Therapeutic agents for neurodegenerative diseases

1. A method of treating a neurodegenerative disease or one or more symptoms associated with a neurodegenerative disease in a subject in need thereof comprising:

administering a therapeutically effective amount of acetyl-leucine or a pharmaceutically acceptable salt thereof to the subject for a duration of at least 3 months,

wherein the neurodegenerative disease is not cerebellar ataxia or Niemann-Pick Type C,

wherein the neurodegenerative disease is chosen from Alzheimer's disease, amyotrophic lateral sclerosis (ALS), multiple system atrophy type P (MSA-P), multiple system atrophy type C (MSA-C), frontotemporal dementia with parkinsonism, progressive supranuclear palsy, corticobasal degeneration, Lewy Body dementia, Parkinson's Disease, and ataxia telangiectasia (Louis Barr disease), and

wherein the therapeutically effective amount of acetyl-leucine or pharmaceutically acceptable salt thereof is administered at least two times a day to achieve a total daily dose of from about 500 mg to about 15 g.

2. The method according to claim 1 , wherein the neurodegenerative disease is associated with lysosomal dysfunction.

3. The method according to claim 2 , wherein the neurodegenerative disease associated with lysosomal dysfunction is chosen from ALS, MSA-P, MSA-C, frontotemporal dementia with parkinsonism, progressive supranuclear palsy, Alzheimer's disease, and Louis Barr disease.

4. The method according to claim 1 , wherein the neurodegenerative disease is chosen from progressive supranuclear palsy, Parkinson's Disease, and Louis Barr disease.

5. The method according to claim 1 , wherein the subject has been found to have a genetic and/or biochemical marker of the neurodegenerative disease.

6. The method of claim 1 , wherein treating is delaying onset of the neurodegenerative disease or one or more symptoms of a neurodegenerative disease that would otherwise be expected to manifest according to typical disease progression in the subject.

7. A method of treating a neurodegenerative disease or one or more symptoms associated with a neurodegenerative disease in a subject in need thereof comprising:

administering a therapeutically effective amount of the acetyl-leucine or a pharmaceutically acceptable salt thereof to the subject for a duration chosen from at least about 3 months, at least about 6 months, at least about 1 year, at least about 2 years, and at least about 5 years,

wherein the neurodegenerative disease is not cerebellar ataxia or Niemann-Pick Type C, and

wherein the neurodegenerative disease is chosen from Alzheimer's disease, amyotrophic lateral sclerosis (ALS), multiple system atrophy type P (MSA-P), multiple system atrophy type C (MSA-C), frontotemporal dementia with parkinsonism, progressive supranuclear palsy, corticobasal degeneration, Lewy Body dementia, Parkinson's Disease, and ataxia telangiectasia (Louis Barr disease).

8. A method of delaying progression of a neurodegenerative disease or one or more symptoms associated with a neurodegenerative disease in a subject in need thereof over time as compared to typical disease progression comprising:

administering a therapeutically effective amount of the acetyl-leucine or a pharmaceutically acceptable salt thereof to the subject for a duration chosen from at least about 3 months, at least about 6 months, at least about 1 year, at least about 2 years, and at least about 5 years,

wherein the neurodegenerative disease is not cerebellar ataxia or Niemann-Pick Type C, and

wherein the neurodegenerative disease is chosen from Alzheimer's disease, amyotrophic lateral sclerosis (ALS), multiple system atrophy type P (MSA-P), multiple system atrophy type C (MSA-C), frontotemporal dementia with parkinsonism, progressive supranuclear palsy, corticobasal degeneration, Lewy Body dementia, Parkinson's Disease, and ataxia telangiectasia (Louis Barr disease).

9. A method of reversing progression of a neurodegenerative disease or one or more symptoms associated with a neurodegenerative disease over time in a subject in need thereof comprising:

administering a therapeutically effective amount of the acetyl-leucine or a pharmaceutically acceptable salt thereof to the subject for a duration chosen from at least about 3 months, at least about 6 months, at least about 1 year, at least about 2 years, and at least about 5 years,

wherein the neurodegenerative disease is not cerebellar ataxia or Niemann-Pick Type C, and

wherein the neurodegenerative disease is chosen from Alzheimer's disease, amyotrophic lateral sclerosis (ALS), multiple system atrophy type P (MSA-P), multiple system atrophy type C (MSA-C), frontotemporal dementia with parkinsonism, progressive supranuclear palsy, corticobasal degeneration, Lewy Body dementia, Parkinson's Disease, and ataxia telangiectasia (Louis Barr disease).

10. The method according to claim 1 , wherein the method comprises initiating administration of a therapeutically effective amount of acetyl-leucine or a pharmaceutically acceptable salt thereof to the subject in need thereof when the subject is asymptomatic.

11. The method according to claim 10 , wherein the initial administration occurs after the subject has been found to have a genetic and/or biochemical marker of the neurodegenerative disease.

12. The method according to claim 1 , wherein the method comprises administering a therapeutically effective amount of the acetyl-leucine or a pharmaceutically acceptable salt thereof to the subject for a duration chosen from at least about 3 months, at least about 6 months, at least about 1 year, at least about 2 years, and at least about 5 years.

13. The method according to claim 1 , wherein the acetyl-leucine is acetyl-DL-leucine.

14. The method according to claim 1 , wherein the acetyl-leucine has an enantiomeric excess of the L-enantiomer or the D-enantiomer.

15. The method according to claim 1 , wherein the therapeutically effective amount of acetyl-leucine or pharmaceutically acceptable salt thereof ranges from about 1 g to about 15 g per day, from about 1 g to about 10 g per day, from about 1.5 g to about 7 g per day, from about 4 g to about 6 g per day, or from about 4 g to about 5 g per day.

16. A method of reducing the severity of a neurodegenerative disease or reducing the severity of or eliminating one or more existing symptoms associated with a neurodegenerative disease in a subject in need thereof comprising:

administering a therapeutically effective amount of acetyl-leucine or a pharmaceutically acceptable salt thereof to the subject for a duration of at least 3 months,

wherein the neurodegenerative disease is not cerebellar ataxia or Niemann-Pick Type C,

wherein the neurodegenerative disease is chosen from Alzheimer's disease, amyotrophic lateral sclerosis (ALS), multiple system atrophy type P (MSA-P), multiple system atrophy type C (MSA-C), frontotemporal dementia with parkinsonism, progressive supranuclear palsy, corticobasal degeneration, Lewy Body dementia, Parkinson's Disease, and ataxia telangiectasia (Louis Barr disease).

17. A method of providing neuroprotection in a subject having, suspected of having, or at risk of having a neurodegenerative disease comprising:

administering a therapeutically effective amount of acetyl-leucine or a pharmaceutically acceptable salt thereof to the subject for a duration chosen from at least about 3 months, at least about 6 months, at least about 1 year, at least about 2 years, and at least about 5 years,

wherein the neurodegenerative disease is not cerebellar ataxia or Niemann-Pick Type C, and

wherein the neurodegenerative disease is chosen from Alzheimer's disease, amyotrophic lateral sclerosis (ALS), multiple system atrophy type P (MSA-P), multiple system atrophy type C (MSA-C), frontotemporal dementia with parkinsonism, progressive supranuclear palsy, corticobasal degeneration, Lewy Body dementia, Parkinson's Disease, and ataxia telangiectasia (Louis Barr disease).

18. The method according to claim 1 , wherein the acetyl-leucine is acetyl-L-leucine.