Blood-brain Barrier Permeability in Alzheimer's Disease

Inclusion Criteria: Patients with AD: * Informed consent before participation in the study * Received standard diagnostic procedure according to the Parelsnoer Initiative procedure * Diagnosed with dementia of the Alzheimer's type * Clinical dementia rating (CDR) of 1, which means a mild to moderate stage of dementia * MMSE ≥ 20 and patients are mentally competent (in general, individuals with an MMSE ≥ 18 are considered mentally competent) Patients with prodromal AD: * Informed consent before participation in the study * Received standard diagnostic procedure according to the Parelsnoer Initiative procedure * Diagnosis of prodromal dementia according to the Dubois criteria (16) * CDR of 0.5, which suggests a very mild stage of dementia * Memory impairment defined as Delayed Recall on Verbal Learning Test (15 WLT) \< 1.5 SD * MMSE ≥ 20 and patients are mentally competent. * Medial temporal lobe atrophy scale MTA ≥ 1 (17) OR abnormal levels of Aß42, t-tau or p-tau Healthy participants: * Informed consent before participation in the study * No Diagnosis of dementia, prodromal dementia, or mild cognitive impairment. * MMSE ≥ 26 * No substantial memory complaints (according to participant) * Age, gender and education is matched to the patient groups. Exclusion Criteria: * Contraindications for scanning (e.g. brain surgery, cardiac pacemaker, metal implants, claustrophobia, large body tattoos) * Contraindications for contrast agent Gadovist (renal failure) as determined by the estimated Glomular Filtration Rate eGFR \< 30 mL/min. * Major vascular disorders (e.g. stroke, heart disease) * Psychiatric or neurological disorders: Major depression (\< 12 months); history of schizophrenia; bipolar disorder; psychotic disorder NOS or treatment for a psychotic disorder (\< 12 mnd); cognitive impairment due to alcohol abuse; epilepsy; Parkinson's disease; MS; brain surgery; brain trauma; electroshock therapy; kidney dialysis; Meniere's disease; and brain infections. * Structural abnormalities of the brain * Cognitive impairment due to alcohol/drug abuse * Absence of reliable informant (for patient groups)