Dimensions of executive functioning in schizophrenia and their relationship with processing speed

Context: The nature of executive dysfunction in schizophrenia is nebulous, due to inconsistencies in conceptualizing and operationalizing the construct, and the broader question of whether schizophrenia is best characterized in terms of specific vs generalized cognitive deficits. The current study aimed to determine whether executive functions represent unitary vs diverse constructs in schizophrenia.Methods: Participants included 145 community-dwelling individuals with schizophrenia. Executive functions were measured with the Delis-Kaplan Executive Functioning System (D-KEFS). We conducted an exploratory factor analysis (EFA) with principal axis factoring, as well as parallel analyses to examine the latent constructs underlying the D-KEFS tasks, a second EFA on weighted residuals of the D-KEFS tasks (after accounting for processing speed measured with the Digit Symbol task), and bivariate correlations to examine relationships between the D-KEFS components and relevant demographic and clinical variables, crystallized verbal knowledge, and functional capacity.Results: EFA of the D-KEFS tasks yielded 2 factors (cognitive flexibility/timed tests and abstraction). EFA of the processing speed-weighted D-KEFS residuals also yielded 2 factors (cognitive flexibility and abstraction). Cognitive flexibility was negatively correlated with psychopathology. Better abstraction was associated with higher education, shorter illness duration, and better functional capacity. Both factors were positively correlated with crystallized verbal knowledge.Conclusions: Executive functions in schizophrenia could be parsed into 2 partially related but separable subconstructs. Future efforts to elucidate functional outcomes as well as neurobiological underpinnings of schizophrenia may be facilitated by attending to the distinction between cognitive flexibility and abstraction.     

Depressive symptoms in schizophrenia.

OBJECTIVE: The authors assessed the presence and severity of depressive symptoms, as well as their associations with other clinical measures, in a group of mid- to late-life patients with schizophrenia who were not in a major depressive episode or diagnosed with schizoaffective disorder. METHOD: Sixty outpatients with schizophrenia between the ages of 45 and 79 years and 60 normal comparison subjects without major neuropsychiatric disorders, proportionally matched for age and gender, were studied. Depressive symptoms were rated primarily with the Hamilton Depression Rating Scale. Standardized instruments were also used to measure global psychopathology, positive and negative symptoms, abnormalities of movement, and global cognitive status. RESULTS: Depressive symptoms were more frequent and more severe in schizophrenic patients than in normal comparison subjects; 20% of the women with schizophrenia had a Hamilton depression scale score of 17 or more. Severity of depressive symptoms correlated with that of positive symptoms but not with age, gender, negative symptoms, extrapyramidal symptoms, or neuroleptic dose. CONCLUSIONS: Depressive symptoms are common in older patients with schizophrenia. They may be an independent, core component of the disorder or, alternatively, may be a by-product of severe psychotic symptoms.     

Neuroleptic discontinuation in clinical and research settings: scientific issues and ethical dilemmas.

The ethics of neuroleptic discontinuation in clinical and research settings are currently a topic of much discussion. The issues underlying this debate are complicated by the fact that these medications can be fairly effective in managing the symptoms and preventing relapse in schizophrenia and other psychotic disorders, yet these drugs have therapeutic limitations and their prolonged use is associated with a risk of serious, potentially persistent side-effects such as tardive dyskinesia. Over the past 47 years, the public perception about the value of neuroleptics has undergone dramatic shifts, based partly on the data available at different time periods. The risk-benefit ratio is better for the atypical antipsychotics compared to the conventional ones, but long-term experience with the newer agents has been limited. At present, a prudent strategy for most clinical and research purposes is to gradually taper the medications in clinically stable, carefully selected, consenting subjects to the lowest doses on which individual patients can be effectively maintained. In this article we discuss clinical, research, and ethical aspects of neuroleptic discontinuation. It is critical to protect potentially vulnerable patients with serious mental illnesses, while allowing them to benefit from appropriate investigations.     

Neurobehaviors and psychotic symptoms in Alzheimer's disease.

Psychotic symptoms are common in Alzheimer's disease (AD) and clinicoanatomical and neuropsychological evidence indicate an association between these symptoms and frontal lobe dysfunction. Neuro-behaviors associated with frontal dysfunction were assessed in Alzheimer's disease (AD) patients with (n = 20) and without psychotic symptoms (n = 21) matched for mean age, education, gender, and dementia severity. The Frontal Lobe Personality Scale (FLOPs) was completed by patient caregivers to measure behaviors typically associated with frontal dysfunction. Findings indicated that AD patients with psychotic symptoms exhibited significantly greater neurobehavioral dysfunction (FLOPs M = 130.69, SD = 24.70) than AD patients without psychotic symptoms (FLOPs M = 111.10, SD = 25.83). Subscale analyses indicated that psychotic AD patients were more dis-inhibited (M = 28.28, SD = 7.54) than patients without psychotic symptoms (M = 20.92, SD = 4.9). Findings are consistent with and contribute to previous neuropsychological and clinicoanatomical research suggesting increased frontal dysfunction in AD with psychotic symptoms and lend additional empirical support to subtyping AD based on the presence of psychotic symptoms. Furthermore, findings provide preliminary evidence indicating which specific type of neurobehavioral abnormalities are related to the presence of distressing psychotic symptoms.