Semantic memory impairments are a common symptom of Alzheimer's disease (AD) and may occur at a relatively early stage. These disturbances can be evidenced by a hyperpriming effect (greater semantic priming in AD patients than in controls). Up till now, very few studies of semantic memory have included emotionally charged concepts. Our aim was therefore to study the semantic processing of such concepts, as opposed to neutral ones, in early AD. Given that emotional processes are relatively preserved at the beginning of the disease compared with other cognitive functions, we expected that an emotional connotation would influence the spreading activation of words and affect some of the impairments in semantic processing. We administered a semantic priming task (lexical decision task) implicitly assessing semantic memory to 26 patients with AD and 26 normal controls. Primes and targets either had a semantic relationship (e.g. tiger-lion), a semantic and emotional (positive or negative) relationship (e.g. slap-smack) or no relationship at all (e.g. chair-horse), or else belonged to a word-nonword condition (e.g. window-inuly). Compared with controls, the patients showed pathological hyperpriming effects in all conditions, especially in the emotional conditions. Hyperpriming implies a deterioration in specific attributes, as it is difficult to tell two concepts apart once their distinctive attributes have been lost. These results suggest that emotional concepts, like neutral ones, lose some of their distinctive attributes in early AD, and as the emotional processes are preserved, there is greater similarity between close emotional concepts than between close neutral concepts.