Memory and Schizophrenia

It is generally accepted within the clinical and research community that cognitive dysfunctions represent a core feature of schizophrenia. Although neuropsychological studies in schizophrenia patients have repeatedly shown that multiple domains of cognition are affected, episodic memory measures consistently show the largest effect size, that is, the greatest disparity in performance between control and patient groups.1-3 Many patients exhibit episodic memory dysfunctions prior to the manifestation of clinical symptoms.4 Memory deficits are observed in young, medication-naive patients5'6 and remain stable over time.7 Disturbances in memory can also be seen in healthy first-degree relatives of patients with schizophrenia, who have never been exposed to treatment.8-10 In the last 2 decades, many researchers have come to the conclusion that episodic memory impairment indeed represents a core feature of schizophrenia,11,13 and since then, memory research in schizophrenia has been an expanding field of investigation. There is increased understanding of the conditions under which memory is more impaired,14 the association (or lack of association) with clinical symptoms has been repeatedly examined,11,15,16 and several recent functional neuroimaging studies17,23 have provided important information as to the neural correlates of these memory impairments. The 2 papers of this issue's In Review section examine separate but complementary aspects of memory problems in schizophrenia. Dr Jean-Marie Danion and his collaborators24 provide a scholarly review of experimental studies on memory impairments and schizophrenia. They show how theoretical models of episodic memory have significantly contributed to a better understanding of the memory processes selectively affected in schizophrenia and conclude that a better comprehension of those selective memory problems may guide future cognitive remediation efforts. In the second paper of this series,25 my colleagues and I review the literature on the effects of psychotic symptoms and negative symptoms (in particular, flat affect and anhedonia) on memory bias in schizophrenia patients. Memory bias refers to the modulatory influence that state or trait psychopathology may exert on memory performance for specific categories of stimuli, often emotional in nature. We argue that the exploration of such memory biases may provide fresh insights into the relation between memory functions and the symptoms of schizophrenia. Together, these 2 papers provide a good overview of the experimental and cognitively oriented work on memory in schizophrenia sufferers. The underlying framework of both our review and that of Dr Danion and colleagues is that episodic memory is not a simple construct but, instead, encompasses multiple cognitive processes. Although our understanding of memory function and dysfunction has greatly improved over the last 40 years or so, there are still many unanswered questions. As these 2 reviews clearly suggest, future studies on memory and schizophrenia will greatly benefit from developments in the field of cognitive psychology and cognitive neuroscience. We hope that these review papers may generate new research questions that will ultimately lead to a better understanding of this complex relation between memory functions and schizophrenia. [Sidebar] (Can J Psychiatry 2007;52:691-692) [Reference] References 1. Gold JM, Harvey PD. Cognitive deficits in schizophrenia. Psychiatr Clin North Am. 1993;16:295-312. 2. Saykin AJ, Gur RC, Gur RE, et al. Neuropsychological function in schizophrenia. Selective impairment in memory and learning. Arch Gen Psychiatry. 1991;48(7):618-624. 3. Heinrichs RW, Zakzanis KK. Neurocognitive deficit in schizophrenia: a quantitative review of the evidence. Neuropsychology. 1998;12(3):426-445. 4. Jones P, Rodgers B, Murray R, et al. …

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