PTGDS and Alzheimer disease: Additionally, lipocalin-type prostaglandin D synthase (PGDS), also known as b-trace protein, considered to be mainly produced in the leptomeninges playing a role in prostaglandin metabolism and in retinoids’ transfer, has been found to have significantly lower concentration in CSF of NPH patients than in patients with other causes of dementia, such as AD, patients with depression and healthy individuals [67,68].