Study investigating executive function in schizophrenia patients and their unaffected siblings

Background: Schizophrenia (SCZ) is a serious genetic mental illness. Most research indicates that executive impairment has a certain genetic predisposition. The shared neuropathological characteristics of patients with schizophrenia and their siblings might reveal intermediate phenotypes in behavior that could be used to further characterize the illness. Methods: Our study involved 32 schizophrenia patients, 32 unaffected siblings,and 33 healthy controls. The three groups underwent a computerized version of the Wisconsin Card Sorting Test (WCST) and a battery of cognitive neuropsychological assessments. These tests evaluated executive function and several cognitive domains. Results: In this study, the WCST results demonstrate that the total correct (TC), total error (TE), perseverative response (PR) and perseverative error (PE) scores in the SZ group were significantly lower than those in the HC group (TC (p=0.011), TE (p<0.001), PR (p=0.007) and PE (p=0.002)), and compared to the unaffected siblings, we found significant differences in TE (p=0.003). Moreover, significant differences were observed between the unaffected siblings and healthy controls as follows: TC (p=0.034), TE (p=0.008), PR (p=0.016) and PE (p=0.013). Conclusion: The schizophrenia patients and their siblings performed worse in the WCST test than the healthy controls. This result supports the claim that the development of functional impairment is not unique to schizophrenia patients and that unaffected siblings may have a certain level of abnormal brain function.Neurological abnormalities lead to abnormal functioning in siblings and patients,suggesting that genetics plays a considerable role in such results.

Reducing Aphasic Perseverations: A Case Study

The purpose of this study was to measure outcomes resulting from a treatment designed to reduce aphasic perseverations by decreasing activation of the perseverative response and increasing activation of the target response. A single-subject design was used. A Spanish-speaking male with moderate-to-severe receptive-expressive aphasia participated in this study. Treatment involved the use of systematic reduction of interstimulus interval paired with semantic feature analysis. The treatment resulted in a decrease in perseveration, but only minor increases in naming accuracy on trained and untrained stimuli. In addition, an increase in overall verbal output was observed. Decreased perseveration was maintained during follow-up. Outcomes suggest the treatment successfully reduces perseveration and increases verbal output. Additional research is needed to evaluate the effectiveness of this treatment.

Long-Term Perseveration in Alzheimer’s Disease: A Case Report

The most common clinical sign of Alzheimer's disease (AD) is progressive memory loss. Presented here is a case of AD who, despite ultimate profound dementia with severe amnesia, showed retention of a perseverative response she developed during 26 encounters, over 4.5 years, with the Brown–Peterson distractor test. From Test 9 onwards, she responded from the first distractor-filled trial with one consonant trigram, appearing in none of the seven test forms given her. At Test 26, she could not repeat heard trigrams yet faithfully responded with her perseverative trigram. The trigram, ostensibly declarative information, apparently became part and parcel of the task's procedure. Although perseveration is a form of impairment probably resulting from Alzheimer pathology involving frontal and parietal cortex, it may also reflect a form of preserved memory, albeit distorted, supported by posterior cortical regions spared in AD.

Probability Learning by Aphasic Subjects

Nine aphasic and nine nonaphasic patients participated in a two-choice probability learning experiment in which they attempted to turn on a set of red “reinforcement” lights by pressing push buttons. During the first 50 trials, responses on one push button turned on the lights 70 times as often as responses on the other. During the next 50 trials, the reinforcement ratio was 5/1 in favor of the push button that first delivered maximum reinforcement. During the following five 50-trial blocks the ratio was changed successively to 2/1, 1/1, 1/2, 1/5, 1/70. Most aphasic subjects changed their response patterns to accord with the changing reinforcement ratios. Between-subject variability was greater for aphasic subjects than for nonaphasic subjects, and seven aphasic subjects exhibited “perseverative” response patterns in early reinforcement ratios. The performance of two aphasic subjects did not appear to be influenced by the reinforcement ratios in the first session. However, further observation and experimental treatment of these two subjects resulted in appropriate changes in their performance. The results of this study suggest that behavior-shaping techniques involving changing reinforcement schedules can be used in clinical treatment of aphasic patients.