Andrea Lammel

The diagnostic accuracy of the Revised Westmead PTA Scale as an adjunct to the Glasgow Coma Scale in the early identification of cognitive impairment in patients with mild traumatic brain injury

Background: Assessment of patients with mild traumatic brain injury (mTBI) is predominantly done using the Glasgow Coma Scale (GCS). While the GCS is universally accepted for assessment of severity of traumatic brain injury, it may not be appropriate to rely on the GCS alone when assessing patients with mTBI in prehospital settings and emergency departments. Objective: To determine whether administering the Revised Westmead Post-traumatic Amnesia (PTA) Scale (R-WPTAS) in addition to the GCS would increase diagnostic accuracy in the early identification of cognitive impairment in patients with mTBI. Methods: Data were collected from 82 consecutive participants with mTBI who presented to the emergency department of a level 1 trauma centre in Australia. A matched sample of 88 control participants who attended the emergency department for reasons other than head trauma was also assessed. All patients were assessed using the GCS, R-WPTAS and a battery of neuropsychological tests. Results: Patients with mTBI scored poorly compared with control patients on all measures. The R-WPTAS showed greater concurrent validity with the neuropsychological measures than the GCS and significantly increased prediction of group membership of patients with mTBI with cognitive impairment. Conclusions: The R-WPTAS significantly improves diagnostic accuracy in identifying patients with mTBI who may be in PTA. Administration takes less than 1 min, and since early identification of a patient’s cognitive status facilitates management decisions, it is recommended for routine use whenever the GCS is used.

A comprehensive neuropsychiatric study of elderly twins: The Older Australian Twins Study

The Older Australian Twins Study (OATS) was recently initiated to investigate genetic and environmental factors and their associations and interactions in healthy brain ageing and ageing-related neurocognitive disorders. The study extends the classic MZ-DZ design to include one or two equivalently aged siblings for each twin pair and utilizes the rich resources of the Australian Twin Registry. The study has a number of distinguishing features including comprehensive psychiatric, neuropsychological, cardiovascular, metabolic, and neuroimaging assessments, a longitudinal design and links with a brain donor program. The study measures many behavioral and environmental factors, but in particular lifetime physical and mental activity, physical and psychological trauma, loss of parent early in life, later losses and life events, early-life socioeconomic environment, alcohol and drug use, occupational exposure, and nutrition. It also includes comprehensive cardiovascular assessment, blood biochemistry, genetics and proteomics. The socio-demographic and health data on the first 172 pairs of twins participating in this study are presented. Prevalence of mild cognitive impairment is 12.8% and of dementia 1.5% in the sample. The target sample size is 1000, with at least 400 pairs of twins aged 65-90 years. The cohort will be assessed every two years, with in-depth assessments being repeated. OATS offers an excellent opportunity for collaboration with other similar studies as well as researchers who share the same interests.

Validation of the Abbreviated Westmead Post-traumatic Amnesia Scale: A brief measure to identify acute cognitive impairment in mild traumatic brain injury

Objective: To validate the use of the Abbreviated Westmead Post-traumatic Amnesia Scale (A-WPTAS) in the assessment of acute cognitive impairment in mild traumatic brain injury (mTBI). Methods: Data previously collected from 82 mTBI and 88 control participants using the Revised Westmead Post-traumatic Amnesia Scale (R-WPTAS) was converted to A-WPTAS scores and pass/fail classifications were calculated for both scales. Results: The proportion of failures on the R-WPTAS and the A-WPTAS did not differ and a similar number of mTBIs were classified on each. For mTBIs the relationship between the independent memory test and a pass/fail classification was the same for both scales. Bivariate logistic regressions revealed that mTBIs, relative to controls, were around 8 times more likely to fail the assessment (R-WPTAS: 95% CI: 3.70–18.87; A-WPTAS: 95% CI: 3.70–20.14). As verbal learning improved the likelihood of failure was reduced. Greater education was associated with a decreased likelihood of failure. The relationship between education and a fail performance was not sustained when education was adjusted for the effect of age, prior mTBI, blood alcohol level, injury status, verbal learning, and morphine administration. Conclusions: The A-WPTAS is a valid measure. The A-WPTAS may reduce the risk of failing to classify patients with mTBI by identifying and documenting acute cognitive impairment.

The contribution of twins to the study of cognitive ageing and dementia: The Older Australian Twins Study

Abstract The Older Australian Twins Study (OATS) is a major longitudinal study of twins, aged ≥ 65 years, to investigate genetic and environmental factors and their interactions in healthy brain ageing and neurocognitive disorders. The study collects psychiatric, neuropsychological, cardiovascular, metabolic, biochemical, neuroimaging, genomic and proteomic data, with two-yearly assessments, and is currently in its third wave. The initial cohort comprises 623 individuals (161 monozygotic and 124 dizygotic twin pairs; 1 MZ triplets; 27 single twins and 23 non-twin siblings), of whom 426 have had wave 2 assessment. A number of salient findings have emerged thus far which assist in the understanding of genetic contributions to cognitive functions such as processing speed, executive ability and episodic memory, and which support the brain reserve hypothesis. The heritability of brain structures, both cortical and subcortical, brain spectroscopic metabolites and markers of small vessel disease, such as lacunar infarction and white matter hyperintensities, have been examined and can inform future genetic investigations. Work on amyloid imaging and functional magnetic resonance imaging is proceeding and epigenetic studies are progressing. This internationally important study has the potential to inform research into cognitive ageing in the future, and offers an excellent resource for collaborative work.

Cognitive functioning in older twins: The Older Australian Twins Study

Aim:  To examine the concordance rates of common medical conditions and neurocognitive performance in monozygotic (MZ) and dizygotic (DZ) older twins.

Recent findings from the Older Australian Twins Study (OATS)

Background: The Older Australian Twins Study (OATS) was initiated to investigate genetic and environmental factors and their associations and interactions in healthy brain ageing and ageing-related neurocognitive disorders. Methods: Twins aged 65 years and older were recruited through the Australian Twin Registry. Participants receive a comprehensive neuropsychiatric assessment at baseline and a follow up every two years, along with MRI scans, clinical chemistry, inflammatory and metabolic markers, proteomics and genomics (Illumina Express). The cohort is nearing completion of Wave 2 and Wave 3 is planned from 2013. Initial analyses relate to cognitive function and neuroimaging measures. Results: The sample size of the cohort at Wave 1 is N1⁄4551 (MZ 135 pairs, DZ 106 pairs; singletons: MZ 20, DZ 25; Sibs 24). MZ twins have higher correlations than DZ twins on most neuropsychological tests, with the exception of some speeded tests. Multivariate genetic modelling showed that additive genetic factors explained 42 to 62% of the variance in five processing speed measures. As for executive functions, heritability of the four measures was variable, between 30 to 63%. The covariation between the processing speed measures and general cognitive ability, and between executive functions measures and general cognitive ability, were both attributable to a common genetic factor. Processing Speed was found to be the stronger mediator of age and episodic memory, as well as age and fluid intelligence, than executive functions. Proton magnetic resonance spectroscopy measures (NAA, Cr, Cho, mI) showed high heritability, being highest for NAA (N-acetyl aspartate). The global sulcal index also exhibited high heritability (79%). White matter hyperintensities were highly heritable with no significant age and sex effect. Conclusions: OATS provides a unique data set to examine genetic and environmental influences in a range of ageing-related phenotypes, in particular domains of cognitive function and brain chemistry not previously examined.