乾燥した高温の風と大気イオンとセロトニン
人間に対する大気イオンの影響について、まとまった形で研究を行ったのは、イスラエルのFG Sulmanの研究チームである。これは1970年代から1980年代にかけて行われたもので、主として、Sharavと呼ばれる乾燥・高温な砂漠の風による"Serotonin Irritation Syndrome"を対象としている。FG Sulmanは、その抑制方法として、3.5x105/cm3程度の陰イオンを室内に満たす方法を考えていた。
M. Assael, Y. Pfeifer and F. G. Sulman: "Influence of artificial air ionisation on the human electroencephalogram", Int. J. Biometeor, 18, 306-312, 1974.この研究は1980年代半ばまで続けられたが、その後は消えている。
Abstract Exposure of 20 subjects to negative ionisation was monitored by EEG. Negative ionisation was supplied by an Ionotron apparatus (Amcor-Amron, Herzlia-Israel) with an output of 3.5 × 105 ions/(cm3 · sec) at 1 m distance. Objective findings in ten normal subjects showed reduction of the frequency of the alpha-waves from 10 or 11 down to 9 or 8 Hz, increase of the amplitude by up to 20%, advance of the alpha rhythm pattern from the occipital to the frontal area and general synchronisation of the EEG records of both hemispheres. These reactions were suppressed in 10 subjects by tranquillisers. Subjective findings included relaxation, alertness, improved working capacity and relief from the Serotonin Irritation Syndrome produced by the positive ionisation of hot, dry desert winds.
F. G. Sulman, D. Levy, A. Levy, Y. Pfeifer, E. Superstine and E. Tal: "Air-ionometry of hot, dry dessert winds(Sharav) and treatment with air ions of weather-sensitive subjects", Int. J. Biometeor., 18, 313-318, 1974
Abstract Hot dry winds (Sharav) produce increased ionisation of the atmosphere, values for positive and negative ions going up from an average of 1, 000 per cm3 to 1, 500. There was almost always a slight preponderance of the positively-charged small ions. This increased air ionisation induces serotonin release in about one-quarter of the population with multiple complaints of a typical serotonin irritation syndrome. In 75% of 129 subjects suffering from serotonin ailments, the treatment with negative air ions (Ionotron) with an output of 3.5 × 105 ions/(cm3 · sec) at 1 m distance produced prophylactic and therapeutic relief when the patients were kept in a room of up to 4 × 4 m size. These results were controlled by serotonin and 5-HIAA urinalysis.
非常に乾燥した風であるカリフォルニア州南部のSanta Ana windについて、同様の研究をOhio State UniversityのAJ Gianniniが1980年代に行っている。AJ Gianniniによれば、このSanta Ana windは不安や焦燥などの精神的影響があり[1]、その原因は体内のセロトニンの増加によるもの[2]である。メカニズムは明らかではないが、AJ Gianniniは、CO2陽イオンがセロトニン分解を抑制している[3]のではないかと考えている。この陽イオンの影響は室内の陰イオンの濃度を上げることで緩和できた[4]という。
[1]Giannini AJ, Malone DA, Piotrowski TA.: "The serotonin irritation syndrome--a new clinical entity?", J Clin Psychiatry. 1986 Jan;47(1):22-5.ただし、以上にもあるように"Serotonin irritation syndrome"の実在を証明するまでには至っていない。そして、その後は、"Serotonin irritation syndrome"というキーワードでの研究はフェードアウトしている。
The literature on the possible existence of a "serotonin irritation syndrome" is examined. This syndrome is an anxiety state occurring in the presence of elevated levels of atmospheric or ambient cations and is associated with elevated central and peripheral serotonin levels. Investigation of these cations' effects on microbes, insects, and mammals, including humans, shows a disruption of normal activity. It is suggested that clinicians become acquainted with the potential relationship between cation exposure and serotonin in their treatment of anxious patients. Further research exploring the etiology and diagnostic definition of this entity is urged.
[2]Giannini AJ, Castellani S, Dvoredsky AE.: "Anxiety states: relationship to atmospheric cations and serotonin.", J Clin Psychiatry. 1983 Jul;44(7):262-4.
Five cases are described that offer evidence for the existence of the "serotonin irritation syndrome," an anxiety state associated with high cation environments, elevated serum serotonin, and decreased urinary 5-hydroxyindoleacetic acid. The therapeutic response and reduction in serum serotonin after treatment with methysergide and/or removal from the high-cation environment support a serotonergic basis of the anxiety.
[3]Giannini AJ.: "Serotonin irritation syndrome: an hypothesis.", Int J Psychiatry Med. 1978-1979;9(2):199-204.
Two patients were seen with multisystememic complaints and anxious feelings. Their history was similar for chronic exposure to potentially ionized atmospheric environments--a waterfall and high-voltage equipment. Physical examination showed various signs sometimes associated with hyperserotonergic states. Laboratory testing showed increased levels of serum serotonin and decreased levels of its metabolite, urinary 5-hydroxyindoleacetic acid (5-HIAA). Removal of the patients from these environments or the use of a serotonin-blocker ameliorated all symptoms and reestablished normal serotonin and 5-HIAA levels. A literature-review disclosed a similar symptom-complex reported with air-ionization during the sweep of hot winds across desert lands. Animal studies are cited in which cation aerosols are used to block serotonin metabolism, producing clinical and laboratory results some of which are similar to those seen in the patients described. It is suggested that a "serotonin irritation syndrome" might be related to cation-induced serotonin metabolic dysfunctions.
[4]Giannini AJ, Jones BT, Loiselle RH.: "Reversibility of serotonin irritation syndrome with atmospheric anions.", J Clin Psychiatry. 1986 Mar;47(3):141-3.
Clinical reports and animal studies support the existence of a "serotonin irritation syndrome." This is a putative anxiety state caused by a rise in atmospheric cations and reversed by a corresponding rise in anions. Volunteers were exposed to generated ambient cations and anions under controlled conditions. Cations were found to increase anxiety, excitement, and suspicion. Anions reversed the effects of cations and, in addition, reduced suspicion and excitement to levels below those occurring before cationization. Implications of these findings and the possible mediation of effects by serotonin are discussed.
また、もし本当に大気イオンによるセロトニンレベルの増大による"Serotonin irritation syndrome"が問題だとしても、選択的セロトニン再取り込み阻害薬があるため、「陰イオンでカウンターする」ことが有効かどうかは別問題。
SADと照明と大気イオン
一方、1990年代後半からはColumbia University のTerman教授のグループによるSAD(季節性情動障害)に対する照明および大気イオンの効果の研究がある。主たるターゲットは、強い照明でフェイクな夜明けを作ることで、SADを治療しようというものだった。その過程で、室内空気中の陰イオンにも治療効果がありそうだという結果を得ている[5,6,7]。
[5]Michael Terman, Ph.D., and Jiuan Su Terman, Ph.D.: "Controlled Trial of Naturalistic Dawn Simulation and Negative Air Ionization for Seasonal Affective Disorder", Am J Psychiatry 163:2126-2133, December 2006強い照明は既に治療に使われているが、もしかすると、陰イオンも治療に用いられることになるかもしれない。ただし、106/cm3と物量が大きく、市販のイオン製造装置の多くは物量不足であるが。
OBJECTIVE: This trial assessed two novel nonpharmaceutical treatments for winter depression―naturalistic dawn simulation and high-density negative air ionization―delivered during the final hours of sleep. METHOD: The patients were 99 adults (77 women and 22 men) with the winter seasonal pattern of major depressive disorder (94 cases) and bipolar II disorder (five cases). Five parallel groups received 1) dawn simulation (0.0003–250 lux in the pattern of May 5 at 45° north latitude); 2) a dawn light pulse (13 minutes, 250 lux, with an illuminant dose of 3.25x103 lux-minutes matched to the simulated dawn); 3) postawakening bright light (30 minutes, 10,000 lux); 4) negative air ionization at high flow rate (93 minutes, 4.5x1014 ions/second); or 5) ionization at low flow rate (93 minutes, 1.7x1011 ions/second). The symptoms were assessed over 3 weeks with the Structured Interview Guide for the Hamilton Depression Rating Scale―Seasonal Affective Disorder Version. RESULTS: Posttreatment improvement results were bright light, 57.1%; dawn simulation, 49.5%; dawn pulse, 42.7%; high-density ions, 47.9%; and low-density ions, 22.7% (significantly lower than the others). Contrary to the authors’ hypothesis, analysis of variance failed to find superiority of dawn simulation to the dawn pulse or bright light. However, the dawn pulse led to a pattern of residual or exacerbated depressive symptoms similar to those seen in low-density ion nonresponders. CONCLUSIONS: Naturalistic dawn simulation and high-density ionization are active antidepressants that do not require the effort of postawakening bright light therapy. They can be considered candidate alternatives to bright light or medication.
[6] Michael Terman, PhD; Jiuan Su Terman, PhD; Donald C. Ross, PhD : "A Controlled Trial of Timed Bright Light and Negative Air Ionization for Treatment of Winter Depression", Arch Gen Psychiatry. 1998;55:875-882.
Background Artificial bright light presents a promising nonpharmacological treatment for seasonal affective disorder. Past studies, however, have lacked adequate placebo controls or sufficient power to detect group differences. The importance of time of day of treatment―specifically, morning light superiority―has remained controversial.
Methods This study used a morningxevening light crossover design balanced by parallel-group controls, in addition to a nonphotic control, negative air ionization. Subjects with seasonal affective disorder (N=158) were randomly assigned to 6 groups for 2 consecutive treatment periods, each 10 to 14 days. Light treatment sequences were morning-evening, evening-morning, morning-morning, and evening-evening (10000 lux, 30 min/d). Ion density was 2.7x106 (high) or 1.0x104 (low) ions per cubic centimeter (high-high and low-low sequences, 30 min/d in the morning).
Results Analysis of depression scale percentage change scores showed low-density ion response to be inferior to all other groups, with no other group differences. Response to evening light was reduced when preceded by treatment with morning light, the sole sequence effect. Stringent remission criteria, however, showed significantly higher response to morning than evening light, regardless of treatment sequence.
Conclusions Bright light and high-density negative air ionization both appear to act as specific antidepressants in patients with seasonal affective disorder. Whether clinical improvement would be further enhanced by their use in combination, or as adjuvants to medication, awaits investigation.
[7]Terman M, Terman JS.: "Treatment of seasonal affective disorder with a high-output negative ionizer.", J Altern Complement Med. 1995 Jan;1(1):87-92.
This study was designed to evaluate the antidepressant effect of negative ions in the ambient air as a potential treatment modality for seasonal affective disorder. Twenty-five subjects with winter depression underwent a double-blind controlled trial of negative ions at two exposure densities, 1 x 10(4) ions/cm3 or 2.7 x 10(6) ions/cm3, using an electronic negative ion generator with wire corona emitters. Home treatments were taken in the early morning for 30 min over 20 days, followed by withdrawals. The severity of depressive symptoms (prominently including the reverse neurovegetative symptoms of hypersomnia, hyperphagia, and fatigability) decreased selectively for the group receiving high-density treatment. Standard depression rating scale assessments were corroborated by clinical impressions. When a remission criterion of 50% or greater reduction in symptom frequency/severity was used, 58% of subjects responded to high-density treatment while 15% responded to low-density treatment (chi 2 = 5.00, df = 1, p = 0.025). There were no side effects attributable to the treatment, and all subjects who responded showed subsequent relapse during withdrawal. Treatment with a high-density negative ionizer appears to act as a specific antidepressant for patients with seasonal affective disorder. The method may be useful as an alternative or supplement to light therapy and medications.
