Rumination prospectively predicts executive functioning impairments in adolescents

Background and objectives

The current study tested the resource allocation hypothesis, examining whether baseline rumination or depressive symptom levels prospectively predicted deficits in executive functioning in an adolescent sample. The alternative to this hypothesis was also evaluated by testing whether lower initial levels of executive functioning predicted increases in rumination or depressive symptoms at follow-up.

Methods

A community sample of 200 adolescents (ages 12–13) completed measures of depressive symptoms, rumination, and executive functioning at baseline and at a follow-up session approximately 15 months later.

Results

Adolescents with higher levels of baseline rumination displayed decreases in selective attention and attentional switching at follow-up. Rumination did not predict changes in working memory or sustained and divided attention. Depressive symptoms were not found to predict significant changes in executive functioning scores at follow-up. Baseline executive functioning was not associated with change in rumination or depression over time.

Conclusions

Findings partially support the resource allocation hypothesis that engaging in ruminative thoughts consumes cognitive resources that would otherwise be allocated towards difficult tests of executive functioning. Support was not found for the alternative hypothesis that lower levels of initial executive functioning would predict increased rumination or depressive symptoms at follow-up. Our study is the first to find support for the resource allocation hypothesis using a longitudinal design and an adolescent sample. Findings highlight the potentially detrimental effects of rumination on executive functioning during early adolescence.     

Cognitive functions and serum levels of brain-derived neurotrophic factor in patients with major depressive disorder

Objective

We assessed major cognitive domains in major depressive disorder (MDD) compared to a healthy control group using neurocognitive tests. We hypothesized that lower serum brain-derived neurotrophic factor (BDNF) levels would be associated with poorer neurocognitive performance in patients with major depression and that these associations would be shown in healthy controls as well.

Method

Executive functions, sustaining and focusing of attention, memory functions, and verbal fluency were assessed in this study using the Trail-Making Test (TMT), Stroop Color Word Interference Test-TBAG Form (SCWT), Wisconsin Card Sorting Test (WCST), Test of Variables of Attention (TOVA), Auditory Consonant Trigram test (ACTT), Digit Span subtest of the Wechsler Memory Scale (DST), Rey Auditory Verbal Learning Test (RAVLT), and Controlled Oral Word Association Test (COWAT).

Results

The MDD group showed significantly poorer performance than the control group in cognitive functions; they also had lower levels of BDNF than the control group. However, there was no correlation between cognitive performances and BDNF levels except in the TMT, Part B.

Conclusions

The current understanding of the importance of neurocognitive assessment and related biological markers in depression is improving. Further studies with larger sample sizes evaluating neurocognitive functions with molecular analyses of BDNF levels may reveal a novel marker for predicting and monitoring neurocognitive deficits in depression.     

Can cognitive deficits differentiate between schizophrenia with and without obsessive–compulsive symptoms?

Background

The frequent occurrence of obsessive–compulsive symptoms (OCS) in the course of schizophrenia and their impact on the functional outcome of the illness underlie the suggestion that the presence of OCS represents a separate subtype of schizophrenia, with a distinct clinical presentation and prognosis and specific neurobiological characteristics. This study investigated whether the presence of OCS in schizophrenia is associated with worse cognitive functioning in the domains of processing speed, executive functions and visuospatial memory. We also explored whether the degree of impairment in any of these cognitive domains could predict group membership (i.e. Schizophrenia with OCS [Sch-OCS] and Schizophrenia without OCS) and if there was a relationship between cognitive functioning and severity of OCS within the Sch-OCS group.

Methods

Forty patients with schizophrenia, 20 with and 20 without OCS, individually matched for age, gender, years of education and severity of psychotic symptoms and 20 healthy controls underwent a comprehensive neuropsychological assessment.

Results

Only lower performance in processing speed discriminated patients with OCS from patients without OCS. Processing speed impairment not only classified patients in OCS or non-OCS group but was also independent of the severity of OCS symptoms.

Conclusions

The notion of additive effects of both schizophrenia and OCD on the structural and functional integrity of the brain circuits that support cognitive functions warrants further investigation in longitudinal neuropsychological and neuroimaging studies with larger samples and sufficient variation in the severity of OCS.     

Deterioro cognitivo y tratamiento antirretroviral en pacientes con virus de la inmunodeficiencia humana en una población peruana

Background

HIV-associated cognitive impairment occurs even in the early stages of infection. Short-term memory, psychomotor speed, attention, and executive functioning are the main capacities affected. Controversy exists regarding whether highly active antiretroviral therapy (HAART) is helpful in combating this process. The objective of the present study is to determine the association between cognitive impairment and HAART in HIV-infected patients from Hospital Regional de Huacho.

Methods

Prospective study of HIV patients meeting criteria to start HAART. Twenty-one HIV-positive patients were recruited between April and July 2011. Researchers administered a standardised neuropsychological test battery before and 4 weeks after onset of HAART. Psychomotor speed, executive function, short term memory (visual and verbal), attention, and visuospatial performance were evaluated.

Results

Nineteen patients completed the study (14 males and 5 females). In the pre-HAART evaluation, most patients scored below average on the executive function and psychomotor speed subtests. Psychomotor speed and immediate visual memory improved significantly after four months of treatment with HAART.

Conclusions

Some degree of cognitive decline may present even in the early and asymptomatic stages of HIV infection. The benefits of antiretroviral treatment for cognitive performance can be detected after only a few weeks of follow-up.     

Cognition and communication dysfunctions in early-onset schizophrenia: Effect of risperidone

Background

Cognitive impairment and formal thought disorder, also referred to as communication disturbances, are considered the core symptoms of schizophrenia, strongly affecting social functioning and long-term outcome. Several studies in adult patients suggest improvement of both functions after the treatment with atypical antipsychotic drugs. Such medications are also used as first line treatment in early-onset schizophrenia, however their efficacy in cognitive and communication domains in this population have not been systematically assessed.

Aim of the study

Evaluation of risperidone efficacy at psychopathological symptoms, cognitive impairment and formal thought disorder in adolescents with schizophrenia spectrum diagnosis.

Material and method

Psychopathological symptoms, cognitive functioning and formal thought disorder were evaluated in 32 hospitalized adolescent patients with schizophrenia spectrum diagnosis at the beginning of risperidone treatment and after clinical improvement and compared to the results of matched healthy control group.

Results

Risperidone treatment was associated with reduction of symptom severity and moderate improvement of formal thought disorder and some aspects of executive functions. Working memory and verbal fluency were not improved. There were few correlations between psychopathological symptoms and results of cognitive tests, mainly between negative symptoms and executive functions.

Discussion

In early-onset schizophrenia spectrum disorders atypical antipsychotic treatment is associated with alleviation of symptoms and only selective and moderate cognitive and communication improvement.     

Altered neural circuits related to sustained attention and executive control in children with ADHD: An event-related fMRI study

Objective

The aim of this study was to investigate the neural basis of sustained attention, executive processing, and cognitive control in children with attention deficit hyperactivity disorder (ADHD).

Methods

Event-related functional magnetic resonance imaging (fMRI) was used to compare brain activation of 28 medication-naïve children with ADHD aged 7–12 years and 31 healthy controls during a cued continuous performance task (AX-CPT) in three stimulus context conditions (Go, NoGo, Lure).

Results

The children with ADHD showed increased activation in the left middle frontal gyrus, bilateral middle temporal gyrus, left precuneus and right cerebellum posterior lobe under the Lure condition compared to the controls. In the Lure condition, in contrast to the NoGo condition, an increased activation in the left inferior frontal gyrus, right medial frontal gyrus and right inferior parietal gyrus was observed in ADHD children.

Conclusions

The results demonstrate that medication-naïve ADHD children show spatial and temporal abnormalities in neural activities involved in sustained attention and executive control.

Significance

These findings show that there are distinct alternations in neural circuits related to sustained attention and executive control in children with ADHD, and further improve our understanding of the neural substrates of cognitive impairment in children with ADHD.     

Cognitive endophenotypes in OCD: A study of unaffected siblings of probands with familial OCD

Background

Impairments in executive functions and non-verbal memory are considered potential endophenotype markers of obsessive–compulsive disorder (OCD). For the neuropsychological deficits to be considered endophenotypes, they should be demonstrable in unaffected family members.

Aim

To compare the neuropsychological performance in unaffected siblings of probands with familial OCD with that of individually matched healthy controls.

Methods

Twenty-five unaffected siblings of OCD probands with familial OCD, and 25 individually matched healthy controls were assessed with tests of attention, executive function, memory and intelligence.

Results

Unaffected siblings showed significant deficits in tests of decision making and behavioural reversal i.e., the Iowa Gambling Task (IGT) and the Delayed Alternation Test (DAT) respectively, but performed adequately in other tests.

Conclusions

Our study suggests that the deficits in decision making and behavioural reversal could be potential endophenotypes in OCD. These deficits are consistent with the proposed neurobiological model of OCD involving the orbitofrontal cortex. Future studies could couple cognitive and imaging strategies to identify neurocognitive endophenotypes in homogenous samples of OCD.     

Generalization of cognitive training in an Australian sample of schizophrenia patients

Objective

The present study was undertaken to evaluate the effect of cognitive training in improving trained and untrained cognitive processes in schizophrenia.

Methods

A simple pre- and post experimental study with a three month follow-up was conducted to determine the efficacy of cognitive training in speed of processing and executive functions improving cognition in 22 schizophrenia patients.

Results

Significant improvement was found in those cognitive domains specifically targeted in the training protocol, but also to a limited extent on verbal memory and social cognition. There was also evidence of improvements in symptoms and social functioning. The training effects failed to transfer to community functioning skills however. Except for social cognition, these improvements were maintained at 3 month follow-up.

Conclusion

The study highlights the importance of understanding the mechanisms that contribute to the transfer of skills as well as the maintenance of cognitive changes in individuals with schizophrenia.     

The TAS-20 more likely measures negative affects rather than alexithymia itself in patients with major depression,panic disorder,eating disorders and substance use disorders

Background

This study evaluates whether the difference in Toronto Alexithymia Scale-20 item (TAS-20) between patients with major depression (MD), panic disorder (PD), eating disorders (ED), and substance use disorders (SUD) and healthy controls persisted after controlling for the severity of anxiety and depression.

Methods

Thirty-eight patients with MD, 58 with PD, 52 with ED, and 30 with SUD and 78 healthy controls (C) completed the TAS-20, the Hamilton Rating Scale for Anxiety (Ham-A), the Hamilton Rating Scale for Depression (Ham-D).

Results

The differences in TAS-20 scores observed between patient groups, regardless of the type of their disorders, and controls disappeared after controlling for the effect of anxiety and depression severity. In contrast, the differences in severity of anxiety and depression between patients and controls were still present, after excluding the effect of alexithymic levels.

Conclusions

Our data suggest that alexithymic levels, as measured by the TAS-20, are modulated by the severity of symptoms, supporting the view that alexithymia can represent a state phenomenon in patients with MD, PD, ED and SUD, because the TAS-20 seems overly sensitive to a general distress syndrome, and it is more likely to measure negative affects rather than alexithymia itself.     

Adolescent Anorexia Nervosa: Cognitive performance after weight recovery

Objective

Although there is no definitive consensus on the impairment of neuropsychological functions, most studies of adults with Anorexia Nervosa (AN) find impaired functioning in cognitive domains such as visual–spatial abilities. The objective of this study is to assess the cognitive functions in adolescents with AN before and after weight recovery and to explore the relationship between cognitive performance and menstruation.

Methods

Twenty-five female adolescents with AN were assessed by a neuropsychological battery while underweight and then following six months of treatment and weight recovery. Twenty-six healthy female subjects of a similar age were also evaluated at both time points.

Results

Underweight patients with AN showed worse cognitive performance than control subjects in immediate recall, organization and time taken to copy the Rey's Complex Figure Test (RCFT). After weight recovery, AN patients presented significant improvements in all tests, and differences between patients and controls disappeared. Patients with AN and persistence of amenorrhea at follow-up (n = 8) performed worse on Block Design, delayed recall of Visual Reproduction and Stroop Test than patients with resumed menstruation (n = 14) and the control group, though the two AN groups were similar in body mass index, age and psychopathological scale scores.

Conclusion

Weight recovery improves cognitive functioning in adolescents with AN. The normalization of neuropsychological performance is better in patients who have recovered at least one menstrual cycle. The normalization of hormonal function seems to be essential for the normalization of cognitive performance, even in adolescents with a very short recovery time.     

Underlying mechanisms of verbal memory deficits in obsessive-compulsive disorder and major depression--the role of cognitive self-consciousness

Background and Objectives

Previous studies have demonstrated that some individuals suffering from obsessive-compulsive disorder (OCD) are impaired in verbal memory performance. This study was designed to investigate the role of cognitive self-consciousness (CSC) as a putative underlying mechanism of these cognitive deficits.

Methods

Verbal memory performance of 36 participants with OCD, 36 individuals with major depression disorder (MDD) and 36 healthy controls was assessed with the California Verbal Learning Test under three different experimental conditions: (1) single-task condition, (2) while simultaneously focusing on their thoughts (CSC condition), (3) while simultaneously focusing on external stimuli (dual-task condition).

Results

Memory performance in the CSC condition and in the dual-task condition was reduced compared to single-task condition but no interaction effect was found.

Limitations

It remains unclear whether CSC and other concepts with an inward self-referential focus of attention (e.g. rumination) differ in the way they influence cognitive performance.

Conclusions

These results confirm the deteriorating influence of heightened CSC on verbal memory encoding but suggest that the effect is not specific to OCD.     

Unilateral deep brain stimulation of the nucleus accumbens in patients with treatment-resistant obsessive-compulsive disorder: Outcomes after one year

Objective

To investigate the effects of unilateral deep brain stimulation (DBS) in the right nucleus accumbens in patients with obsessive-compulsive disorder (OCD). Predominantly bilateral stimulation of the anterior limb of the internal capsule was utilized.

Methods

The study was designed as a double-blind sham-controlled crossover study. Patients received 3 months of deep brain stimulation followed by 3 months of sham stimulation, or vice versa. Subsequently, stimulation was continued unblinded for all patients. The primary outcome measure was the severity level of OCD, measured using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS). Secondary outcome measures were depressive symptoms, anxiety, psychological symptom severity, global functioning, quality of life, and cognitive function.

Results

The mean Y-BOCS scores decreased significantly from 32.2 (±4.0) at baseline to 25.4 (±6.7) after 12 months (p = 0.012). Five out of ten patients showed a decrease of more than 25%, indicating at least a partial response. One patient showed a decrease in Y-BOCS severity greater than 35%. Similarly, depression, global functioning and quality of life improved within one year. In contrast, anxiety, global symptom severity and cognitive function showed no significant changes. In general, DBS was well-tolerated.

Conclusions

DBS of the unilateral right nucleus accumbens showed encouraging results in patients with treatment-resistant OCD. Five out of ten patients reached at least a partial response after the first year.     

Subcortical brain volumes relate to neurocognition in schizophrenia and bipolar disorder and healthy controls

Background

Similar patterns of subcortical brain abnormalities and neurocognitive dysfunction have been demonstrated in schizophrenia and bipolar disorder, with more extensive findings in schizophrenia. It is unknown whether relationships between subcortical volumes and neurocognitive performance are similar or different between schizophrenia and bipolar disorder.

Methods

MRI scans and neuropsychological test performance were obtained from 117 schizophrenia or 121 bipolar spectrum disorder patients and 192 healthy control subjects. Using the FreeSurfer software, volumes of 18 selected subcortical structures were automatically segmented and analyzed for relationships with results from 7 neurocognitive tests.

Results

In schizophrenia, larger left ventricular volumes were related to poorer motor speed, and bilateral putamen volumes were related to poorer verbal learning, executive functioning and working memory performance. In bipolar disorder, larger left ventricular volumes were related to poorer motor speed and executive functioning. The relationship between left putamen volume and working memory was specific to schizophrenia. The relationships between left inferior lateral ventricles and motor speed and between right putamen volumes and executive functioning were similar in schizophrenia and bipolar disorder, and different from healthy controls. The results remained significant after corrections for use of antipsychotic medication. Significant structure-function relationships were also found when all subjects were combined into one group.

Conclusion

The present findings suggest that there are differences as well as similarities in subcortical structure/function relationships between patients with schizophrenia or bipolar disorder and healthy individuals. The observed differences further suggest that ventricular and putamen volume sizes may reflect severity of cognitive dysfunction in these disorders.     

Effects of venlafaxine and fluoxetine on lymphocyte subsets in patients with major depressive disorder: A flow cytometric analysis

Background

Studies have yielded conflicting results concerning flow cytometric lymphocyte analyses in patients with depression. Data about the effect of antidepressants on lymphocyte subsets are also contradictory. The aim of this study was to determine effects of venlafaxine versus fluoxetine on lymphocyte subsets in depressive patients.

Methods

Sixty-nine patients diagnosed with major depressive disorder (MDD) according to DSM-IV and 36 healthy controls are included in the study. Sixty-nine patients were randomized to take fluoxetine (FLX) (n = 33) or venlafaxine (VEN) (n = 36). Serum lymphocyte subsets included CD3, CD4, CD8, CD16/56, CD19, CD45, Anti-HLA-DR which were measured by flow cytometric analyses at baseline and 6 weeks after the start of treatment. The severity of depression was evaluated with Hamilton rating scale for depression.

Results

At baseline, patients with MDD had significantly lower CD16/56 ratio and higher CD45 ratio compared to the controls. Although numerically higher in the VEN treated patients, treatment response rates between the FLX (53%) and the VEN (75%) groups were not different statistically. CD45 values decreased significantly in the VEN group at the end of the 6 week treatment period whereas no difference was observed in the FLX group. By the 6th week, treatment responders showed a significantly higher CD16/56 ratio than non-responders. Baseline severity of depression and anxiety was positively correlated with baseline CD45 ratio and negatively correlated with baseline CD16/56 ratio. We did not observe consistent changes in the absolute number of circulating B or T cells, nor in the helper/inducer (CD4) or suppressor/cytotoxic (CD8) subsets.

Conclusions

CD16/56 was lower in patients with MDD and increased in treatment responders at 6th week. CD45 ratio was higher in patients with MDD than healthy subjects; it decreased with antidepressant treatment and was positively correlated with the severity of depression. Antidepressant treatment contributes to immune regulation in patients with major depressive disorder.     

Implicit and explicit self-esteem and their reciprocal relationship with symptoms of depression and social anxiety: A longitudinal study in adolescents

Background and Objectives

A negative self-view is a prominent factor in most cognitive vulnerability models of depression and anxiety. Recently, there has been increased attention to differentiate between the implicit (automatic) and the explicit (reflective) processing of self-related evaluations. This longitudinal study aimed to test the association between implicit and explicit self-esteem and symptoms of adolescent depression and social anxiety disorder. Two complementary models were tested: the vulnerability model and the scarring effect model.

Method

Participants were 1641 first and second year pupils of secondary schools in the Netherlands. The Rosenberg Self-Esteem Scale, self-esteem Implicit Association Test and Revised Child Anxiety and Depression Scale were completed to measure explicit self-esteem, implicit self-esteem and symptoms of social anxiety disorder (SAD) and major depressive disorder (MDD), respectively, at baseline and two-year follow-up.

Results

Explicit self-esteem at baseline was associated with symptoms of MDD and SAD at follow-up. Symptomatology at baseline was not associated with explicit self-esteem at follow-up. Implicit self-esteem was not associated with symptoms of MDD or SAD in either direction.

Limitations

We relied on self-report measures of MDD and SAD symptomatology. Also, findings are based on a non-clinical sample.

Conclusions

Our findings support the vulnerability model, and not the scarring effect model. The implications of these findings suggest support of an explicit self-esteem intervention to prevent increases in MDD and SAD symptomatology in non-clinical adolescents.     

Traducción al español y validación de una batería ejecutiva (BE25) y su versión abreviada (ABE12) para la detección de disfunción ejecutiva en demencias

Introduction

There is a need for clinically administered instruments capable of detecting executive dysfunction in dementia.

Objective

The translation and validation of Executive Battery 25 (EB25) and a short version for screening of executive dysfunction in dementia. Methods: The original battery was translated and validated using convergent and divergent correlation in 66 mild dementia patients (CDR 1) matched with 66 controls. EB25 consists of 25 items which detect executive dysfunction. Convergent correlation was made with 7 tests assessing executive dysfunction, the Frontal Systems Behaviour Scale (FrSBe) and Disability Fast Assessment Scale.

Results

Patients had higher scores than controls and correlated with the Stroop Test, verbal fluency test and Frontal Behaviour Inventory. Only 12 out of 25 items were needed to separate both groups, which were used to build an abbreviated Executive Battery with equal psychometric properties and discriminative power. The cut-off point for EB25 was 12, and 7 for the abbreviated version. A cut-off point of 12 was able to discriminate between ¿Alzheimer's disease? (AD) and frontotemporal lobe dementia (FTLD).

Conclusions

EB25 and AEB12 enable executive dysfunction to be detected in mild dementia. On the other hand, AEB12 exhibits better psychometric properties than the original battery, allowing discrimination between AD and FTLD and is completed in less time.     

Cognitive vulnerability to comorbidity: looming cognitive style and depressive cognitive style as synergistic predictors of anxiety and depression symptoms

Background and objectives

Because anxiety and depression are highly comorbid, it is likely that individuals with co-occurring cognitive vulnerabilities to depression and anxiety will experience more severe symptoms of anxiety and depression. However, no study to date has examined the effects of co-occurring (simultaneous) cognitive vulnerabilities to depression and anxiety on the severity of symptoms.

Method

The present study examines the co-occurring effects of Alloy and Abramson’s (1999) Negative Cognitive Style, a vulnerability to depression, and Riskind’s (2000) looming cognitive style, a vulnerability to anxiety.

Results

Results indicated that those with co-occurring vulnerabilities experience a more severe level of anxiety and depression symptoms.

Limitations

The present study used a measure of symptoms rather than actual clinical diagnoses.

Conclusion

These findings address the previously ignored area of cognitive vulnerability to comorbidity. Co-occurring cognitive vulnerabilities to anxiety and depression synergistically confer risk for more severe anxiety and depression symptoms than the individual or additive effects of either vulnerability do alone.     

Turning the pink cloud grey: Dampening of positive affect predicts postpartum depressive symptoms

Objective

Maladaptive response styles to negative affect have been shown to be associated with prospective (postpartum) depression. Whether maladaptive styles to positive affect are also critically involved is understudied, even though anhedonia (a correlate of low positive affectivity) is a cardinal symptom of depression. The present study is the first to investigate the predictive value of cognitive response styles to both negative (depressive rumination) and positive affect (dampening) for postpartum depressive symptoms.

Methods

During the third trimester of pregnancy, 210 women completed self-report instruments assessing depression (symptom severity and current and/or past episodes) and scales gauging the presence of depressive rumination and dampening. Of these women, 187 were retained for postpartum follow-up, with depressive symptoms being reassessed at 12 (n = 171) and 24 (n = 176) weeks after delivery.

Results

Regression analyses showed that higher levels of dampening of positive affect during pregnancy predicted higher levels of depressive symptoms at 12 and 24 weeks postpartum, irrespective of initial symptom severity, past history of depression and levels of rumination to negative affect. Prepartum trait levels of rumination, however, did not predict postpartum symptomatology when controlled for baseline symptoms and history of major depressive episode(s).

Conclusions

The results of this investigation suggest that the way women cognitively respond to positive affect contributes perhaps even more to the development of postpartum depression than maladaptive response styles to negative affect.     

Depression and cognitive deficits in geriatric schizophrenia

Objective

Past reports have found patients with comorbid depression and schizophrenia spectrum disorders exhibit greater deficits in memory and attention compared to schizophrenia spectrum disorder patients without depressive symptoms. However, in contrast to younger schizophrenia patients, the few past studies using cognitive screens to examine the relationship between depression and cognition in inpatient geriatric schizophrenia have found that depressive symptomatology was associated with relatively enhanced cognitive performance. In the current study we examined the relationship between depressive symptoms and cognitive deficits in geriatric schizophrenia spectrum disorder patients (n = 71; mean age = 63.7) on an acute psychiatric inpatient service.

Method

Patients completed a battery of cognitive tests assessing memory, attention and global cognition. Symptom severity was assessed via the PANSS and Calgary Depression Scale for Schizophrenia.

Results

Results revealed that geriatric patients' depression severity predicted enhancement of their attentional and verbal memory performance. Patients' global cognitive functioning and adaptive functioning were not associated with their depression severity.

Conclusion

Contrary to patterns typically seen in younger patients and non-patient groups, increasing depression severity is associated with enhancement of memory and attention in geriatric schizophrenia spectrum disorder patients. Also, diverging from younger samples, depression severity was unassociated with patients adaptive and global cognitive functioning.     

Impact of peripheral levels of chemokines,BDNF and oxidative markers on cognition in individuals with schizophrenia

Objective

To investigate possible differences in peripheral levels of chemokines, BDNF and oxidative markers between patients with Schizophrenia (SZ) and matched healthy controls, and investigate the correlation of these biomarkers with cognitive performance.

Methods

Thirty individuals with SZ and 27 healthy controls were included and the following plasmatic biomarkers' levels were determined according to manufacturers' instructions: BDNF, TBARS, protein carbonyl content (PCC) and the chemokines CXCL-10/IP-10, CXCL-8/IL-8, CCL-11, CCL-24/Eotaxin-2, CCL-2/MCP-1, CCL-3/MIP-1. Selected neuropsychological tasks were administered to assess verbal learning (Hopkins Verbal Learning Test), verbal fluency (FAS test), working memory (Visual Working Memory Task, Keep Track Task, Letter Memory Task), set shifting (Plus–minus task, Number–letter task), inhibition (Computerized Stroop Task, Semantic Generation Task) and complex executive function tasks (Tower of London and the shortened version of the WCST-64).

Results

Compared with the healthy control group, individuals with SZ presented significantly higher levels of BDNF and the chemokine CCL-11, and lower levels of TBARS and the chemokine CXCL-10/IP-10. When we examined only the SZ group, BDNF levels were positively correlated with semantic generation tasks. Working memory ability was negatively correlated with PCC. Regarding chemokines, CCL-11 was negatively correlated to performance in working memory test, and positively correlated with cognitive flexibility task. CXCL-8/IL-8 was positively correlated with verbal fluency. CCL-24/Eotaxin-2 was positively correlated with semantic generation ability and letter memory task.

Conclusions

Our results indicate that cognitive performance in SZ is associated with mediators of neuroplasticity that can be measured peripherally.