Simple blood test could spot Alzheimer's early

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: General (all groups): * Male or female participants aged 50 to 85 years. * Signed and dated written informed consent (or consent from a legally authorized representative when applicable). Alzheimer's Disease (AD) Group: * Clinical diagnosis of Alzheimer's disease with a gradual and progressive decline in memory over at least 6 months. * Objective evidence of an amnestic syndrome of the hippocampal type (based on RLRI-16, MoCA, or equivalent tests). * Montreal Cognitive Assessment (MoCA) score between 15 and 23 (inclusive). * Structural MRI compatible with a typical AD diagnosis (3D volumetric MRI required; amyloid PET if available). * Retrospective CSF biomarker results showing at least 2 of 3 markers positive (Aβ1-42, total Tau, phosphorylated Tau). * Patients with familial AD forms (mutations in APP, PSEN1, or PSEN2) may also be included. Non-Alzheimer Neurodegenerative Disease (NAD) Group: * 25 patients with frontotemporal dementia (FTD) and 25 patients with Parkinson's disease (PD) responsive to L-DOPA. * Retrospective CSF biomarker results showing negative or non-AD profiles (≥2 of 3 markers negative). * Neuroimaging compatible with respective diagnoses: FTD: medial temporal atrophy and frontal atrophy score ≥2; MoCA 15-23. PD: evidence of dopaminergic neuron loss in substantia nigra; MoCA \>23. Healthy Control (HC) Group: * Normal cognitive status (MoCA \>23 and normal performance on RLRI-16 or equivalent neuropsychological tests). * Normal structural MRI (and normal PET scan, if available). * Negative CSF biomarkers (if available). Exclusion Criteria: General (all groups): * Neutropenia (neutrophils \<1,500/mm³) or thrombocytopenia (platelets \<100,000/mm³). * Education level below primary school. * History of psychiatric disorders (schizophrenia, psychosis). * Vascular dementia or mixed dementia. * Active infectious or chronic inflammatory diseases affecting blood cell function. * Active cancer or cancer under treatment, or treatment stopped within the last 3 months. * Use of medications interfering with cognitive function or biomarkers of interest. * Major sensory deficits (visual or auditory) affecting cognitive testing. * Epilepsy. * Known contraindication to MRI (e.g., stent or metallic implant). Group-specific exclusions: * AD group: Exclude vascular dementia, Lewy body dementia, mixed dementia, or any non-AD neurodegenerative disease. * NAD group: Exclude Alzheimer's disease, vascular, or mixed dementia. * HC group: Exclude any neurodegenerative disease, cognitive disorder, or abnormal cognitive testing.