To investigate the potential improvement in cognitive levels in elderly individuals following hematopoietic stem cell transplantation, which will help better understand the changes in cognitive levels after transplantation in elderly patients, providing crucial reference for future clinical practice and research.

To investigate the potential improvement in cognitive levels in elderly individuals following hematopoietic stem cell transplantation, which will help better understand the changes in cognitive levels after transplantation in elderly patients, providing crucial reference for future clinical practice and research.

To observe changes in cognitive levels in patients aged ≥55 years receiving allogeneic hematopoietic stem cell transplantation (allo-HSCT) before and after allo-HSCT.

Inclusion Criteria:

1. Age greater than or equal to 55 years;
2. Patients planning to undergo allogeneic hematopoietic stem cell transplantation.

Exclusion Criteria:

1. Patients with active diseases;
2. Presence of central nervous system tumor invasion;
3. Planning to undergo two or more transplantations;
4. Severe cognitive impairments or mental illnesses;
5. Inability to communicate in Mandarin.

Age greater than or equal to 55 years; Patients planning to undergo allogeneic hematopoietic stem cell transplantation.