The present invention addresses the problem of providing an agent for preventing or treating
amyotrophic lateral sclerosis (ALS), Parkinson's
disease (PD), Huntington's
disease (HD),
spinocerebellar ataxia (SCA), aging-related degenerative or neurological
disease,
brain aging, or diseases associated with
brain aging, as well as a more stable
antibody that exhibits an effect of preventing or treating these diseases, Alzheimer's disease (AD), or frontotemporal lobar degeneration (FTLD). A human
monoclonal antibody that specifically binds to human HMGB1, wherein the human
monoclonal antibody (anti-human HMGB1 antibody) comprises a
heavy chain CDR1,
heavy chain CDR2, and
heavy chain CDR3 each consisting of a specific
amino acid sequence and a light chain CDR1, light chain CDR2, and light chain CDR3 each consisting of a specific
amino acid sequence, is used as an agent for preventing or treating ALS, PD, HD, SCA, aging-related degenerative or neurological disease,
brain aging, or diseases associated with brain aging. An antibody in which the light chain
complementarity determining region (CDR) 3 of the anti-human HMGB1 antibody has been modified is used.