Hyperoxygenation effect on cognitive functioning in the aged

Glitches in the brain: the dangerous relationship between radiotherapy and brain fog

Up to approximately 70% of cancer survivors report persistent deficits in memory, attention, speed of information processing, multi-tasking, and mental health functioning, a series of symptoms known as "brain fog." The severity and duration of such effects can vary depending on age, cancer type, and treatment regimens. In particular, every year, hundreds of thousands of patients worldwide undergo radiotherapy (RT) for primary brain tumors and brain metastases originating from extracranial tumors. Besides its potential benefits in the control of tumor progression, recent studies indicate that RT reprograms the brain tumor microenvironment inducing increased activation of microglia and astrocytes and a consequent general condition of neuroinflammation that in case it becomes chronic could lead to a cognitive decline. Furthermore, radiation can induce endothelium reticulum (ER) stress directly or indirectly by generating reactive oxygen species (ROS) activating compensatory survival signaling pathways in the RT-surviving fraction of healthy neuronal and glial cells. In particular, the anomalous accumulation of misfolding proteins in neuronal cells exposed to radiation as a consequence of excessive activation of unfolded protein response (UPR) could pave the way to neurodegenerative disorders. Moreover, exposure of cells to ionizing radiation was also shown to affect the normal proteasome activity, slowing the degradation rate of misfolded proteins, and further exacerbating ER-stress conditions. This compromises several neuronal functions, with neuronal accumulation of ubiquitinated proteins with a consequent switch from proteasome to immunoproteasome that increases neuroinflammation, a crucial risk factor for neurodegeneration. The etiology of brain fog remains elusive and can arise not only during treatment but can also persist for an extended period after the end of RT. In this review, we will focus on the molecular pathways triggered by radiation therapy affecting cognitive functions and potentially at the origin of so-called "brain fog" symptomatology, with the aim to define novel therapeutic strategies to preserve healthy brain tissue from cognitive decline.

The potential of hyperbaric oxygen as a therapy for neurodegenerative diseases

The World Health Organization estimates that by the year 2040, neurodegenerative diseases will be the second leading cause of death in developed countries, overtaking cancer-related deaths and exceeded only by cardiovascular disease-related death. The search for interventions has therefore become paramount to alleviate some of this burden. Based on pathways affected in neurodegenerative diseases, hyperbaric oxygen treatment (HBOT) could be a good candidate. This therapy has been used for the past 50 years for conditions such as decompression sickness and wound healing and has been shown to have promising effects in conditions associated with neurodegeneration and functional impairments. The goal of this review was to explore the history of hyperbaric oxygen therapy, its uses, and benefits, and to evaluate its effectiveness as an intervention in treating neurodegenerative diseases. Additionally, we examined common mechanisms underlying the effects of HBOT in different neurodegenerative diseases, with a special emphasis on epigenetics.

Hyperbaric oxygen therapy for healthy aging: From mechanisms to therapeutics

Hyperbaric oxygen therapy (HBOT), a technique through which 100% oxygen is provided at a pressure higher than 1 atm absolute (ATA), has become a well-established treatment modality for multiple conditions. The noninvasive nature, favorable safety profile, and common clinical application of HBOT make it a competitive candidate for several new indications, one of them being aging and age-related diseases. In fact, despite the conventional wisdom that excessive oxygen accelerates aging, appropriate HBOT protocols without exceeding the toxicity threshold have shown great promise in therapies against aging. For one thing, an extensive body of basic research has expanded our mechanistic understanding of HBOT. Interestingly, the therapeutic targets of HBOT overlap considerably with those of aging and age-related diseases. For another, pre-clinical and small-scale clinical investigations have provided validated information on the efficacy of HBOT against aging from various aspects. However, a generally applicable protocol for HBOT to be utilized in therapies against aging needs to be defined as a subsequent step. It is high time to look back and summarize the recent advances concerning biological mechanisms and therapeutic implications of HBOT in promoting healthy aging and shed light on prospective directions. Here we provide the first comprehensive overview of HBOT in the field of aging and geriatric research, which allows the scientific community to be aware of the emerging tendency and move beyond conventional wisdom to scientific findings of translational value.

Impact of Hyperbaric Oxygen Therapy on Cognitive Functions: a Systematic Review

Hyperbaric oxygen therapy (HBOT) is a modality of treatment in which patients inhale 100% oxygen inside a hyperbaric chamber pressurised to greater than 1 atmosphere. The aim of this review is to discuss neuropsychological findings in various neurological disorders treated with HBOT and to open new perspectives for therapeutic improvement. A literature search was conducted in the MEDLINE (via PubMed) database from the inception up 10 May 2020. Eligibility criteria included original articles published in English. Case studies were excluded. Full-text articles were obtained from the selected studies and were reviewed on the following inclusion criteria (1) performed cognitive processes assessment (2) performed HBOT with described protocol. Two neuropsychologists independently reviewed titles, abstracts, full texts and extracted data. The initial search retrieved 1024 articles, and a total of 42 studies were finally included after applying inclusion and exclusion criteria. The search yielded controversial results with regard to the efficiency of HBOT in various neurological conditions with cognitive disturbance outcome. To the best of our knowledge this is the first state-of-the art, systematic review in the field. More objective and precise neuropsychological assessment methods are needed to exact evaluation of the efficacy of HBOT for neuropsychological deficits. Future studies should widen the assessment of HBOT effects on different cognitive domains because most of the existing studies have focussed on a single process. Finally, there is a need for further longitudinal studies.

Hyperbaric Oxygen Treatment-From Mechanisms to Cognitive Improvement

Hyperbaric oxygen treatment (HBOT)—the medical use of oxygen at environmental pressure greater than one atmosphere absolute—is a very effective therapy for several approved clinical situations, such as carbon monoxide intoxication, incurable diabetes or radiation-injury wounds, and smoke inhalation. In recent years, it has also been used to improve cognition, neuro-wellness, and quality of life following brain trauma and stroke. This opens new avenues for the elderly, including the treatment of neurological and neurodegenerative diseases and improvement of cognition and brain metabolism in cases of mild cognitive impairment. Alongside its integration into clinics, basic research studies have elucidated HBOT’s mechanisms of action and its effects on cellular processes, transcription factors, mitochondrial function, oxidative stress, and inflammation. Therefore, HBOT is becoming a major player in 21st century research and clinical treatments. The following review will discuss the basic mechanisms of HBOT, and its effects on cellular processes, cognition, and brain disorders.

Integrative Role of Hyperbaric Oxygen Therapy on Healthspan, Age-Related Vascular Cognitive Impairment, and Dementia

Growing life expectancy will contribute to the on-going shift towards a world population increasingly comprised of elderly individuals. This demographic shift is associated with a rising prevalence of age-related diseases, among all age-related pathologies it has become crucial to understand the age-associated cognitive changes that remain a major risk factor for the development of vascular cognitive impairment and dementia (VCID). Furthermore, age-related Alzheimer's disease and other neurogenerative diseases with vascular etiology are the most prominent contributing factors for the loss of cognitive function observed in aging. Hyperbaric Oxygen Therapy (HBOT) achieves physiologic effects by increasing oxygen tension (PO2), raising oxygen tissue levels, decreasing intracranial pressure and relieving cerebral edema. Many of the beneficial effects of HBOT exert their protective effects at the level of the microcirculation. Furthermore, the microcirculation's exquisite pervasive presence across every tissue in the body, renders it uniquely able to influence the local environment of most tissues and organs, including the brain. As such, treatments aimed at restoring aging-induced functional and structural alterations of the cerebral microcirculation may potentially contribute to the amelioration of a range of age-related pathologies including vascular cognitive impairment, Alzheimer's disease, and vascular dementias. Despite the presented evidence, the efficacy and safety of HBOT for the treatment of age-related vascular cognitive impairment and dementia remains understudied. The present review aims to examine the existing evidence indicative of a potential therapeutic role for HBOT-induced hyperoxia against age-related cerebromicrovascular pathologies contributing to cognitive impairment, dementia and decreased healthspan in the elderly.

Hyperbaric oxygen therapy improves neurocognitive functions of post-stroke patients - a retrospective analysis

Background:

Previous studies have shown that hyperbaric oxygen therapy (HBOT) can improve the motor functions and memory of post-stroke patients in the chronic stage.

Objective:

The aim of this study is to evaluate the effects of HBOT on overall cognitive functions of post-stroke patients in the chronic stage. The nature, type and location of the stroke were investigated as possible modifiers.

Methods:

A retrospective analysis was conducted on patients who were treated with HBOT for chronic stroke (>3 months) between 2008-2018. Participants were treated in a multi-place hyperbaric chamber with the following protocols: 40 to 60 daily sessions, 5 days per week, each session included 90 min of 100% oxygen at 2 ATA with 5 min air brakes every 20 minutes. Clinically significant improvements (CSI) were defined as > 0.5 standard deviation (SD).

Results:

The study included 162 patients (75.3% males) with a mean age of 60.75±12.91. Of them, 77(47.53%) had cortical strokes, 87(53.7%) strokes were located in the left hemisphere and 121 suffered ischemic strokes (74.6%).

HBOT induced a significant increase in all the cognitive function domains (p < 0.05), with 86% of the stroke victims achieving CSI. There were no significant differences post-HBOT of cortical strokes compared to sub-cortical strokes (p > 0.05). Hemorrhagic strokes had a significantly higher improvement in information processing speed post-HBOT (p < 0.05). Left hemisphere strokes had a higher increase in the motor domain (p < 0.05). In all cognitive domains, the baseline cognitive function was a significant predictor of CSI (p < 0.05), while stroke type, location and side were not significant predictors.

Conclusions:

HBOT induces significant improvements in all cognitive domains even in the late chronic stage. The selection of post-stroke patients for HBOT should be based on functional analysis and baseline cognitive scores rather than the stroke type, location or side of lesion.

Hyperoxygenation revitalizes Alzheimer's disease pathology through the upregulation of neurotrophic factors

Alzheimer’s disease (AD) is a neurodegenerative disease characterized by Aβ‐induced pathology and progressive cognitive decline. The incidence of AD is growing globally, yet a prompt and effective remedy is not available. Aging is the greatest risk factor for AD. Brain aging proceeds with reduced vascularization, which can cause low oxygen (O₂) availability. Accordingly, the question may be raised whether O₂ availability in the brain affects AD pathology. We found that Tg‐APP/PS1 mice treated with 100% O₂ at increased atmospheric pressure in a chamber exhibited markedly reduced Aβ accumulation and hippocampal neuritic atrophy, increased hippocampal neurogenesis, and profoundly improved the cognitive deficits on the multiple behavioral test paradigms. Hyperoxygenation treatment increased the expression of BDNF, NT3, and NT4/5 through the upregulation of MeCP2/p‐CREB activity in HT22 cells in vitro and in the hippocampus of mice. In contrast, siRNA‐mediated inhibition of MeCP2 or TrkB neurotrophin receptors in the hippocampal subregion, which suppresses neurotrophin expression and neurotrophin action, respectively, blocked the therapeutic effects of hyperoxygenation on the cognitive impairments of Tg‐APP/PS1 mice. Our results highlight the importance of the O₂‐related mechanisms in AD pathology, which can be revitalized by hyperoxygenation treatment, and the therapeutic potential of hyperoxygenation for AD.

Hyperbaric oxygen can induce neuroplasticity and improve cognitive functions of patients suffering from anoxic brain damage

Purpose: Cognitive impairment may occur in 42–50% of cardiac arrest survivors. Hyperbaric oxygen therapy (HBO₂) has recently been shown to have neurotherapeutic effects in patients suffering from chronic cognitive impairments (CCI) consequent to stroke and mild traumatic brain injury.

The objective of this study was to assess the neurotherapeutic effect of HBO₂ in patients suffering from CCI due to cardiac arrest.

Methods: Retrospective analysis of patients with CCI caused by cardiac arrest, treated with 60 daily sessions of HBO₂. Evaluation included objective computerized cognitive tests (NeuroTrax), Activity of Daily Living (ADL) and Quality of life questionnaires. The results of these tests were compared with changes in brain activity as assessed by single photon emission computed tomography (SPECT) brain imaging.

Results: The study included 11 cases of CCI patients. Patients were treated with HBO₂, 0.5–7.5 years (mean 2.6 ± 0.6 years) after the cardiac arrest. HBO₂ was found to induce modest, but statistically significant improvement in memory, attention and executive function (mean scores) of 12% , 20% and 24% respectively. The clinical improvements were found to be well correlated with increased brain activity in relevant brain areas as assessed by computerized analysis of the SPECT imaging.

Conclusions: Although further research is needed, the results demonstrate the beneficial effects of HBO₂ on CCI in patients after cardiac arrest, even months to years after the acute event.

Technology Assessment—Impact on Medical Practice

“Technology assessment” is still a relatively new concept, and its application to the field of medicine is even more recent. This results not only from an important effort to develop the scientific basis for health care, but also as a consequence of the growing concern about medical care costs (19). The term refers basically to the evaluation of the costs and effects of a medical technology. The most important methodological approach in this area has been, and still is, the traditional clinical trial, defined by Bradford Hill as “A carefully and ethically designed experiment with the aim of answering some precisely framed question,” including random allocation of the subjects in the trial (4).

The effects of hyperbaric oxygen therapy on oxidative stress, inflammation, and symptoms in children with autism: an open-label pilot study

Background

Recently, hyperbaric oxygen therapy (HBOT) has increased in popularity as a treatment for autism. Numerous studies document oxidative stress and inflammation in individuals with autism; both of these conditions have demonstrated improvement with HBOT, along with enhancement of neurological function and cognitive performance. In this study, children with autism were treated with HBOT at atmospheric pressures and oxygen concentrations in current use for this condition. Changes in markers of oxidative stress and inflammation were measured. The children were evaluated to determine clinical effects and safety.

Methods

Eighteen children with autism, ages 3–16 years, underwent 40 hyperbaric sessions of 45 minutes duration each at either 1.5 atmospheres (atm) and 100% oxygen, or at 1.3 atm and 24% oxygen. Measurements of C-reactive protein (CRP) and markers of oxidative stress, including plasma oxidized glutathione (GSSG), were assessed by fasting blood draws collected before and after the 40 treatments. Changes in clinical symptoms, as rated by parents, were also assessed. The children were closely monitored for potential adverse effects.

Results

At the endpoint of 40 hyperbaric sessions, neither group demonstrated statistically significant changes in mean plasma GSSG levels, indicating intracellular oxidative stress appears unaffected by either regimen. A trend towards improvement in mean CRP was present in both groups; the largest improvements were observed in children with initially higher elevations in CRP. When all 18 children were pooled, a significant improvement in CRP was found (p = 0.021). Pre- and post-parental observations indicated statistically significant improvements in both groups, including motivation, speech, and cognitive awareness (p < 0.05). No major adverse events were observed.

Conclusion

In this prospective pilot study of children with autism, HBOT at a maximum pressure of 1.5 atm with up to 100% oxygen was safe and well tolerated. HBOT did not appreciably worsen oxidative stress and significantly decreased inflammation as measured by CRP levels. Parental observations support anecdotal accounts of improvement in several domains of autism. However, since this was an open-label study, definitive statements regarding the efficacy of HBOT for the treatment of individuals with autism must await results from double-blind, controlled trials.

Trial Registration

clinicaltrials.gov NCT00324909

Ventilatory capacity and risk for dementia

BACKGROUND

Previous studies have found a relationship between single indicators of ventilatory capacity and measures of cognitive function, but have not addressed dementia specifically. This study examined the relationship between different indicators of ventilatory capacity and dementia, diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition, controlling for important confounding factors.

METHODS

Cross-sectional data on participants (n = 437) of the Berlin Aging Study (BASE), which are representative of former West Berlin's living population aged 70 years and older, were analyzed. Ventilatory capacity was measured by spirometry as peak expiratory flow rate (PEF-R), forced expiratory volume in 1 second (FEV-1), maximal expiratory flow at 50% of forced vital capacity (MEF50%FVC), and maximal expiratory flow at 25% of forced vital capacity (MEF25%FVC). Odds ratios (OR) for dementia associated with ventilatory capacity were obtained by logistic regression, adjusting for age, gender, education, ApoE4 status, chronic obstructive pulmonary disease, smoking, heart failure, visual and auditory functioning, grip strength, and former physical activity.

RESULTS

Separate analyses for PEF-R, FEV-1, MEF50%FVC, and MEF25%FVC revealed significantly increased odds for dementia among subjects in the lowest compared with the best functioning group in ventilatory testing. The OR associated with PEF-R > or = 2 l/s was found to be 20.4 (confidence interval [CI] 5.1-82.7). For FEV-1, MEF50%FVC, and MEF25%FVC ORs of 7.5 (CI 2.1-27.9), 4.3 (CI 1.5-12.5), and 4.7 (CI 1.3-17) were obtained, respectively.

CONCLUSIONS

Ventilatory capacity, measured by spirometry in a representative sample of very elderly people, is cross-sectionally related to dementia. Taking evidence from longitudinal studies into account, this result suggests that decreased respiratory function may increase the risk for dementia, independent from already known risk factors.

Effects of a 10-month endurance-training program on performance of speeded perceptual-motor tasks

This study investigated the effects of a 10-mo. endurance-training program (running) on speeded psychometric skills. On a weekly basis the experimental group of 36 subjects participated in one supervised and three unsupervised training sessions. The control group of 22 subjects engaged in no structural training activities during this period. Subjects' performance on a simple reaction-time task, a choice reaction-time task, and a letter-recognition task was assessed before and after the training intervention. Analysis indicated that a 20% improvement in aerobic fitness in the trained group was not accompanied by a significant improvement in psychometric performance. This result is discussed in terms of the relationship between aerobic fitness and cognitive performance. It is concluded that improved physical fitness is not necessarily accompanied by improved perceptual-motor skills.

Acute effects of oxygen treatment upon information processing in hypoxemic COPD patients

The present study investigated the effects of oxygen therapy upon human information processing for hypoxemic COPD patients. Each of ten patients was admitted to a general clinical research center for a two-day period. In a randomly counter-balanced factorial design, patients breathed either room air or enriched oxygen for either six hours or 20 minutes prior to testing. The tests evaluated speed of information processing, ability to detect correct sequence of tones, and serial memory. In addition, patients were evaluated on critical flicker fusion and story recall. The results suggested that acute oxygen therapy does not reverse information processing deficits observed in hypoxemic COPD patients.

The effects of nicotinic acid and xanthinol nicotinate on human memory in different categories of age. A double blind study

The treatment effect of nicotinic acid and xanthinol nicotinate on human memory was compared with placebo in 96 healthy subjects. Forty-three subjects were young (35-45 years), 30 subjects middle aged (55-65 years) and 23 subjects were old aged (75-85 years). Pre- and post-treatment scores were measured on a battery of memory tasks, covering sensory register, short-term memory and long-term memory. The treatment regime was 1 dragee t.i.d. for 8 weeks. The administration of xanthinol nicotinate (500 mg, containing 141.7 mg nicotinic acid), nicotinic acid (141.7 mg) and placebo (lactose) was double-blind. Pre- and post-treatment scores were analysed by means of a multivariate covariance technique, the pre-treatment score serving as covariate. Nicotinic acid treatment resulted in improvement of sensory register and short-term memory, while xanthinol nicotinate improved sensory register, short-term memory and long-term memory. In comparison with placebo, both active compounds yielded improvements of 10-40%, depending on type of task. Treatment effects of nicotinic acid were predominantly found in the young and middle-aged, whereas treatment effects of xanthinol nicotinate were predominantly found in the old. These results are interpreted by the supposed activity of nicotinic acid at the cell membrane, improving neuronal transmission, and of xanthinol nicotinate inside the cell, enhancing cell metabolism and oxygen supply in the brain.

Aerobic exercise training and improved neuropsychological function of older individuals

The effects of a four month aerobic exercise conditioning program on neuropsychological test performance, depression indices, sensory thresholds, and visual acuity of 55-70 year old sedentary individuals were evaluated. Aerobically trained subjects were compared with two age-matched control groups of subjects: those who trained with strength and flexibility exercises and others who were not engaged in a supervised exercise program. The aerobically trained subjects demonstrated significantly greater improvement on the neuropsychological test battery than did either control group. Depression scores, sensory thresholds, and visual acuity were not changed by aerobic exercise. The pattern of results suggests that the effect of aerobic exercise training was on central rather than on peripheral function. We speculate that aerobic exercise promoted increased cerebral metabolic activity with a resultant improvement in neuropsychological test scores.

Neuropsychological deficits among patients with chronic obstructive pulmonary disease

Sixty-six patients with chronic obstructive pulmonary disease (COPD) were evaluated for neuropsychological functioning. While the patients showed normal skills on broad intellectual tasks, they displayed mild cerebral deficits on several neuropsychological tests. Multiple regression analyses revealed that the neuropsychological test battery scores were significantly related to partial pressure of arterial oxygen (PaO2), and to degree of pulmonary impairment. Although the cognitive deficits were real, they were generally small. This result may explain why the widely assumed link between chronic lung disorders and cognitive deficit has been difficult to demonstrate. The general pattern was similar to deficits produced by chronic alcoholism and childhood asthma, with complex skills suffering the greatest insult. Because the cognitive deficits among COPD patients in stable condition are small, it is uncertain whether they have importance clinically or for accomplishing daily activities.

The effect of regular exercise on cognitive functioning and personality

The effect of regular exercise on cognitive functioning and personality was investigated in 32 subjects representing 4 discrete groups based on sex and age. Before and after a 10 week exercise programme of jogging, calisthenics, and recreational activities, a test battery was administered to assess functioning in a number of domains: intelligence (WAIS Digit Symbol and Block Design); brain function (Trail-Making); speed of performance (Crossing-Off); memory and learning (WMS Visual Reproduction and Associate Learning); morale and life satisfaction (Life Satisfaction and Control Ratings); anxiety (MAACL); and depression (MAACL). Improvement was observed on several physiological parameters. ANOVA revealed significant sex and age differences on Digit Symbol and Block Design and age differences on Trail-Making, Crossing-Off, Associate Learning, and anxiety. Regardless of sex and age, significant improvement in performance was observed from pre to post-test on Digit Symbol, Block Design, Trail-Making, Crossing-Off, and on Associate Learning. In addition, an increase on health status rating (p less than .01) and decrease in anxiety were observed from pre to post-test. These data illustrate beneficial effects of exercise on certain measures of cognitive functioning and personality.

Neuropsychologic effects of continuous oxygen therapy in the aged

This study investigated the effects of continuous therapy with oxygen on the neuropsychologic functioning of aged subjects professing problems with their memory. Nineteen men (mean age, 71 years) were evaluated on eight neuropsychologic measures during three different periods of time. Subjects were tested before any treatment, after a month of continuous therapy with oxygen, and after a period of sham treatment. The results indicated statistically significant improvement in the Wechsler Memory Quotient and, with one exception, improvement in all other measurements in favor of the treatment with oxygen. Differences between the results of this investigation and those of other studies are discussed, along with the factors possibly accounting for these differences.

Evaluation of isobaric oxygenation for the aged with cognitive impairment: pilot study

The effect of isobaric oxygenation on psychogeriatric subjects, with mild cognitive impairment was assessed in a single-blind controlled pilot study. Three of the 7 subjects were treated with a mixture of 97% oxygen plus 3% carbon dioxide, and 4 treated with compressed air. The oxygen or air was administered during two 1.5 hr sessions daily for fifteen consecutive days. Use of a miner's type mask ensured a closed system which permits the maximal partial pressure of oxygen. Psychologic and clinical observations did not indicate any advantage for the oxygenation therapy. Minimal side effects, which arose only in the oxygen group, may have involved some interactions between CO2 sensitivity and anxiety. Careful differential diagnosis and the control of motivational factors are of major importance in any study of the effects of oxygenation upon symptoms in psychogeriatric patients.

"Senile dementia": a changing perspective

To demonstrate how 'senile dementia emerged as an important psychiatric concept is not an easy task. Although the history of general psychiatry can be satisfactorily traced to the spirited endeavours of Hippocrates (460–375 B.C.), Celsus (circa 30 a.d.), Soranus the elder (circa 100 a.d.), and Aretaeus (circa 150 a.d.), the psychiatry of old age unfortunately lacks such a clear and well-defined genealogy. The term 'senile dementia’ itself seems to have been first used by Aretaeus, the physician of Cappadocia, but exactly how it had evolved and how it was differentiated, if at all, from normal senescence is not at all clear. Certainly modern psychiatry has inherited a wealth of graphic description of old age in general, and for a detailed account of the relevant ethnographic literature the reader is referred to the excellent article by Rosen (1961). From a scientific point of view, however, it is unfortunate that the spirit of enquiry and the descriptive contributions of the early writers seem to have been tempered more by the degree of optimism or pessimism with which they anticipated the intellectual and behavioural foibles of old age, than by a desire to explore and evaluate systematically its possible deviations.

The effect of hyperbaric oxygen on the mental and verbal ability of stroke patients

Based upon the assumption that oxygen under increased atmospheric pressure (OHP) might improve the verbal and mental function of patients who had suffered vascular infarcts, 32 stroke patients were exposed to such an ambient atmosphere and tested under controlled conditions. The results make it clear that a single exposure to 100% oxygen under two atmospheres of pressure, which is productive of high blood oxygen levels, does not improve the communication and cognitive-perceptual function of these patients.