Rare diseases · Sign or symptom
Increased theta frequency activity in EEG
HP:0031535
What it means
Increased frequency of theta wave activity in the electroencephalogram. Theta waves have a frequency of 3.5-7.5 Hertz, and are present in very small amounts in healthy waking adult EEGs. Theta activity is normal in small very amounts in the healthy waking adult EEG in a symmetrical distribution.
Rare diseases that can present with this4
Sometimes5–29%
3The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Tracking symptoms like this for someone? Eleplan keeps symptoms, diagnoses, medications and every specialist in one plan.
Start free with EleplanThis page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.