A conjugate consisting of an insulin-like growth factor-1 (IGF-I) variant and one or two poly(ethylene glycol) group(s), characterized in that said IGF-I variant has an amino acid alteration at up to three amino acid positions 27, 37, 65, 68 of the wild-type IGF-I amino acid sequence so that one or two of said amino acids is/are lysine and amino acid 27 is a polar amino acid but not lysine, is conjugated via the primary amino group(s) of said lysine(s) and said poly(ethylene glycol) group(s) have an overall molecular weight of from 20 to 100 kDa is disclosed. This conjugate is useful for the treatment of neurodegenerative disorders like Alzheimer's Disease.