The presence of Lewy body (LB) pathology in addition to Alzheimer disease (AD) pathology is associated with acceleration of AD-related disease progression, according to new research. In a study involving 795 participants with mild cognitive impairment or dementia, individuals with AD+LB+ biomarker profiles in their cerebrospinal fluid showed more rapid cognitive decline and greater cortical hypometabolism than those with AD+LB–, AD–LB+ or AD–LB– profiles. The findings suggest that the detection of LB pathology could have prognostic value in patients with AD.