Exploring What the Austin Maze Measures: A Comparison Across Conventional and Computer Versions

Association between nocturnal activity of the sympathetic nervous system and cognitive dysfunction in obstructive sleep apnoea

Obstructive sleep apnoea (OSA) is associated with repetitive breathing obstructions during sleep. These episodes of hypoxia and associated arousals from sleep induce physiological stress and nocturnal over-activation of the sympathetic nervous system (SNS). One consequence of OSA is impairment in a range of cognitive domains. Previous research into cognitive impairment in OSA have focussed on intermittent hypoxia and disrupted sleep, but not nocturnal over-activation of the SNS. Therefore, we investigated whether nocturnal over-activity of the SNS was associated with cognitive impairments in OSA. The extent of nocturnal SNS activation was estimated from heart rate variability (HRV), pulse wave amplitude (PWA) and stress response biomarkers (cortisol and glucose levels). OSA severity was significantly associated with PWA indices and the HRV low frequency/ high frequency ratio (p < 0.05). Morning blood glucose levels were significantly associated with the duration of a blood oxygen saturation (SaO₂) < 90% (p < 0.01). PWA and HRV were significantly associated with the time taken to perform a task involving visuospatial functioning (p < 0.05), but not with impairments in sustained attention, reaction time or autobiographical memory. These results suggest that the visuospatial dysfunction observed in people with OSA is associated with increased nocturnal activity of the SNS.

Differential associations of hypoxia, sleep fragmentation, and depressive symptoms with cognitive dysfunction in obstructive sleep apnea

Obstructive sleep apnea (OSA) is characterized by recurrent episodes of partial or complete cessation of breathing during sleep and increased effort to breathe. This study examined patients who underwent overnight polysomnographic studies in a major sleep laboratory in Saudi Arabia. The study aimed to determine the extent to which intermittent hypoxia, sleep disruption, and depressive symptoms are independently associated with cognitive impairments in OSA. In the sample of 90 participants, 14 had no OSA, 30 mild OSA, 23 moderate OSA, and 23 severe OSA. The findings revealed that hypoxia and sleep fragmentation are independently associated with impairments of sustained attention and reaction time (RT). Sleep fragmentation, but not hypoxia, was independently associated with impairments in visuospatial deficits. Depressive symptoms were independently associated with impairments in the domains of sustained attention, RT, visuospatial ability, and semantic and episodic autobiographical memories. Since the depressive symptoms are independent of hypoxia and sleep fragmentation, effective reversal of cognitive impairment in OSA may require treatment interventions that target each of these factors.

The practice of clinical neuropsychology in Australia

OBJECTIVE

This paper describes the development and practice of clinical neuropsychology in Australia.

METHOD

Clinical Neuropsychology has shown rapid growth in Australia over the past three decades. Comprehensive and specialized training programs are producing high quality graduates who are employed in a broad range of settings or private practice.

RESULTS

Australia now has a substantial number of clinical neuropsychologists with specialist training. Whilst the majority of Australian clinical neuropsychologists still undertake assessment predominantly, there are growing opportunities for clinical neuropsychologists in rehabilitation and in a broad range of research contexts. Cultural issues relating to the assessment of Indigenous Australians and immigrants from many countries present significant challenges. Some major contributions have been made in the realms of test development and validation across various age groups. Australian clinical neuropsychologists are also contributing significantly to research in the fields of traumatic brain injury, aging and dementias, epilepsy, memory assessment, rehabilitation, substance abuse, and other psychiatric disorders.

CONCLUSION

Expansion of roles of clinical neuropsychologists, in domains such as rehabilitation and research is seen as essential to underpin continuing growth of employment opportunities for the profession.

Visuospatial Learning in Traumatic Brain Injury: An Examination of Impairments using the Computerised Austin Maze Task

An important aspect of cognitive functioning that is often impaired following traumatic brain injury (TBI) is visuospatial learning and memory. The Austin Maze task is a measure of visuospatial learning that has a long history in both clinical neuropsychological practice and research, particularly in individuals with TBI. The aim of this study was to evaluate visuospatial learning deficits following TBI using a new computerised version of the Austin Maze task. Twenty-eight individuals with moderate-to-severe TBI were compared to 28 healthy controls on this task, together with alternative neuropsychological measures, including the WAIS-III Digit Symbol and Digit Span subtests, the Trail Making Test, WMS-III Logical Memory, and Rey Osterrieth Complex Figure Test. The results demonstrated that TBI individuals performed significantly more poorly on the Austin Maze task than control participants. The Austin Maze task also demonstrated good convergent and divergent validity with the alternative neuropsychological measures. Thus, the computerised version of the Austin Maze appears to be a sensitive measure that can detect visuospatial learning impairments in individuals with moderate-to-severe TBI. The new computerised version of the task offers much promise in that it is more accessible and easier to administer than the conventional form of the test.