Ida Karlsson

I am Assistant professor and Docent in epidemiology, and lead the research group Epidemiology of cardiometabolic and cognitive aging. My main interest is combining genetic and longitudinal designs to understand complex aging-related traits. My research centers on two themes: 1) understanding how obesity influences late-life health, viewing obesity as a complex and heterogeneous condition with different causes and consequences, and 2) how long-term genetic, biological, and lifestyle factors shape risk and resilience to dementia.

Adiposity and the risk of age-related disease
The project aims to leverage the heterogeneity of adiposity-related traits to understand when, how, and for whom obesity matters for late-life health. My hypothesis is that specific adiposity-related traits have different effects on the risk of age-related diseases, and that these differences are explained by e.g. metabolic factors or accelerated aging. I study adiposity in general (e.g. BMI and body fat distribution), and specific adiposity-related traits: a) metabolically unhealthy vs healthy adiposity, b) environmentally vs genetically driven adiposity, and c) adiposity measured in midlife vs late-life. These adiposity-related traits are associated with substantially increased, vs only slightly increased or even decreased risk of age-related disease (compared to having a normal weight), and by studying what differs between them, I aim to advance our understanding of both the heterogeneity of obesity and of how adiposity in general affects late-life health.

Life-course risk factors and blood‑based biomarkers for dementia

This project focuses on understanding how genetic, biological, and modifiable life‑course factors jointly shape risk and resilience to dementia and cognitive decline. The work builds on large, harmonized twin resources, including the Swedish Adoption/Twin Study of Aging (SATSA) and other studies in the Interplay of Genes and Environment across Multiple Studies (IGEMS) consortium. A major focus is the use of blood‑based biomarkers to study the long preclinical phase of dementia in population‑based and genetically informative cohorts. Recent advances in plasma markers of Alzheimer’s disease pathology enable investigation of preclinical disease processes, decades before clinical symptoms, overcoming key limitations of symptom‑based research. By combining repeated biomarker measurements with twin designs, multi‑omics data, and long-term cognitive follow‑up, my research aims to disentangle causal risk factors from genetic and familial confounding, identify early biological pathways leading to dementia, and develop interpretable models for individualized risk prediction and stratification of preclinical disease.

Course director:

• An introduction to genetic and molecular epidemiology, Karolinska Institutet, from 2021 (PhD course, 1.5 credits)
• Statistical Methods, School of Health and Welfare, Jönköping University, 2020 (PhD course, 7.5 credits)

Lecturer:
Karolinska Institutet, from 2021:

• Lectures on genetic epidemiology, cognition, and dementia (bachelor and master level)
• Leader of seminars, group work, laboratory assignments in epidemiology and biostatistics

School of Health and Welfare, Jönköping University, 2018-2020:

• Lectures on statistical methods (doctoral level)
• Lectures on cognition and dementia (bachelor and master level)

Supervision/mentoring:

• Elsa Ojalehto, PhD student
• Emilija Romic (as co-supervisor), PhD student at Umeå University
• Manasa Shanta Näsholm (as co-supervisor), MSCA Postdoctoral researcher at KI, Department of Neurobiology, Care Sciences and Society
• Martin Nakash, research assistant (amanuens)
• Otto-Emil Jutila (as co-supervisor), PhD student at the University of Edinburgh, Precision Medicine Doctoral Training Program
• Yuling Yu, Postdoctoral researcher 

Former students:

• Peggy Ler, PhD student at Karolinska Institutet, Department of Medical Epidemiology and Biostatistics, graduation November 2024. Thesis: Disentangling the body bass index, metabolic health and aging connection: weighty matters
• Anita Paul, master student from Stockholm University, Public health department, VT 2022
• Axel Ryding, medical degree student at Karolinska Institutet, HT 2023; research assistant (amanuens), September 2024 - June 2025
• Martin Nakash, medical degree student at Karolinska Institutet, VT 2024; research assistant (amanuens), September 2024 - January 2026