Postural control and lifetime alcohol consumption in alcohol-dependent patients

Centre of pressure changes during stance but not during gait in young women after alcohol intoxication

Background

Women are underrepresented in research focused on alcohol (e.g., Brighton, Moxham & Traynor, 2016; DOI 10.1097/JAN.0000000000000136) despite the changing patterns of alcohol consumption, which has been increasing in women in recent decades. The purpose of this study was to analyse the relationship between habitual alcohol consumption and centre of pressure (CoP) parameters during stance and gait while intoxicated by alcohol.

Methods

Thirty women (24.39 ± 2.93 years) participated in this study. All participants were asked to answer the AUDIT questionnaire. Stance and gait analysis were repeated under two conditions on a Zebris platform (FDM GmbH; Munich, Germany): when the participants were sober (0.00% breath alcohol concentration, BrAC) and when they were in an intoxicated state (0.11% BrAC). Participants were divided by their AUDIT score into a low-risk alcohol consumption group (n = 15; AUDIT score: 3 to 6) and a hazardous alcohol consumption group (n = 15; AUDIT score: 7 to 13).

Results

No statistical difference was observed in stance and gait parameters when comparing the low-risk and hazardous groups under 0.00% BrAC and 0.11% BrAC conditions. A statistically significant difference was observed when comparing 0.00% BrAC and 0.11% BrAC conditions within each group. This significant difference was found in CoP path length and CoP average velocity during quiet stance. However, no statistically significant differences were observed in CoP parameters during gait. An alcohol intoxication of 0.11% BrAC was not sufficient to cause statistically significant impairments in butterfly parameters of gait.

Characterization of cerebellar ataxia in chronic alcoholics using the International Cooperative Ataxia Rating Scale (ICARS)

BACKGROUND

Alcoholism is the most common cause of cerebellar dysfunction, yet estimates of the incidence of alcoholic cerebellar degeneration (ACD) vary greatly, with differences in methodologies contributing to these disparate findings. This study set out to characterize the frequency and pattern of clinical signs of ACD in an alcoholic group using the International Cooperative Ataxia Rating Scale (ICARS).

METHODS

We compared the performance of 49 alcoholics and 29 control participants. The relative contributions of demographic and alcohol consumption variables to ICARS scores in the alcoholic group were also examined.

RESULTS

The alcoholic group demonstrated significantly poorer performance on all of the ICARS subscales as compared with the control group. Within the alcoholic group, performance was more impaired on the speech scale than on all of the other scales, except the lower limb component of the kinetic scale, and less impaired on the oculomotor scale compared with all other scales. Years of heavy drinking and lifetime alcohol consumption correlated with total ICARS scores; however, maximum daily consumption was actually negatively correlated with ICARS scores. Of the alcohol history variables, years of heavy drinking was the best predictor of total ICARS scores, making a 19% unique contribution, followed by the period of abstinence from alcohol, which uniquely contributed 7% of the variance. There were high correlations between age and male gender and the alcohol consumption variables; however, age and gender were still found to uniquely contribute 5 and 7% respectively to the variance in total ICARS scores.

CONCLUSIONS

ACD may affect up to two-thirds of chronic alcoholics. Assessing the number of years an individual has been drinking beyond a certain threshold can give a good indication of the likelihood of ACD. Age, gender, and the source of the clinical sample may significantly contribute to the prevalence of ACD and require further detailed investigation.

Alcohol and Its Impact on Motor Control

Acute and chronic alcohol intoxications have particularly deleterious consequences on physiological processes involving motor control and balance. This paper describes alcohol impairments to the central motor system networks in social and heavy drinkers and in individuals dependent on alcohol with or without neurological diseases.

Physiological and focal cerebellar substrates of abnormal postural sway and tremor in alcoholic women

BACKGROUND

Posturography analysis of static balance reveals marked sway and tremor in sober alcoholic men related to anterior vermis volume but can be attenuated by simple visual or tactile cues or alterations in stance. Whether alcoholic women, whose ataxia can persist with prolonged sobriety, exhibit the same physiological signature of balance instability and relation to cerebellar vermian volume as alcoholic men or can benefit from stabilizing factors is unknown.

METHODS

Groups comprised 15 alcohol-dependent women, alcohol-free (median 3 months) and 29 control women. Groups were matched in age, demographic features, and finger movement speed and underwent balance platform testing and magnetic resonance imaging scanning.

RESULTS

Alcoholic women exhibited excessive sway path length (.6 SD), more dramatic in the anterior-posterior than medial-lateral direction. Truncal tremor, measured as peak sway velocity frequency, was disproportionately great in the 5 Hz to 7 Hz band of alcoholics. Control subjects and alcoholics exhibited sway and tremor reduction with visual, tactile, or stance-stabilizing conditions, which aided both groups equally well; thus, alcoholic women never achieved normal stability. Smaller anterior vermian volumes selectively correlated with longer sway path and higher 5 Hz to 7 Hz peak sway velocity.

CONCLUSIONS

Sway and tremor abnormalities and the selective relations between greater sway and 5 Hz to 7 Hz tremor and smaller volumes of the anterior vermis had not heretofore been described in abstinent alcoholic women. Reduction in sway and tremor with stabilizing factors indicate that adaptive mechanisms involving sensorimotor integration can be invoked to compensate for vermian-related dysfunction.

Mechanisms of postural control in alcoholic men and women: biomechanical analysis of musculoskeletal coordination during quiet standing

BACKGROUND

Excessive sway during quiet standing is a common sequela of chronic alcoholism even with prolonged sobriety. Whether alcoholic men and women who have remained abstinent from alcohol for weeks to months differ from each other in the degree of residual postural instability and biomechanical control mechanisms has not been directly tested.

METHOD

We used a force platform to characterize center-of-pressure biomechanical features of postural sway, with and without stabilizing conditions from touch, vision, and stance, in 34 alcoholic men, 15 alcoholic women, 22 control men, and 29 control women. Groups were matched in age (49.4 years), general intelligence, socioeconomic status, and handedness. Each alcoholic group was sober for an average of 75 days.

RESULTS

Analysis of postural sway when using all 3 stabilizing conditions versus none revealed diagnosis and sex differences in ability to balance. Alcoholics had significantly longer sway paths, especially in the anterior-posterior direction, than controls when maintaining erect posture without balance aids. With stabilizing conditions the sway paths of all groups shortened significantly, especially those of alcoholic men, who demonstrated a 3.1-fold improvement in sway path difference between the easiest and most challenging conditions; the remaining 3 groups, each showed a approximately 2.4-fold improvement. Application of a mechanical model to partition sway paths into open-loop and closed-loop postural control systems revealed that the sway paths of the alcoholic men but not alcoholic women were characterized by greater short-term (open-loop) diffusion coefficients without aids, often associated with muscle stiffening response. With stabilizing factors, all 4 groups showed similar long-term (closed loop) postural control. Correlations between cognitive abilities and closed-loop sway indices were more robust in alcoholic men than alcoholic women.

CONCLUSIONS

Reduction in sway and closed-loop activity during quiet standing with stabilizing factors shows some differential expression in men and women with histories of alcohol dependence. Nonetheless, enduring deficits in postural instability of both alcoholic men and alcoholic women suggest persisting liability for falling.

Motor functioning and alcohol dependence

BACKGROUND

Autopsy and neuroimaging research in stably abstinent alcoholics illuminated structural and functional abnormalities in brain areas that organize and coordinate motor functioning. Researchers that used behavioural tasks to measure motor functioning found that abstinent alcoholics perform worse than healthy controls. These researchers however did not analyze timed responses into their cognitive and motor components. They thus were unable to decide which aspects of information processing are impaired. We here used a Fitts' task to examine differences in cognitive and motor components between abstinent alcoholics and healthy controls.

METHODS

Fifty-two abstinent alcoholics and 52 healthy controls participated in this research design. Fine motor functioning was assessed by means of the Fitts' task.

RESULTS

Abstinent alcoholics needed more time to perform timed responses than healthy controls. As both reaction and movement times were higher in abstinent alcoholics, both cognitive and motor processes seem to be impaired. When the task became more difficult (small targets instead of large targets) abstinent alcoholics needed proportionally more time to give the correct response than healthy controls. This phenomenon solely applied to movement times.

CONCLUSIONS

These research data indicate that abstinent alcoholics are somewhat impaired on a behavioral level. The execution of timed responses indeed was lengthier in abstinent alcoholics than in healthy controls. As both cognitive and motor processes were impaired, we here assume that both central and peripheral processes are affected by progressive alcohol intake. Abstinent alcoholics also have more difficulties to adapt their motor responses to changing task conditions.

Effect of vision, touch and stance on cerebellar vermian-related sway and tremor: a quantitative physiological and MRI study

Postural balance is impaired in individuals with pathology of the anterior superior vermis of the cerebellum. Chronic alcoholism, with its known vermian pathology, provides a viable model for studying the relationship between cerebellar pathology and postural stability. Decades of separate study of recovering alcoholics and post-mortem neuroanatomical analysis have demonstrated vermian pathology but few studies have used quantitative posturography, acquired concurrently with quantitative neuroimaging, to establish whether this brain structure-function relationship is selective in vivo. Here, 30 healthy men and 39 chronic alcoholic men, abstinent from alcohol for several months, underwent MRI for volumetric quantitation of the cerebellar vermis and three comparison brain regions, the cerebellar hemispheres, supratentorial cortex and corpus callosum. All subjects also participated in an experiment involving a force platform that measured sway path length and tremor during static standing balance under four sensory conditions and two stance conditions. Three novel findings emerged: (i) sway path length, a physiological index of postural control, was selectively related to volume of the cerebellar vermis and not to any comparison brain region in the alcoholics; (ii) spectral analysis revealed sway prominence in the 2-5 Hz band, another physiological sign of vermian lesions and also selectively related to vermian volume in the alcoholics; and (iii) despite substantial postural sway in the patients, they successfully used vision, touch and stance to normalize sway and reduce tremor. The selective relationship of sway path to vermian but not lateral cerebellar volume provides correlational evidence for functional differentiation of these cerebellar regions. Improvement to virtual normal levels in balance and reduction in sway and tremor with changes in vision, touch and stance provide evidence that adaptive mechanisms recruiting sensorimotor integration can be invoked to compensate for underlying cerebellar vermian-related dysfunction.

Is there a relationship between somatic and autonomic neuropathies in chronic alcoholics?

We investigated the relationship between somatic and autonomic neuropathy in 40 chronic alcoholics. Electromyographic and neurographic studies of upper and lower limbs and a battery of six cardiovascular reflex tests were carried out. A score for somatic or autonomic neuropathy was calculated. All parameters were investigated for possible relationship with total life dose (TLD) of alcohol intake. Somatic neuropathy was detected in 25 patients (62.5%) and autonomic neuropathy in 13 patients (32.5%). Nineteen patients (47.5%) presented only a somatic neuropathy, six patients (15%) had only an autonomic neuropathy, and seven (17.5%) had a combined somatic and autonomic neuropathy. TLD was significantly higher in the group of patients with combined neuropathy than in the group with isolated somatic neuropathy. There was no significant correlation between laboratory parameters of somatic and autonomic neuropathy. Our findings do not support the existence of a parallel involvement of peripheral somatic and autonomic cardiovascular nerve fibers in chronic alcoholism.