Visuo-spatial working memory deficits in current and former users of MDMA ('ecstasy')

Verbal working memory and executive deficits have been observed in ecstasy users. The present study sought to establish whether these also extended to visuo-spatial working memory. Thirty-six current ecstasy users, 12 former users (abstinent for at least 6 months) and 31 individuals that had never used ecstasy were tested on a maintenance plus type visuo-spatial working memory task. The task required participants to recall a sequence of specially marked cells in a four-by-four matrix display while at the same time performing a concurrent visual judgement task. Both the current and former user groups registered impairments relative to nonusers. These remained significant following statistical controls for a range of potentially confounding variables including the use of various other drugs during the 3 months prior to testing. Users were unimpaired on a simple spatial span measure suggesting that the deficits observed reflected the executive aspects of the spatial working memory task. Also consistent with executive involvement, statistical controls for measures of verbal working memory performance (computation span) removed half of the ecstasy-related variance in spatial working memory. The possibility that the pattern of results obtained might reflect some general impairment in information processing efficiency is discussed.