Disturbances in brain cholesterol homeostasis may be involved in the pathogenesis of Alzheimer's disease (AD). Lipid-lowering medications could interfere with neurodegenerative processes in AD through cholesterol metabolism or other mechanisms. The investigators aim to estimate the causal effect of statins on cognitive function measured by MMSE and to identify the mediating or modifying effect of cholesterol between statins and cognitive function in patients with Alzheimer's disease.

Inclusion Criteria:

All patients with AD and mixed dementia registered in SveDem and from SCREAM.

Exclusion Criteria:

• All patients with a missing MMSE score at diagnosis date will be excluded from the analyses.
• Patients with at least one measurement of low-density lipoprotein cholesterol (LDL-C) within 1 year before dementia diagnosis.

Prospective cohort study based on data from the Stockholm Creatinine Measurements (SCREAM) project, linking laboratory data with SveDem-the Swedish Registry for Dementia Cognitive disorders, the National Patient Registry, the Swedish Prescribed Drug Registry, The Swedish Cause of Death Register and Health Insurance and Labour Market Studies (LISA). Dates between May 1, 2007, and October 16, 2018