Working memory and attention deficits in adolescent offspring of schizophrenia or bipolar patients: comparing vulnerability markers

Abstract

Background: Working memory deficits abound in schizophrenia and attention deficits have been documented in schizophrenia and bipolar disorder. Adolescent offspring of patients may inherit vulnerabilities in brain circuits that subserve these cognitive domains. Here we assess impairments in offspring of schizophrenia (SCZ-Offspring) or bipolar (BP-Offspring) patients compared to controls (HC) with no family history of mood or psychotic disorders to the second degree.

Methods: Three groups (n=100 subjects; range: 10-20 yrs) of HC, SCZ-Offspring and BP-Offspring gave informed consent. Working memory was assessed using a delayed spatial memory paradigm with two levels of delay (2s & 12s); sustained attention processing was assessed using the Continuous Performance Task-Identical Pairs version.

Results: SCZ-Offspring (but not BP-Offspring) showed impairments in working memory (relative to HC) at the longer memory delay indicating a unique deficit. Both groups showed reduced sensitivity during attention but only BP-Offspring significantly differed from controls.

Conclusions: These results suggest unique (working memory/dorsal frontal cortex) and potentially overlapping (attention/fronto-striatal cortex) vulnerability pathways in adolescent offspring of patients with schizophrenia and bipolar disorder. Working memory and attention assessments in these offspring may assist in the clinical characterization of the adolescents vulnerable to SCZ or BP.

Figure 1

(a) Group and age-related differences in spatial working memory (2s and 12 s delay) are depicted. As seen, impairment in SCZ-Offspring is evident at the longer delay interval where SCZ-Offspring differed from both HC and BP-Offpsring. Error bars are ± s.e.m. (b) Working memory decreases with age across groups are evident at the 12 s delay. A single regression function (with mean confidence interval) collapsing across groups was significant, F_1,90=7.01, p<.01, β=−.27. (c) By comparison, at the easier level of memory, age-related effects were weaker, (F_1,90=4.35, p<.05, β=−.2).

Figure 2

Reductions in sensitivity during sustained attention are depicted in SCZ-Offspring and BP-Offspring relative to HC. A main effect of group was primarily driven by differences between BP-Offspring and HC (see Results). Error bars are ± s.e.m..