Long-term skill proceduralization in schizophrenia

Abstract

Previous studies had revealed no specific effect under haloperidol (typical) and risperidone (atypical) neuroleptic (NLP) treatments for schizophrenia (SZ) on a variety of neurocognitive functions relying on the dopaminergic meso-cortico-limbic system (Rémillard et al., 2005, 2008). Considering the different affinities of D2 dopamine receptors for typical and atypical NLPs, these drugs may differentially affect the functions of the striatum, a determinant brain structure involved in procedural learning. The influence of risperidone (2-6 mg) and haloperidol (2-40 mg) on a nonmotor procedural task involving semantically related pairs of words with inverted letters was investigated in this double-blind study. The performance of 26 patients with SZ, randomly assigned to risperidone or haloperidol, was compared to that of 18 healthy controls at baseline, 3, 6, and 12 months. Results revealed that all patients with SZ exhibited slower reading speed of the word pairs than healthy controls at all assessment periods. In addition, procedural learning - characterized as a significant decrease in the time taken to read aloud the target word pairs - was more impaired in the haloperidol- than in the risperidone-treated group at all assessment periods. Healthy controls showed steady improvement in reading speed over the 12 months of the study, in contrast to SZ patients, who reached a plateau in their capacity to improve mirror-reading skill over time. However, all SZ participants in the study showed near normal learning profiles from exposure to semantic associations embedded in the procedural memory task, providing evidence for the preservation of associative connections in the semantic network of these patients. The observed impairment in procedural learning in SZ may thus reflect, at least in part, the influence of neuroleptic medication on striatal functions.

Probabilistic classification and gambling in patients with schizophrenia receiving medication: comparison of risperidone, olanzapine, clozapine and typical antipsychotics

“…In a prospective study, Harris et al (2009) found that first-episode drug-naïve patients subsequently treated with risperidone became impaired on a predictive saccade task. Recently, Rémillard et al (2010) reported that risperidone does not impair the same procedural learning tasks as typical antipsychotics. Patients randomly assigned to either haloperidol or risperidone performed a task involving semantically related inverted word pairs, with the haloperidol group having greater impairment than the risperidone group at all assessment periods showing that the two drugs are not identical in their effects on this task.…”

More than just tapping: Index finger-tapping measures procedural learning in schizophrenia

“…Other tests applied to assess procedural learning in schizophrenia include the Tower of Toronto (Bedard et al, 2000; Purdon et al, 2003), Tower of Hanoï (Goldberg et al, 1990), mirror drawing tasks (Bedard et al, 1996a; Bedard et al, 2000; Paquet et al, 2004; Scherer et al, 2004), serial reaction time tasks (Harris et al, 2009; Kern et al, 1998; Siegert et al, 2008), periodic sequence learning tasks (Kumari et al, 2002), rotary pursuit (Kern et al, 1998; B.L. Schwartz et al, 1996), computed visual tracking tasks (Paquet et al, 2004) and non-motor (verbal) procedural learning tests (Remillard et al, 2010). The results from these studies suggest that patients with schizophrenia demonstrate procedural learning, but that their learning profile may be impaired compared to healthy controls, potentially due to medication (Bedard et al, 2000; Kumari et al, 2002; Purdon et al, 2003; Purdon et al, 2002; Remillard et al, 2010; Stip, 2006).…”

“…Schwartz et al, 1996), computed visual tracking tasks (Paquet et al, 2004) and non-motor (verbal) procedural learning tests (Remillard et al, 2010). The results from these studies suggest that patients with schizophrenia demonstrate procedural learning, but that their learning profile may be impaired compared to healthy controls, potentially due to medication (Bedard et al, 2000; Kumari et al, 2002; Purdon et al, 2003; Purdon et al, 2002; Remillard et al, 2010; Stip, 2006). …”

“…Medication effects on procedural learning have been attributed mainly to the antagonist activity of high affinity D 2 receptor antipsychotics on dopaminergic dorsal striatum pathways (Bedard et al, 1996a; Bedard et al, 2000; Harris et al, 2009; Paquet et al, 2004; Purdon et al, 2003; Purdon et al, 2002; Remillard et al, 2010; Zedkova et al, 2006). This has also been supported by a double-blind study with healthy participants who showed improvement in procedural learning following administration of a dopamine agonist and no significant procedural learning for the group given a dopamine antagonist (Kumari et al, 1997).…”