Acetyl-leucine or a pharmaceutically acceptable salt thereof for improved mobility and cognitive function

1. A method of treating a decrease in cognitive function associated with ageing in a subject in need thereof comprising:

(a) identifying the subject having the decrease in cognitive function associated with ageing;

(b) taking a baseline measurement of the subject's cognitive function using one or more tests;

(c) administering a therapeutically effective amount of acetyl-leucine or a pharmaceutically acceptable salt thereof to the subject for a treatment duration;

(d) measuring the subject's cognitive function using the one or more tests after the subject is treated; and

(e) comparing the subject's cognitive function after treatment to the baseline measurement to determine if there is an improvement in the subject's cognitive function,

wherein the subject does not have vertigo or a neurological or neurodegenerative disease, disorder, or condition.

2. The method of claim 1 , wherein the cognitive function is chosen from perception, memory, creation of imagery, awareness, reasoning, thinking and capacity for judgment.

3. The method of claim 1 , wherein the subject's cognitive function improves after treatment by at least 10% compared to the baseline measurement.

4. The method of claim 1 , wherein the acetyl-leucine is administered at least two times a day to achieve a total daily dose of from about 1.5 g to about 10 g.

5. The method of claim 1 , wherein the acetyl-leucine is administered at least two times a day to achieve a total daily dose of from about 4.5 g to about 10 g.

6. The method of claim 1 , wherein the treatment duration is at least 2 weeks, at least 7 weeks, or continuous treatment.

7. The method of claim 1 , wherein the subject is an elderly subject or a well elderly subject.

8. A method of treating a subject in need of improvement in reaction speed as a result of ageing, alertness as a result of ageing, or both reaction speed and alertness as a result of ageing comprising:

(a) identifying the subject with no apparent dysfunction in cognitive ability, movement, or balance, but in need of improvement in reaction speed, alertness, or both reaction speed and alertness, which are a direct consequence of ageing of the subject;

(b) taking a baseline measurement of the subject's reaction speed, alertness, or both reaction speed and alertness using one or more tests;

(c) administering a therapeutically effective amount of acetyl-leucine or a pharmaceutically acceptable salt thereof to the subject for a treatment duration;

(d) measuring reaction speed, alertness, or both reaction speed and alertness after the subject is treated; and

(e) comparing the subject's reaction speed, alertness, or both reaction speed and alertness after treatment compared to the baseline measurement to determine if there has been an improvement in reaction speed, alertness, or both reaction speed and alertness in the subject,

wherein the subject does not have vertigo or a neurological or neurodegenerative disease, disorder, or condition.

9. A method of treating a subject suffering from gait disorder associated with ageing, postural imbalance associated with ageing, and/or impaired spatial orientation associated with ageing in the subject comprising:

(a) identifying the subject having gait disorder, postural imbalance, and/or impaired spatial orientation associated with ageing in the subject;

(b) taking a baseline measurement of the subject's gait disorder, postural imbalance, and/or impaired spatial orientation using one or more tests;

(c) administering a therapeutically effective amount of acetyl-leucine or a pharmaceutically acceptable salt thereof to the subject for a treatment duration;

(d) measuring the subject's gait disorder, postural imbalance, and/or impaired spatial orientation after the subject is treated; and

(e) comparing the subject's gait disorder, postural imbalance, and/or impaired spatial orientation after treatment to the baseline measurement to determine if there is an improvement in the subject's gait disorder, postural imbalance, and/or impaired spatial orientation.

10. The method of claim 8 , wherein the treatment duration is at least 2 weeks, at least 7 weeks, or continuous treatment.

11. The method of claim 9 , wherein the treatment duration is at least 2 weeks, at least 7 weeks, or continuous treatment.