Methods of diagnosing or prognosing Alzheimer's disease

A method for diagnosing Alzheimer's disease in a subject, or determining whether a subject is at increased risk of developing Alzheimer's disease, comprising:

• measuring at least one of a level or biological activity of a transcription product and/or a translation product of (i) the cystatin C gene or (ii) a polymorphic variant of the cystatin C gene in at least one sample of cerebrospinal fluid from the subject;
• and
• comparing the at least one measured level or biological activity with a reference value of a corresponding control from a non-Alzheimer's-diseased individual;
• whereby, when the measured level or biological activity is elevated relative to the reference value, a diagnosis or increased risk of Alzheimer's disease in the subject is indicated.

A method of monitoring the progression of Alzheimer's disease in a subject, comprising:

• measuring at least one of a level or biological activity of a transcription product and/or a translation product of (i) the cystatin C gene or (ii) a polymorphic variant of the cystatin C gene in a series of samples of cerebrospinal fluid taken from the subject over a time period;
• and
• comparing the at least one measured level or biological activity with a reference value of a corresponding control from a non-Alzheimer's-diseased individual;
• thereby monitoring the progression of Alzheimer's disease in the subject.

A method of evaluating a treatment for Alzheimer's disease, comprising:

• measuring at least one of a level or biological activity of a transcription product and/or a translation product of (i) the cystatin C gene or (ii) a polymorphic variant of the cystatin C gene a series of samples of cerebrospinal fluid taken from the subject over a time period;
• and
• comparing the at least one measured level or biological activity with a corresponding control from a non-Alzheimer's-diseased individual;
• thereby evaluating the treatment for Alzheimer's disease.

A method of using a kit for the diagnosis or determination of increased risk of developing Alzheimer's disease, or monitoring a progression, or monitoring success or failure of a therapeutic treatment of Alzheimer's disease in a subject, the method comprising:

• measuring at least one of a level or biological activity of a transcription product and/or a translation product of (i) the cystatin C gene or (ii) a polymorphic variant of the cystatin C gene in a series of samples of cerebrospinal fluid taken from the subject over a time period;
• and
• comparing the at least one measured level or biological activity with a reference value of a corresponding control from a non-Alzheimer's-diseased individual;
• whereby, when the measured level or biological activity is elevated relative to the reference value, a diagnosis or increased risk of Alzheimer's disease in the subject is indicated, wherein the kit comprises
• a) at least one reagent selected from the group consisting of
• reagents that selectively detect a transcription product of (i) the cystatin C gene or (ii) a polymorphic variant of the cystatin C gene,
• reagents that selectively detect a translation product of (i) a cystatin C gene or (ii) a polymorphic variant of a cystatin C gene, and
• reagents that selectively detect the presence or absence of a polymorphism in the cystatin C gene;
• and
• b) instructions for performing the method.