Randolph W. Parks

The neural basis of visuospatial perception in Alzheimer's disease and healthy elderly comparison subjects: An fMRI study

The neural basis of visuospatial deficits in Alzheimers disease is unclear. We wished to investigate the neural basis of visuospatial perception in patients with Alzheimers disease compared with healthy elderly comparison subjects using functional magnetic resonance imaging (fMRI). Twelve patients with AD and thirteen elderly comparison subjects were investigated. The patients were recruited from the local clinic and comparison subjects were from spouses and community. All participants underwent fMRI whilst viewing visuospatial stimuli and structural MRI, and findings were analysed using voxel-based morphometry. The comparison group activated V5, superior parietal lobe, parieto-occipital cortex and premotor cortices. The AD group demonstrated hypoactivation in the above regions and instead showed greater activation in inferior parietal lobule and activated additional areas. There was no structural atrophy above and beyond that found globally in patients in the identified regions of BOLD activation. To our knowledge, this is the first study to explore the neuroanatomy of perception of depth and motion in Alzheimers disease. These specific functional deficits in AD provide evidence for an underlying patho-physiological basis for the clinically important symptom of visuospatial disorientation in patients with AD.

Time perception and its neuropsychological correlates in patients with schizophrenia and in healthy volunteers

Disordered time perception has been reported in schizophrenia. We investigated time perception dysfunction and its neuropsychological correlates in patients with schizophrenia. Participants comprised 38 patients and 38 age- and sex-matched healthy volunteers who were compared in an auditory temporal bisection paradigm using two interval ranges (a 400/800 ms condition and a 1000/2000 ms condition). In the temporal bisection, subjects were required to categorise a probe duration as short or long, based upon the similarity with two reference durations. All subjects also completed a battery of neuropsychological tests measuring sustained attention, short- and long-term memory and executive function. In the 400/800 ms condition, patients judged durations significantly shorter than did control subjects. Patients also exhibited decreased temporal sensitivity in both conditions. We found in both groups a negative association between temporal sensitivity and sustained attention for the 400/800 ms condition, and between temporal sensitivity and long-term memory for the 1000/200 ms condition. In patients, short-term memory performance was negatively associated with duration judgement in both conditions, while executive dysfunction was correlated to a general performance deficit in the 400/800 ms condition. These findings suggest the possibility that time perception abnormalities in schizophrenia are part of neuropsychological dysfunction and are likely to adversely impact upon activity of daily living.

Increased regional cerebral glucose metabolism and semantic memory performance in Alzheimer's disease: A pilot double blind transdermal nicotine positron emission tomography study

Nicotinic receptor dysfunction and impaired semantic memory occur early in Alzheimers disease patients (AD). Previous research implied that nicotines ability to enhance alertness, arousal, and cognition in a number of nonclinical populations was a function of its ability to stimulate CNS nicotinic cholinergic receptors. In this study it was hypothesized that transdermal administration of nicotine would increase both regional cerebral glucose metabolism (rCMRglc) and semantic memory (as assessed by verbal fluency). Two mild AD and two elderly controls underwent positron emission tomography scanning during a double blind nicotinic agonist verbal fluency challenge procedure. rCMRglc increases occurred in both AD patients, but not controls. In the two AD patients, verbal fluency scores increased by an average of 17%. One elderly controls verbal fluency increased, and the other decreased. These findings suggest that nicotines effect on metabolism and verbal fluency is due to its ability to stimulate the cholinergic system.

Neurobehavioural and cognitive function is linked to childhood trauma in homeless adults

OBJECTIVES To describe levels of traumatic childhood events in a sample of homeless individuals and to assess the contribution of traumatic events to neurobehavioural traits (measured with the Frontal Systems Behaviour Scale, FrSBe) and general cognitive function (IQ). DESIGN A sample of 55 homeless adults was recruited from homeless services in the city of Sheffield, UK. All were interviewed to acquire substance misuse information, record experiences of childhood trauma, and assess cognitive and neurobehavioural traits. METHODS Experiences of abuse and neglect were assessed with the Childhood Trauma Questionnaire. Participants also completed the Wechsler Abbreviated Scale of Intelligence and the FrSBe, which was completed with respect to current behaviour and conduct prior to homelessness. RESULTS Around three-quarters of the sample scored in the clinically significant range for current neurobehavioural impairment. They also reported high levels of impairment when rating retrospectively for the period before they were homeless. The mean group IQ was below average at 88. Abuse or neglect during their upbringing was reported by 89% of the sample. Emotional abuse, emotional neglect, and physical neglect were all positively correlated with total FrSBe scores. Sexual abuse, emotional neglect, and physical neglect were all negatively correlated with IQ. The associations between trauma and IQ and neurobehavioural traits appear generally unrelated to the presence of substance misuse in the sample. CONCLUSION Our homeless sample displayed relatively low IQ with high levels of neurobehavioural impairment. Our evidence suggests that these neuropsychological factors may, in part, constitute a long-term consequence of childhood trauma.

A new dissimilarity measure for finding semantic structure in category fluency data with implications for understanding memory organization in schizophrenia.

The ordering of words in category fluency lists is indicative of the semantic distance between items in conceptual memory. Several studies have concluded from structural analyses of such data, using cluster analysis or multidimensional scaling, that the semantic memory of patients with schizophrenia is more disorganized than that of controls. Previous studies have based their analyses on a measure of average interitem dissimilarity devised by A. S. Chan et al. (1993). Here the authors derive a new and improved method of determining dissimilarity and show that when this measure is applied to the fluency lists of patients with schizophrenia, the average pattern of organization for the animal category has similar structure to that of controls, but with greater variability between individuals.

Time Perspective, Depression, and Substance Misuse Among the Homeless

Using the Zimbardo Time Perspective Inventory (ZTPI; P. G. Zimbardo & J. N. Boyd, 1999), the authors found that homeless people, in comparison with a control group, had a significantly more negative outlook concerning their past and present as evinced by high Past-Negative and Present-Fatalistic scores and low Past-Positive scores on the ZTPI. However, the homeless individuals were almost indistinguishable from control participants on measures of Present-Hedonism and Future thinking. The homeless individuals had significantly higher levels of depression, with 31 out of 50 (62%) reaching criteria for probable depression. However, this finding was unrelated to their atypical time perspective. There was no significant relation between substance misuse and time perspective. Despite their current difficulties, including depression and drug abuse, the homeless individuals maintained a propensity toward future thinking characterized by striving to achieve their goals.

Treatment Effects of Therapeutic Cholinesterase Inhibitors on Visuospatial Processing in Alzheimer's Disease: A Longitudinal Functional MRI Study

Background/Aims: Visuospatial impairments are known to occur in Alzheimer’s disease (AD). We hypothesised that functional magnetic resonance imaging (fMRI) response in task-related brain regions would be impaired in patients with AD during the task and that treatment with acetyl cholinesterase inhibitors would enhance activations in brain regions concerned with this visual perceptual processing. Method: Ten AD subjects were neuropsychologically assessed and underwent fMRI imaging whilst performing a series of visuospatial perception tasks, before and after treatment with acetyl cholinesterase inhibitors. Eleven healthy elderly comparison subjects were also scanned twice. Results: Regions of increased brain activation in AD included the left precuneus, left cuneus, left supramarginal gyrus, right parieto-temporal cortex and right inferior parietal lobule. Further, increased activation in the left precuneus was found to correlate significantly with improved functioning of activities of daily living. Conclusions: We believe this to be the first fMRI study that, after controlling for the confound of repeat scanning, demonstrates altered patterns of brain activation associated with visuospatial processing following treatment in patients with AD. The treatment-related improvement of visual perception in AD may rely on enhanced attentional mechanisms, thereby possibly supporting independent living through improvement on activities of daily living.

Parallel distributed processing and neuropsychology: a neural network model of Wisconsin Card Sorting and verbal fluency.

Neural networks can be used as a tool in the explanation of neuropsychological data. Using the Hebbian Learning Rule and other such principles as competition and modifiable interlevel feedback, researchers have successfully modeled a widely used neuropsychological test, the Wisconsin Card Sorting Test. One of these models is reviewed here and extended to a qualitative analysis of how verbal fluency might be modeled, which demonstrates the importance of accounting for the attentional components of both tests. Difficulties remain in programming sequential cognitive processes within a parallel distributed processing (PDP) framework and integrating exceedingly complex neuropsychological tests such as Proverbs. PDP neural network methodology offers neuropsychologists co-validation procedures within narrowly defined areas of reliability and validity.

Voice familiarity engages auditory cortex

Familiarity with a speakers voice has been shown to enhance its auditory processing, implicating physiological effects at the level of the auditory cortex, although auditory cortical involvement has not previously been demonstrated. Eleven healthy right-handed male participants performed two tasks during blood oxygenation level-dependant functional MRI at 1.5 T. Both tasks used the same vocal stimuli. In task 1, they classified speakers as familiar or unfamiliar. In task 2, they judged stimuli as being in the right or left auditory field. Our analysis showed an area of auditory cortex on the lower bank of the superior temporal sulcus that was preferentially activated by familiar voices in both tasks. Familiar voices may elicit access to detailed sensory expectations, allowing enhanced auditory cortical processing.

Speech and language therapy intervention in schizophrenia: a case study

BACKGROUND There is a significant body of evidence documenting the speech and language abnormalities found in adult psychiatric disorders. These speech and language impairments can create additional social barriers for the individual and may hinder effective communication in psychiatric treatment and management. However, the role of speech and language therapy in this patient population has not been extensively studied. AIMS Speech and language therapy is reported in a 53-year-old adult male patient who presented with severe poverty of speech as part of his diagnosis of schizophrenia. The aims of speech and language therapy focused on increasing the patients verbal communication using a combination of traditional and non-traditional speech and language therapy methods. METHODS & PROCEDURES Two phases of speech and language therapy were implemented. The first phase focused on desensitizing the patient to verbal communication. The second phase developed the patients language productivity and increased his awareness of his social communication skills. Five separate measures were taken as baselines which were repeated at the end of the intervention. OUTCOMES & RESULTS Post-intervention scores showed that the intervention was partly successful. The patients verbal communication increased and he developed more appropriate social communication skills. His negative attitude to communication remained unchanged even though his self-evaluative status improved. CONCLUSIONS The intervention is discussed in terms of the pre- and post-intervention measures and the role of speech and language therapy in schizophrenia. The study suggests that speech and language therapy can contribute to the understanding and management of schizophrenia and other adult psychiatric disorders.