Dementia with Lewy bodies is often hard to diagnose because its early symptoms may resemble those of Alzheimer’s or a psychiatric illness. The good news is that doctors are increasingly able to diagnose Lewy body dementia earlier and more accurately as researchers identify which symptoms and biomarkers (biological signs of disease) help distinguish it from similar disorders.
Clinicians and researchers use the “1-year rule” to help make a diagnosis based on the timing of symptoms, such that:
- If cognitive symptoms appear at the same time as or at least one year before movement problems, the diagnosis is dementia with Lewy bodies.
- If cognitive problems develop more than one year after the onset of movement problems, the diagnosis is Parkinson’s disease dementia.
Learn more about diagnosing Lewy body dementia on NIA’s website.