This study aims to investigate whether biomarkers of Alzheimer's disease can be found in tearfluid, as well as dried bloodspots in patients with Alzheimer's disease, other dementia diagnoses compared to controls.

Participants under investigation of a neurodegenerative disease who have a planned lumbar puncture in the Memory clinic will be invited to this study. On the same day of the lumbar puncture, tear fluid and dry blod spots will be collected.

Tear fluid is collected using Shirmer's test. Dried blood spots are obtained by a small prick in the finger with a lancet. The blood droplet is transferred onto a special piece of filter paper, where it dries.

As a sub-study, participants who have provided written consent specifically for this purpose will repeat the test with dried blood spots at home one week after participating in the study. The samples are submitted to the Memory Clinic at the participant's next scheduled appointment.

Tear fluid, dried blood spots, as well as blood and cerebrospinal fluid will be examined for AD-related pathology.

Inclusion Criteria:

Inclusion criteria for patients:

• Lumbar puncture with CSF avaiable for analysis
• Diagnosis of Alzheimer's disease, Dementia with Lewy Bodies (DLB), Frontotemporal dementia (FTD), vascular dementia (VaD) or Normal pressure hydrocephalus (NPH)
• Of legal age.

Inclusion criteria for controls:

• Lumbar puncture with CSF avaiable for analysis
• No neurological disease.
• Of legal age.

Exclusion Criteria:

• No lumbar puncture
• Clinically assessed as unfit to participate in the project.

We aim to include 177 participants in each group. The diagnoses are based on internationally recognised diagnostic criteria for the individual diseases, and the diagnosis is made at a consensus conference by experienced specialists in the field of dementia.