Psychophysiological diagnostics in alcohol dependency: Fourier analysis of pupillary oscillations and the receptor test for determination of cholinergic deficiency

Pupillary response to percutaneous auricular vagus nerve stimulation in alcohol withdrawal syndrome: A pilot trial

BACKGROUND

Autonomic symptoms in alcohol withdrawal syndrome (AWS) are associated with a sympathetic-driven imbalance of the autonomic nervous system. To restore autonomic balance in AWS, novel neuromodulatory approaches could be beneficial. We conducted a pilot trial with percutaneous auricular vagus nerve stimulation (pVNS) in AWS and hypothesized that pVNS will enhance the parasympathetic tone represented by a reduction of pupillary dilation in a parasympatholytic pharmacological challenge.

METHODS

Thirty patients suffering from alcohol use disorder, undergoing AWS, and stable on medication, were recruited in this open-label, single-arm pilot trial with repeated-measure design. Peripheral VNS (monophasic volt impulses of 1 msec, alternating polarity, frequency 1 Hz, amplitude 4 mV) was administered at the left cymba conchae for 72 h, followed by pupillometry under a tropicamide challenge. We assessed craving with a visual analog scale. We used pupillary mean as the dependent variable in a repeated-measures ANOVA (rmANOVA).

RESULTS

A repeated-measures ANOVA resulted in a significant difference for pupillary diameter across time and condition (F(2,116) = 27.97, p < .001, ηp2 > .14). Tukey-adjusted post hoc analysis revealed a significant reduction of pupillary diameter after pVNS. Alcohol craving was significantly reduced after pVNS (p < .05, Cohen's d = 1.27).

CONCLUSION

Our study suggests that pVNS activates the parasympathetic nervous system in patients with acute AWS, and that this activation is measurable by pupillometry. To this end, pVNS could be beneficial as a supportive therapy for AWS. Potential confounding effects of anti-craving treatment should be kept in mind.

Ocular parameters as an objective tool for the assessment of truck drivers fatigue

Ocular parameters are influenced by sleep derivation and the use of chemical substances which are two major causes for traffic accidents. We assessed the use of these parameters as an objective screening tool for a driver's fitness for duty. Pupillary diameter, pupil reaction to light and saccadic velocity were measured in 29 army truck drivers every morning for two months and compared to baseline measurements taken while the subjects were alert. An index which expressed the difference between study and baseline measurements was calculated, and drivers with significant deviation from baseline were disqualified and interviewed. Non-disqualified drivers served as controls. Twenty-nine percent of disqualified drivers reported sleeping less than the minimum of 7h required by army regulations compared with 8% of control drivers (p=0.01). Disqualified drivers had worse sleep quality the night before the test (Groningen Sleep Quality Scale, p=0.03) and incurred more accidents per driving day during their service (0.023 vs. 0.015 accidents/day, p=0.03). Two disqualified drivers admitted to using alcohol or sleeping pills. Thus, these ocular parameters may serve as a screening tool for drivers that are at high risk for driving. Drivers who were disqualified even once, tend to be involved in more motor vehicle accidents than their peers.

The role of brain oscillations as functional correlates of cognitive systems: a study of frontal inhibitory control in alcoholism

Event-related oscillations play a key role in understanding the brain dynamics and human information processing. In the present study, the Go/No-Go paradigm has been used to examine whether alcoholics have poor inhibitory control as compared to control subjects in terms of different oscillatory brain responses. The matching pursuit algorithm was used to decompose the event-related electroencephalogram into oscillations of different frequencies. It was found that alcoholics (n=58) showed significant reduction in delta (1.0-3.0 Hz) and theta (3.5-7.0 Hz) power during No-Go trials as compared to controls (n=29). This reduction was prominent at the frontal region. The decreased delta and theta power associated with No-Go processing perhaps suggests a deficient inhibitory control and information-processing mechanism. A neuro-cognitive model has been provided to explain the findings. It is suggested that the oscillatory correlates during cognitive processing can be an endophenotypic marker in alcoholism.

Psychometric- and quality-of-life assessment in long-term glioblastoma survivors

BACKGROUND

Multimodal treatment of patients with glioblastoma multiforme (GBM) allows an increasing number of patients to survive beyond one year. On account of various neurological and psychophysiological impairments, however, these patients may not benefit in terms of quality of life (QOL). We evaluated the subjective QOL, clinical psychophysiological and cognitive functions in patients with GBM surviving 18 months after diagnosis.

PATIENTS AND METHODS

Thirteen patients underwent psychophysiological and psychometric measurements for central-nervous activation, habituation of skin-conductance reaction, crystallized intelligence, verbal and psychovisual memory. QOL was assessed by the symptom check-list for somatization (SCS-Score).

RESULTS

We found various impairments such as central-nervous deactivation (n = 9) or high activation (n = 3), psychovegetative overexcitement (n = 3) or attenuation (n = 1), reduced verbal (n = 5) and/or psychovisual (n = 5) memory and loss in attention (n = 7) or concentration (n = 5). Severe physical symptoms (grade 5) were fatigue, convulsion, headache, nausea and micturition difficulties. Eleven patients expressed high satisfaction with life in general, whereas only 4 were satisfied with their general state of health. All patients were independent and 8 patients returned to work.

CONCLUSION

Despite various psychophysiological and cognitive impairments, subjective QOL appears mostly unaffected in this patient setting.

Tropicamide effects on pupil size and pupillary light reflexes in Alzheimer's and Parkinson's disease

Diagnostic tests for Alzheimer's disease (AD) involving tropicamide blockade of cholinergic oculomotor functions were examined in AD patients (n=15), Parkinson's disease (PD) patients (n=15), and non-clinical control (NC) participants (n=15). Pupillographic methods were used to measure pupil diameter and pupillary light reflexes after double-blind ocular administration of dilute tropicamide (0.01%) in one eye and saline in the other eye. Changes in pupil size were measured in bright background light and near-darkness. Tropicamide increased pupil diameter to a similar extent in all three groups in light and darkness. Tropicamide also reduced the amplitude and latency of the pupillary light reflex to a similar extent for all three groups. Tropicamide pupillary response tests, therefore, were not sensitive or specific diagnostic tests for AD. Peak constriction amplitude of the pupillary light reflex was significantly reduced in both eyes in AD and PD groups relative to non-clinical controls, but AD and PD groups did not differ significantly. The pupillary light reflex test, therefore, was sensitive to AD, but lacked adequate specificity. Finally, peak constriction amplitude correlated significantly with dementia severity and donepezil treatment may have partially normalized pupillary light reflex abnormalities in AD patients. The pupillary light reflex test, therefore, may index central cholinergic dysfunction associated with disease progression and improvement in cholinergic function associated with pharmacologic treatment response in AD.

The European acamprosate trials: conclusions for research and therapy

In an excellent methodological approach, the European acamprosate study project showed that acamprosate increases sobriety times. In one randomized prospective study (n = 260) comparing acamprosate and placebo, with a 1-year treatment phase and 1-year follow-up phase, the authors found that acamprosate is effective only in Lesch type I and type II patients. To investigate the possible influence of diagnostic subgrouping, we applied the Lesch typology in a co-work with the main researchers of the UK study. The UK results concerning acamprosate's effects in the types do not mirror the Vienna results, but the numbers of type I and type II patients, retrospectively found as included in the UK centers, were too small for any conclusions. The distribution of the types points to the fact that too many type III and IV patients had been included to give acamprosate the chance to be effective. Following our typology and also these studies, we developed special treatment approaches. For relapse prevention studies, the cumulative abstinence duration together with the Lesch typology seems to be promising.