Increased reflection impulsivity in patients with ephedrone-induced Parkinsonism
Correspondence to: Bruno B. Averbeck, Laboratory of Neuropsychology, NIMH/NIH, Building 49 Room 1B80, 49 Convent Drive MSC 4415, Bethesda, MD 20892-4415, USA. E-mail: firstname.lastname@example.org. Andrew J. Lees, Reta Lila Weston Institute of Neurological Studies, UCL Institute of Neurology, 1 Wakefield Street, London WC1N 1PJ, UK. E-mail: email@example.com
To examine a syndrome of chronic manganism that occurs in drug addicts in eastern Europe who use intravenous methcathinone (ephedrone) contaminated with potassium permanganate. In many cases the basal ganglia, especially the globus pallidus and the putamen, are damaged irreversibly. Routine neuropsychological assessment has revealed no cognitive deficits, despite widespread abnormalities on brain imaging studies and severe extrapyramidal motor handicap on clinical examination.
Ephedrone patients and patients with opioid dependence were recruited from Lviv, Ukraine.
We tested 15 patients with ephedrone-induced toxicity, 13 opiate-dependent patients who were receiving opioid replacement therapy and 18 matched healthy volunteers.
The ‘beads task’, an information-gathering task to assess reflection impulsivity, was used and feedback learning, working memory and risk-taking were also assessed.
Opiate-dependent patients differed from controls on three of four tasks, whereas ephedrone patients differed from controls on only one task. More specifically, both patient groups were more impulsive and made more irrational choices on the beads task than controls (P < 0.001). However, ephedrone patients had no deficits in working memory (P > 0.1) or risk-taking (P > 0.1) compared with controls. Opioid-dependent patients had significantly worse working memory (P < 0.001) and were significantly more risk-prone than controls (P = 0.002).
Ephedrone patients may have similar deficits in information-gathering and decision-making to opiate-dependent patients, with preservation of working memory and risk-taking. This may reflect specific damage to anterior cingulate– basal ganglia loops.