Konstantinos (Kostas) Chiotis

I am an Assistant Professor and research group leader at Karolinska Institutet and a cognitive neurologist at Karolinska University Hospital. I combine clinical practice with research on Alzheimer’s disease and related neurodegenerative disorders, focusing on how biomarkers can explain differences between patients and improve diagnosis, prognosis and treatment.

Within the Translational Molecular Imaging – Nordberg and Chiotis Lab, my research connects molecular brain imaging, blood and cerebrospinal fluid biomarkers, clinical assessment and neuropathology. A central aim is to understand how different pathological processes contribute to cognitive impairment and disease progression.

I obtained my medical degree from the University of Patras, completed my PhD at Karolinska Institutet and trained as a neurologist at Karolinska University Hospital. From 2024 to 2025, I was a postdoctoral researcher at the Memory and Aging Center, University of California, San Francisco, working with Gil Rabinovici and Renaud La Joie on multimodal imaging and early-onset Alzheimer’s disease. I returned to Karolinska in 2025 to develop my research programme alongside my clinical practice.

My research focuses on the development, biological validation and clinical application of biomarkers for Alzheimer’s disease and related neurodegenerative disorders. By integrating PET and MRI with fluid biomarkers, cognitive assessments and neuropathology, I investigate three closely connected areas.

Astrocyte responses in neurodegeneration. I lead MAIN (Multimodal Astrocyte Imaging in Neurodegeneration), a research programme supported by the Swedish Research Council. The programme combines PET imaging targeting monoamine oxidase B (MAO-B) with fluid biomarkers, neuropathology and molecular analyses to characterise astrocyte responses in Alzheimer’s disease and frontotemporal lobar degeneration. A central goal is to establish what these biomarkers measure biologically and how they capture differences across diseases, pathological subtypes and disease stages.

Tau pathology and heterogeneity in Alzheimer’s disease. I use longitudinal amyloid and tau PET to investigate why Alzheimer’s disease differs between individuals, particularly across early- and late-onset disease and different clinical presentations. This work examines how the distribution and accumulation of tau relate to amyloid pathology, cognitive symptoms and subsequent decline, including through international collaborations within LEADS and ADNI.

Biomarkers for clinical assessment and treatment monitoring. I investigate how imaging and fluid biomarkers can improve the interpretation of cognitive impairment, identify mixed pathologies and predict clinically meaningful progression. This includes studying discordant biomarker profiles and validating findings against postmortem neuropathology. I also examine the biological and clinical effects of amyloid-targeting therapies in observational cohorts, with particular attention to early-onset Alzheimer’s disease.

I teach neurology, cognitive disorders and molecular neuroimaging at undergraduate, postgraduate and doctoral levels, including specialist training for physicians. My teaching includes lectures, case-based seminars, practical workshops and clinical supervision. I have contributed to course planning and examination within the medical programme at Karolinska Institutet, as well as the organisation and development of doctoral courses in translational molecular brain imaging.

I am the principal supervisor of one PhD student, a postdoctoral fellow and a research assistant. I supervise postdoctoral research, degree projects and international exchange students. I have organised journal clubs and neuroimaging seminars for doctoral students and postdoctoral researchers. My teaching connects biological mechanisms and critical evaluation of research with clinical reasoning and patient care.