dementia). When the genes that are responsible for ALS and FTD overlap, then the resultant neurophysiological and neuropsychological symptoms fall under a wide range collectively known as an amyotrophic lateral sclerosis-frontotemporal spectrum disorder (ALS-FTSD).

What Causes ALS-FTSD?

With the recent advances in genetic sequencing, it is now recognized that mutations in the C9orf72 gene are responsible for ALS and FTD individually as well as for ALS-FTSD. This has disproved the long-term belief that ALS is purely a movement-related disorder and FTD is purely a cognition-related condition. There are other types of genes that cause these conditions, like GRN genes and Tau genes (also known as MAPT genes), but the overlapping mechanism is still being researched.

What Are the Symptoms of ALS-FTSD?

Symptoms of FTD are noticed, first followed by ALS symptoms; they are-

FTD Symptoms- They vary from person to person. Some of the common ones are-

  1. Dramatic personality changes like excessive swearing, increased interest in sex, stealing, and deterioration in personal hygiene habits.

  2. Inappropriate repetitive social behavior and impulsiveness.

  3. Emotionally indifferent and lacking empathy.

  4. Lack of enthusiasm, interest, concern (apathy).

  5. Loss of energy and motivation.

  6. Decreased self-awareness.

  7. Agitation.

  8. Frequent mood changes.

  9. Trouble in organizing and planning.

  10. The inability to understand and use language also includes difficulty in naming objects, expressing words, etc.

  11. Hesitation before speaking and reduced communication.

  12. Easily distracted.

  13. Increasingly becoming dependent.

  14. Eating inedible objects and constantly putting things in the mouth.

ALS Symptoms- The early symptoms of the condition are-

  1. Twitching and cramping in the muscles of the hands and feet.

  2. Impairment (loss of control) in the use of arms and legs.

  3. Tripping and falling.

  4. Persistent fatigue with constant clumsiness.

  5. Uncontrollable fits of laughter and crying.

  6. Speech impairment and trouble in voice projection.

As the disease progresses, the associated symptoms become severe; they are-

  1. Dysphagia (difficulty in swallowing).

  2. Dyspnea (difficulty in breathing).

  3. Paralysis.

For initial diagnostic purposes, a combination of behavioral and cognitive changes is sufficient to meet the criteria for ALS-FTSD.

How Is ALS-FTSD Diagnosed?

Diagnosing ALS-FTSD is complicated because a few of the symptoms mimic depression which can mislead the diagnosis. Also, the FTD symptoms appear first in order in ALS-FTSD; this will undermine ALS due to its delayed onset.

Family members play an important role in the initial diagnosis; they are the first ones to observe the changes and can communicate the same to the clinician. The clinician will need additional information to further the diagnosis, and the discussion will include the following details-

  • Current health problems and previous medical history.

  • Family’s medical history.

  • Current medication.

After obtaining the information, the clinician will conduct different tests for differential diagnosis. They will include one or a couple of the below-mentioned tests-

  • Electrodiagnostic tests such as an electromyography (EMG) or a nerve conduction velocity (NCV) test.

  • Blood and urine tests to check for heavy metals, thyroid levels, etc.

  • A thorough neurological and neuropsychiatric examination.

  • X-rays, including magnetic resonance imaging (MRI).

  • Myelogram of the cervical spine.

  • Spinal tap to check for infections and biomarkers in cerebrospinal fluid.

  • Genetic testing.

Since the symptoms are nonspecific, there is no single test for diagnosis of ALS-FTSD; as of now, the final diagnosis depends on the information provided by the family, tests, and the expertise of the clinician.

How Is ALS-FTSD Treated?

  • At present, there is no known cure for ALS-FTSD; medications like Riluzole and Rasagiline have been approved by the FDA (Food and drug administration) to slow the progression of the ALS part of the condition. There is no medication for the frontotemporal dysfunction associated with ALS-FTSD; symptomatic treatment has been attempted with limited success.

  • Patients experience a rapid decline in their physical and cognitive abilities, and complete degeneration can occur as quickly as two years to three years as opposed to the five years to ten years span seen in other types of FTD.

  • Physical and speech therapy can help relieve symptoms to a certain extent, but eventually, the patient will need wheelchairs and speech synthesizers to move and communicate. The ALS part of the condition will make it difficult for the patient to chew and breathe and will require the support of a ventilator for survival.


Family or caregivers play an important role in handling patients diagnosed with ALS-FTSD, long-term management of the conditions should involve a team of experts who will help to handle difficult medical and emotional challenges. A multidisciplinary approach comprising neuropsychologists, speech therapists, occupational therapists, and physical therapists is needed to handle the palliative care of patients with ALS-FTSD.

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Last reviewed at:
20 Feb 2023  -  5 min read




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