What are the 10 Neurodegenerative Diseases?

Understanding Neurodegenerative Diseases: A Guide to 10 Key Disorders

Neurodegenerative diseases are a group of conditions that gradually damage or destroy nerve cells (neurones) in the brain and nervous system. Over time, this leads to problems with thinking, movement, and sometimes mood or behaviour.

These disorders can significantly impact quality of life and currently have no known cures. However, ongoing research continues to uncover new insights into how they develop and how they might be treated.

In this article we’ll take a closer look at 10 major neurodegenerative diseases and review current treatment approaches used to manage their symptoms.

1. Alzheimer’s Disease (AD)

Alzheimer’s is the most common neurodegenerative disease and a leading cause of dementia. It involves the accumulation of amyloid-beta plaques and tau tangles in the brain, leading to memory loss, confusion, and cognitive decline.

Symptoms:

• Reasoning
• Language
• Behaviour and personality
• Spatial understanding
• Memory

Treatment:

There is no cure, but medications like donepezil and memantine help manage symptoms. Newer treatments, such as aducanumab and lecanemab, aim to target amyloid plaques.

2. Parkinson’s Disease (PD)

Parkinson’s affects dopamine-producing neurones in the substantia nigra. It primarily causes motor control problems.

Symptoms:

1.  Motor Symptoms

• Bradykinesia: Slowed movements; feels like weakness but is muscle control loss.
• Resting tremor: Shaking when muscles are relaxed (in 80% of cases).
• Rigidity:
  
  • Lead pipe: Constant stiffness.
  • Cogwheel: Jerky, stop-and-go motion.
• Posture/gait changes: Stooped stance, shuffling walk, reduced arm swing.
• Less blinking, drooling, and soft voice (hypophonia).
• Micrographia: Small, cramped handwriting.
• Hypomimia: Reduced facial expressions.
• Dysphagia: Trouble swallowing.

2.  Non-Motor Symptoms

• Loss of smell (anosmia)
• Sleep issues: REM behaviour disorder, restless legs, PLMD.
• Depression
• Cognitive decline: Dementia, focus problems.
• Autonomic issues:
  
  • Low blood pressure when standing
  • Constipation, urinary problems
  • Sexual dysfunction

Treatment:

The gold standard is levodopa, often combined with carbidopa. Other treatments include dopamine agonists (pramipexole, ropinirole), MAO-B inhibitors, deep brain stimulation (DBS), and physical therapy.

3. Huntington’s Disease (HD)

It is a genetic disorder caused by a mutation in the HTT gene, leading to the degeneration of brain cells.

Symptoms:

1.  Physical Symptoms

• Changes in posture, gait, and movement (voluntary/involuntary)
• Speech, swallowing, and eating difficulties
• Weight loss, weakening the immune system
• Walking issues: stumbling, balance problems
• Rigidity, especially in juvenile HD

2.  Involuntary movements:

• Chorea (spasms, jerks, twitches – most common)
• Akinesia (lack of movement)
• Loss of coordination
• Seizures (more common in juvenile HD)
• Abnormal eye movements
• Dystonia, clonus, Babinski reflex

3.  Behavioural Symptoms

• Depression
• Other mental health issues: OCD, mania, delusions
• Behavioural changes:
  
  • Aggression, irritability, frustration
  • Mood swings, insomnia, hypersomnia
  • Overeating (polyphagia), stubbornness
  • Alcohol-use disorder

4.  Cognitive Symptoms

• Memory loss, confusion, disorientation
• Apathy, lethargy, brain fog
• Hallucinations
• Poor focus, multitasking, and learning
• Reduced organisational and problem-solving skills

Treatment:
 

There is no cure. Tetrabenazine helps manage chorea. Antipsychotic and antidepressant medications are often used. Genetic counselling is critical for affected families.

4. Amyotrophic Lateral Sclerosis (ALS)

Also known as Lou Gehrig’s disease, ALS causes the progressive loss of motor neurones, leading to muscle weakness and atrophy.

Symptoms:

• Trouble walking or doing daily tasks
• Frequent tripping or falling
• Weak legs, feet, or ankles
• Clumsy or weak hands
• Slurred speech or difficulty swallowing
• Muscle cramps and twitches (arms, shoulders, tongue)
• Laughing, crying, or yawning at the wrong time
• Changes in thinking or behaviour

Treatment:

Riluzole and edaravone are FDA-approved to slow progression slightly. Supportive care (ventilation, physical therapy, speech therapy) significantly improves quality of life.

5. Multiple System Atrophy (MSA)

It is a rare condition affecting autonomic functions (like blood pressure and heart rate) and movement. It shares features with Parkinson’s but progresses more rapidly.

Symptoms:

1.  Autonomic Symptoms

• Low blood pressure when standing (orthostatic hypotension)
• Bladder and bowel issues (incontinence)
• Sexual problems (e.g., erectile dysfunction)
• Sleep issues, like REM sleep behaviour disorder and sleep apnoea
• Reduced sweating, dry mouth, and constipation
• Vision problems
• Slow digestion

2.  Cognitive & Emotional Symptoms

• Trouble thinking or focusing
• Depression, anxiety, panic attacks
• Emotional outbursts (crying/laughing at wrong times)
• Suicidal thoughts

3.  Movement Symptoms

i)  MSA-C (cerebellar type):

• Poor coordination (ataxia)
• Clumsy limbs, shaky movements (action tremor)
• Wide, unsteady walking
• Jerky eye movements (nystagmus)

ii)  MSA-P (Parkinsonian type):

• Slowed movement (bradykinesia)
• Muscle stiffness, hunched posture
• Frequent falls
• Slurred or unclear speech

Treatment:

No cure exists. Treatment focuses on symptom management using medications like fludrocortisone (for blood pressure) and levodopa (with limited benefit). Physical therapy is helpful.

6. Frontotemporal Dementia (FTD)

Frontotemporal Dementia (FTD) is a group of brain disorders that primarily affect the frontal and temporal lobes, leading to changes in behaviour, personality, and language. It typically occurs at a younger age than other forms of dementia, often between ages 45 and 65.

Symptoms:

1.  Behavioural Variant FTD (bvFTD)

• Loss of Inhibitions
  
  • Saying rude or inappropriate things
  • Ignoring personal space, touching others inappropriately
  • Risky or impulsive actions (e.g., gambling, shoplifting)
• Apathy
  
  • Lack of motivation
  • Social withdrawal
  • Poor self-care and hygiene
• Loss of Empathy
  
  • Difficulty understanding or caring about others’ feelings
• Compulsive Behaviours
  
  • Repeating actions (clapping, pacing)
  • Strict routines, hoarding, or watching/reading the same things
  • Repeating words or phrases
• Changes in Eating Habits
  
  • Overeating
  • Eating non-food items (pica)
  • Mouth-focused habits (chewing, smoking, etc.)
• Poor Executive Function
  
  • Trouble planning, organising, or solving problems
  • Memory and visual understanding usually stay okay until later stages

Treatment:

There are no disease-modifying treatments. SSRIs and antipsychotics may manage behavioural symptoms. Speech and occupational therapy provide support.

7. Spinocerebellar Ataxia (SCA)

It is a group of inherited disorders affecting the cerebellum, leading to coordination and balance issues.

Symptoms:

• Uncontrolled eye movements
• Poor coordination and balance
• Slurred speech
• Trouble walking
• Difficulty with hand-eye tasks
• Problems with memory or learning

Treatment:

No cure exists. Treatment is symptomatic and includes physical therapy, adaptive devices, and sometimes medications for tremor or spasticity.

8. Lewy Body Dementia (LBD)

It is marked by abnormal deposits of alpha-synuclein (Lewy bodies) in the brain; LBD combines symptoms of dementia and Parkinsonism.

Symptoms:

1.  Movement Symptoms:

• Slow movement
• Muscle stiffness
• Tremors
• Poor balance and frequent falls
• Shuffling walk
• Trouble swallowing
• Fewer facial expressions
• Small, cramped handwriting
• Loss of coordination

2.  Cognitive Symptoms:

• Mental alertness that comes and goes
• Trouble planning, solving problems, or making decisions
• Memory loss (often later in the illness)
• Difficulty focusing
• Trouble understanding visual information
• Sleep problems.
• Mood and behaviour changes.

Treatment:

Cholinesterase inhibitors (like rivastigmine) help cognitive symptoms. Levodopa may help motor symptoms but can worsen hallucinations. Careful medication management is essential.

9. Progressive Supranuclear Palsy (PSP)

It is a rare disease affecting balance, eye movement, and thinking ability due to the accumulation of tau protein.

Symptoms:

1.  Progressive Supranuclear Palsy (PSP)

i)  Early Signs:

• Trouble with balance and frequent falls (often backward)
• Hard to look down
• Staring, wide-eyed look

ii)  Other Symptoms:

• Trouble swallowing
• Stiff muscles, making movement hard
• Slurred or soft speech
• Mood changes (like depression or irritability)
• Personality or behaviour changes (impulsiveness, poor judgement)
• Memory loss or dementia
• Trouble sleeping, including acting out dreams (RBD)
• Sensitivity to bright light

Treatment:

No cure. Some patients respond to Parkinson’s medications. Physical and speech therapy are important for managing symptoms.

10. Corticobasal Degeneration (CBD)

CBD is a rare disorder affecting movement, cognition, and sometimes language, due to abnormal tau protein buildup.

Symptoms:

• Muscle stiffness, tremors, or twitches
• Trouble with small tasks (like using buttons or utensils)
• One limb moving on its own (alien hand)
• Numbness in parts of the body
• Slow or no movement in arms or legs
• Memory loss or thinking problems (dementia)
• Needing help to walk
• Mood or behaviour changes (e.g., apathy, irritability, poor focus)

Treatment:

There are no disease-modifying therapies. Levodopa and botulinum toxin may provide limited symptom relief. Supportive care is crucial.

What is the treatment for neurodegenerative disease?

While cures for most neurodegenerative diseases remain elusive, various treatments aim to manage symptoms, slow progression, and improve quality of life.

1.  Gene Therapy

• Delivers therapeutic genes to correct or modify cellular functions.
• Uses vectors (e.g., iMRI-CED) for targeted delivery.
• Promising in preclinical trials, though challenges like leakage remain.

2. Immunotherapies

• Targets misfolded proteins and inflammation via monoclonal antibodies.
• Has potential, but challenges exist due to disease complexity.
• Novel immune targets may offer innovative treatment options.

3. Molecular Targeted Therapies

• Focuses on disease-specific pathways (e.g., protein misfolding, inflammation).
• Shown effective in animals; yet to show significant efficacy in humans.
• Requires better clinical outcome measures and preclinical replication.

4. Pharmacological Therapy

• Includes anti-beta-amyloid and nerve growth factor agents and antioxidants.
• Used for diseases like AD and PD (e.g., dopamine uptake inhibitors).
• Targets include neurotransmitters, oxidative stress, and inflammation.

5. Symptomatic Therapies

• Approved drugs (e.g., donepezil, memantine) improve cognition in AD.
• Enhance cholinergic function and reduce behavioural symptoms.
• Imaging tools aid in tracking treatment effects.

6. Mesenchymal Stem Cell (MSC) Therapy

• MSCs aid tissue repair via differentiation and immunomodulation.
• Applied in PD, AD, ALS, HD, and MS with early-stage trial success.
• MSC therapies are investigational and not yet proven effective in large-scale trials.

7. MSC Secretome Therapy

• Uses bioactive molecules (e.g., cytokines, growth factors) secreted by MSCs.
• Offers non-invasive therapeutic potential for neural repair.
• Paracrine signalling helps in reducing apoptosis and inflammation.

8. Extracellular Vesicles (EVs)

• EVs (exosomes, microvesicles, apoptotic bodies) transport signalling molecules.
• Derived from various cells; difficult to classify due to size/marker overlap.
• Show promise as delivery systems in regenerative therapies.

Neurodegenerative diseases pose complex and lifelong challenges, but advances in research and therapy are opening new doors for better management and improved quality of life.

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