2009年7月29日水曜日

Anorexia nervosa (& Body dysmorphic disorder ↑ ) 神経性食思不振症(日本語)


Michael's death has some similarities to the death of Karen Carpenter (at 32). She was a known aneorexic and died of a heart failure.
Karen suffered heart failure at her parents' home in Downey, California. She was taken to Downey Community Hospital, where she was pronounced dead twenty minutes later. The LA coroner gave the cause of death as "heartbeat irregularities brought on by chemical imbalances associated with anorexia nervosa."

Too Ugly To Live, Body Dysmorphic Disorder - Part 2


From Wikipedia
Anorexia nervosa is a psychiatric illness that describes an eating disorder characterized by extremely low body weight and body image distortion with an obsessive fear of gaining weight. Individuals with anorexia nervosa are known to control body weight commonly through the means of voluntary starvation, excessive exercise, or other weight control measures such as diet pills or diuretic drugs. While the condition primarily affects adolescent females approximately 10% of people with the diagnosis are male. Anorexia nervosa, involving neurobiological, psychological, and sociological components, is a complex condition that can lead to death in the most severe cases.

"Anorexia nervosa" is frequently shortened to "anorexia" in the popular media. This is technically incorrect, as the term "anorexia" used separately refers to the medical symptom of reduced appetite (which therefore is distinguishable from anorexia nervosa in being non-psychiatric).

-Diagnosis and clinical features-
To be diagnosed as having anorexia nervosa, according to the DSM-IV-TR, a person must display:

1. Refusal to maintain body weight at or above a minimally normal weight for age and height : Weight loss leading to maintenance of body weight <85% of that expected or failure to make expected weight gain during period of growth, leading to body weight less than 85% of that expected.
2. Intense fear of gaining weight or becoming fat, even though under weight.
3. Disturbance in the way in which one's body weight or shape is experienced, undue influence of body weight or shape on self-evaluation, or denial of the seriousness of the current low body weight.
4. The absence of at least three consecutive menstrual cycles (amenorrhea) in women who have had their first menstrual period but have not yet gone through menopause (postmenarcheal, premenopausal females).

Furthermore, the DSM-IV-TR specifies two subtypes:

* Restricting Type: during the current episode of anorexia nervosa, the person has not regularly engaged in binge-eating or purging behavior (that is, self-induced vomiting, or the misuse of laxatives, diuretics, or enemas). Weight loss is accomplished primarily through dieting, fasting, or excessive exercise.
* Binge-Eating Type or Purging Type: during the current episode of anorexia nervosa, the person has regularly engaged in binge-eating OR purging behavior (that is, self-induced vomiting, or the misuse of laxatives, diuretics, or enemas).

The ICD-10 criteria are similar, but in addition, specifically mention

1. The ways that individuals might induce weight-loss or maintain low body weight (avoiding fattening foods, self-induced vomiting, self-induced purging, excessive exercise, excessive use of appetite suppressants or diuretics).
2. Certain physiological features, including "widespread endocrine disorder involving hypothalamic-pituitary-gonadal axis is manifest in women as amenorrhoea and in men as loss of sexual interest and potency. There may also be elevated levels of growth hormones, raised cortisol levels, changes in the peripheral metabolism of thyroid hormone and abnormalities of insulin secretion".
3. If onset is before puberty, that development is delayed or arrested.


There are a number of features that, although not necessarily diagnostic of anorexia, have been found to be commonly (but not exclusively) present in those with this eating disorder.

*Physical
Changes in brain structure and function are early signs often to be associated with starvation, and is partially reversed when normal weight is regained. Anorexia is also linked to reduced blood flow in the temporal lobes, although since this finding does not correlate with current weight, it is possible that it is a risk trait rather than an effect of starvation.

Other effects may include the following:
* Extreme weight loss
* Body mass index less than 17.5 in adults, or 85% of expected weight in children
* Stunted growth
* Endocrine disorder, leading to cessation of periods in females (amenorrhoea)
* Decreased libido; impotence in males
* Reduced metabolism, slow heart rate (bradycardia), hypotension, orthostatic hypotension, hypothermia, inappropriate sinus tachycardia and anemia
* Abnormalities of mineral and electrolyte levels in the body
* Thinning of the hair
* Growth of lanugo hair over the body
* Constantly feeling cold
* Constipation
* Abnormalities of mineral and electrolyte levels
* Zinc deficiency
* Potassium deficiency
* Refeeding syndrome
* Reduction in white blood cell count
* Reduced immune system function
* Pallid complexion and sunken eyes
* Patulous eustachian tube
* Creaking joints and bones
* Osteoporosis
* Collection of fluid in ankles during the day and around eyes during the night or peripheral oedema
* Tooth decay
* Dry skin
* Dry or chapped lips
* Poor circulation (cool peripheries), resulting in common attacks of "pins and needles" (Parathesia) and purple extremities
* In cases of extreme weight loss, there can be nerve deterioration, leading to difficulty in moving the feet
* Headaches
* Brittle fingernails
* Bruising easily
* Fragile appearance
* Slowing of the growth rate of breasts
* Bed sores and wounds that don't heal timely
* Widespread body pain
* Extreme fatigue
* Vertigo, fainting; usually related to low blood pressure
* Difficulty concentrating, memory deficits


* Distorted body image
* Poor insight
* Self-evaluation largely, or even exclusively, in terms of their shape and weight
* Pre-occupation or obsessive thoughts about food and weight
* Perfectionism
* Obsessive compulsive disorder (OCD)
* Belief that control over food/body is synonymous with being in control of one's life
* Refusal to accept that one's weight is dangerously low even when it could be deadly
* Neuropsychological impairment at very low body weights

*Emotional
* Low self-esteem and self-efficacy
* Phobia of becoming overweight
* Clinical depression or chronically low mood
* Mood swings

*Behavioral
* Excessive exercise, food restriction
* Secretive about eating or exercise behavior
* Fainting
* Social withdraw or being asocial
* Self-harm, substance abuse or suicide attempts
* Very sensitive to references about body weight
* Aggressive when forced to eat "forbidden" foods
* Weighing themselves and constantly checking themselves in the mirror

*Diagnostic issues and controversies
The distinction between the diagnoses of anorexia nervosa, bulimia nervosa and eating disorder not otherwise specified (EDNOS) is often difficult to make in practice and there is considerable overlap between patients diagnosed with these conditions. Furthermore, seemingly minor changes in a patient's overall behavior or attitude (such as reported feeling of "control" over any binging behavior) can change a diagnosis from "anorexia: binge-eating type" to bulimia nervosa. It is not unusual for a person with an eating disorder to "move through" various diagnoses as his or her behavior and beliefs change over time.

Additionally, it is important to note that an individual may still suffer from a health- or life-threatening eating disorder (e.g., sub-clinical anorexia nervosa or EDNOS) even if one diagnostic sign or symptom is still present. For example, a substantial number of patients diagnosed with EDNOS meet all criteria for diagnosis of anorexia nervosa, but lack the three consecutive missed menstrual cycles needed for a diagnosis of anorexia.

Feminist writers such as Susie Orbach and Naomi Wolf have criticized the medicalization of extreme dieting and weight-loss as locating the problem within the affected women, rather than in a society that imposes concepts of unreasonable and unhealthy thinness as a measure of female beauty and gaining weight. Other writers have suggested that the disorder relates to issues of self-perception that are deeper than concerns with beauty and public perception.[7]

A vigorous debate exists on the topic of whether eating disorders are a choice or a biological illness. In 2006, Dr. Thomas Insel, director of the US National Institute of Mental Health, wrote an open letter to the National Eating Disorder Association stating "eating disorders are brain disorders."

-Causes and contributory factors-
It is clear that there is no single cause for anorexia and that it stems from a mixture of biological, social, and psychological factors. Current research is commonly focused on explaining existing factors and uncovering new causes. However, there is considerable debate over how much each of the known causes contributes to the development of anorexia. In particular, the contribution of perceived media pressure on women to be thin has been especially contentious.



*Genetic factors
Family and twin studies have suggested that genetic factors contribute to about 50% of the variance for the development of an eating disorder and that anorexia shares a genetic risk with clinical depression. This evidence suggests that genes influencing both eating regulation, and personality and emotion, may be important contributing factors. In one study, variations in the norepinephrine transporter gene promoter were associated with restrictive anorexia nervosa, but not binge-purge anorexia (though the latter may have been due to small sample size).

Several rodent models of anorexia have been developed which largely involve subjecting the animals to various environmental stressors or using gene knockout mice to test hypotheses about the effects of certain genes. These models have suggested that the hypothalamic-pituitary-adrenal axis may be a contributory factor. However, these models have been criticised as food is being limited by the experimenter and not the animal and cannot take into account the complex cultural factors known to affect the development of anorexia nervosa.

*Neurobiological factors
There are strong correlations between the neurotransmitter serotonin and various psychological symptoms such as mood, sleep, emesis (vomiting), sexuality and appetite. A recent review of the scientific literature has suggested that anorexia is linked to a disturbed serotonin system,[13] particularly to high levels at areas in the brain with the 5HT1A receptor - a system particularly linked to anxiety, mood and impulse control. Starvation has been hypothesised to be a response to these effects, as it is known to lower tryptophan and steroid hormone metabolism, which, in turn, might reduce serotonin levels at these critical sites and, hence, ward off anxiety. In contrast, studies of the 5HT2A serotonin receptor (linked to regulation of feeding, mood, and anxiety), suggest that serotonin activity is decreased at these sites. One difficulty with this work is that it is sometimes difficult to separate cause and effect, in that these disturbances to brain neurochemistry may be as much the result of starvation, than continuously existing traits that might predispose someone to develop anorexia. However, there is evidence that both personality characteristics (such as anxiety and perfectionism) and disturbances to the serotonin system are still apparent after patients have recovered from anorexia. This suggests that these disturbances are likely to be causal risk factors.

Recent studies also suggest anorexia may be linked to an autoimmune response to melanocortin peptides which influence appetite and stress responses.

*Nutritional factors
Zinc deficiency causes a decrease in appetite that can degenerate in anorexia nervosa (AN), appetite disorders and, notably, inadequate zinc nutriture. The use of zinc in the treatment of anorexia nervosa has been advocated since 1979 by Bakan. At least five trials showed that zinc improved weight gain in anorexia. A 1994 randomized, double-blind, placebo-controlled trial showed that zinc (14 mg per day) doubled the rate of body mass increase in the treatment of AN. Deficiency of other nutrients such as tyrosine and tryptophan (precursors of the monoamine neurotransmitters norepinephrine and serotonin, respectively), as well as vitamin B1 (thiamine) could contribute to this phenomenon of malnutrition-induced malnutrition.

-Psychological factors-
There has been a significant amount of study on psychological factors that suggests how biases in thinking and perception help maintain or contribute to the risk of developing anorexia.

Anorexic eating behavior is thought to originate from feelings of fatness and unattractiveness[17] and is maintained by various cognitive biases that alter how the affected individual evaluates and thinks about their body, food and eating.

One of the most well-known findings is that people with anorexia tend to over-estimate the size or fatness of their own bodies. A recent review of research in this area suggests that this is not a perceptual problem, but one of how the perceptual information is evaluated by the affected person. Recent research suggests people with anorexia nervosa may lack a type of overconfidence bias in which the majority of people feel themselves more attractive than others would rate them. In contrast, people with anorexia nervosa seem to more accurately judge their own attractiveness compared to unaffected people, meaning that they potentially lack this self-esteem boosting bias.

People with anorexia have been found to have certain personality traits that are thought to predispose them to develop eating disorders. High levels of obsession (being subject to intrusive thoughts about food and weight-related issues), restraint (being able to fight temptation), and clinical levels of perfectionism (the pathological pursuit of personal high-standards and the need for control) have been cited as commonly reported factors in research studies.

It is often the case that other psychological difficulties and mental illnesses exist alongside anorexia nervosa in the sufferer. Clinical depression, obsessive compulsive disorder, substance abuse and one or more personality disorders are the most likely conditions to be comorbid with anorexia, and high-levels of anxiety and depression are likely to be present regardless of whether they fulfill diagnostic criteria for a specific syndrome.

Research into the neuropsychology of anorexia has indicated that many of the findings are inconsistent across studies and that it is hard to differentiate the effects of starvation on the brain from any long-standing characteristics. Nevertheless, one reasonably reliable finding is that those with anorexia have poor cognitive flexibility (the ability to change past patterns of thinking, particularly linked to the function of the frontal lobes and executive system).

Other studies have suggested that there are some attention and memory biases that may maintain anorexia. Attentional biases seem to focus particularly on body and body-shape related concepts, making them more salient for those affected by the condition, and some limited studies have found that those with anorexia may be more likely to recall related material than unrelated material.
Fairburn and colleagues psychological model of anorexia

Although there has been quite a lot of research into psychological factors, there are relatively few hypotheses which attempt to explain the condition as a whole.

Professor Chris Fairburn, of the University of Oxford and his colleagues have created a "transdiagnostic" model, in which they aim to explain how anorexia, as well as related disorders such as bulimia nervosa and ED-NOS, are maintained. Their model is developed with psychological therapies, particularly cognitive behavioral therapy, in mind, and so suggests areas where clinicians could provide psychological treatment.

Their model is based on the idea that all major eating disorders (with the exception of obesity) share some core types of psychopathology which help maintain the eating disorder behavior. This includes clinical perfectionism, chronic low self-esteem, mood intolerance (inability to cope appropriately with certain emotional states) and interpersonal difficulties.

*Social and environmental factors
Sociocultural studies have highlighted the role of cultural factors, such as the promotion of thinness as the ideal female form in Western industrialised nations, particularly through the media. A recent epidemiological study of 989,871 Swedish residents indicated that gender, ethnicity and socio-economic status were large influences on the chance of developing anorexia, with those with non-European parents among the least likely to be diagnosed with the condition, and those in wealthy, white families being most at risk. A classic study by Garner and Garfinkel demonstrated that those in professions where there is a particular social pressure to be thin (such as models and dancers) were much more likely to develop anorexia during the course of their career, and further research has suggested that those with anorexia have much higher contact with cultural sources that promote weight-loss.

Although anorexia nervosa is usually associated with Western cultures, exposure to Western media is thought to have led to an increase in cases in non-Western countries. However, it is notable that other cultures may not display the same "fat phobic" worries about becoming fat as those with the condition in the West, and instead may present with low appetite with the other common features.

There is a high rate of reported child sexual abuse experiences in clinical groups of who have been diagnosed with anorexia (up to 50% in those admitted to inpatient wards, with a lesser prevalence among people treated in the community). Although prior sexual abuse is not thought to be a specific risk factor for anorexia, those who have experienced such abuse are more likely to have more serious and chronic symptoms.

The Internet has enabled anorexics and bulimics to contact and communicate with each other outside of a treatment environment, with much lower risks of rejection by mainstream society. A variety of websites exist, some run by sufferers, some by former sufferers, and some by professionals. The majority of such sites support a medical view of anorexia as a disorder to be cured, although some people affected by anorexia have formed online pro-ana communities that reject the medical view and argue that anorexia is a "lifestyle choice", using the internet for mutual support, and to swap weight-loss tips.[30] Such websites were the subject of significant media interest, largely focusing on concerns that these communities could encourage young women to develop or maintain eating disorders, and many were taken offline as a result.

-Prognosis-
Anorexia is thought to have the highest mortality rate of any psychiatric disorder, with approximately 6% of those who are diagnosed with the disorder eventually die due to related causes. The suicide rate of people with anorexia is also higher than that of the general population and is thought to be the major cause of death for those with the condition.

-Incidence, prevalence and demographics-
The majority of research into the incidence and prevalence of anorexia has been done in Western industrialized countries, so results are generally not applicable outside these areas. However, recent reviews[34][35] of studies on the epidemiology of anorexia have suggested an incidence of between 8 and 13 cases per 100,000 persons per year and an average prevalence of 0.3% using strict criteria for diagnosis. These studies also confirm the view that the condition largely affects young adolescent females, with females between 15 and 19 years old making up 40% of all cases. Furthermore, the majority of cases are unlikely to be in contact with mental health services. As a whole, about 10% of people with anorexia are male and about 90% of people with anorexia are female. Anorexia, however, is not exclusively limited to any age or demographic. In March 2008, a British senior university lecturer with PhD in psychology and a professional background in health, Rosemary Pope, died from anorexia. Anorexia has been reported occurring throughout a patient's life extending into the seventies and eighties. In addition, onset can occur in one's sixties or later. The Italian character actor, Giovanni Rovini, died of onset of symptoms commencing in his early nineties.

神経性無食欲症(しんけいせいむしょくよくしょう、anorexia nervosa: AN)は精神疾患のうち、摂食障害の一種である。一般には拒食症(きょしょくしょう)とも言われる。若年層に好発し、ボディ・イメージの障害(「自分は太っている」と考えること)、食物摂取の不良または拒否、体重減少を特徴とする。神経性食欲不振症、神経性食思不振症、思春期やせ症とも言う。

総論

神経性無食欲症は、心理的要因・社会的要因・生物学的要因によって生じる、摂食行動を主な表現形とする精神疾患である。特に、心理的要因(ストレス)によるところが多く、慢性経過をとることが多い。近年、日本において増加傾向にあり、また経過途中で抑うつを伴ったり身体的疾患を合併することもあり、社会に与える影響も大きい。

典型的なANの患者では、体重を落とすために始めたダイエットで達成感が得られ、体重を落とすことを止められなくなってしまう。低体重であっても自分の体重を多すぎると感じ、さらに体重を減らすことを望む。鏡を見ても「まだまだ痩せられる」と感じるのみであり、体重が低すぎるとは考えない。

宗教上の理由から断食をする場合、政治的目的から断食によるストライキを行う場合、あるいはカロリーを制限することで長寿が達成できるという健康上の信念を持っている場合に、食事を摂らないか極端に食事の摂取量を減らす例があるが、これらはANではない。

時にANは、神経性大食症(過食症)や、その他非定型性の摂食障害へと、病像が変化する場合がある。

疫学

社会的要素を含む疾患であるため、その病態は国によっても異なる。ダイエットが若年層の一大関心事である日本におけるANは、若年層、特に青年期の女性に非常に多いことが特徴である。若年男性でのANの発症も見られることがあるが、男女比はおよそ1対20である。発症年齢が年々低年齢化しており、小学生での発症も増加している。治療は一般に困難であり、長い時間がかかる。合併症や自殺のために経過の途中で死亡する例もある(5%~15%程度)。

一方で、近代的なダイエットとは無縁のアフリカの地方部においてAN様の病像を呈する症例の報告があり、宗教的信念との関連が考えられている。

歴史

日本において、ANが昔から精神の病として存在したことは、文学作品である『源氏物語』に窺い知ることができる。『源氏物語』第三部の宇治十帖で夭折する宇治の大君は、没落した宮家の姫君であり、経済的基盤のある身内がいない。大君の父の宇治八の宮は主人公の薫に娘である二人の姫君の後見(結婚のこと)を託して死亡する。結婚したくない大君は代わりに妹の中君を薫に娶せようとするが、中君は次の東宮と目される匂宮と結婚してしまう。しかし、正妻になる社会的地位を有さない中君と匂宮との結婚生活が苦渋に満ちたものであると思い込んだ大君は、自分が薫と結婚しても同じことになると悟り、ANに罹って衰弱死するのである。(出典:「源氏物語」紫式部)

症状

ANは、精神神経疾患の中では、致死率が最も高い疾患のなかのひとつであり、最終的な致死率は5%-20%程度である。主な死因は、極度の低栄養による感染症や不整脈の併発である。患者は自己の体重が減少することに満足できるため、自殺が死因となることは神経性大食症(過食症)と比較して少ないが、 抑うつ症状を伴うこともあり、自殺企図をきたす症例もある。

* 極度の体重減少
* 女性の場合、無月経
* 活動性の上昇、易興奮性、睡眠障害
* 抑うつ症状
* 食物への興味の上昇…しばしば料理関係の情報を収集する
* 強迫的な思考
* 自傷行為
* 手掌・足底の黄染(高カロテン血症)
* 低血圧
* 低体温
* 徐脈
* 便秘、腹痛
* 電解質代謝異常、特に低カリウム血症
* 骨粗鬆症
* 続発性甲状腺機能低下症
* 色素性痒疹…胸や肩などの痒みの強い発疹が出現する皮膚疾患

電解質代謝異常は、特に利尿剤の乱用が見られる症例では起こりやすく、時に低カリウム血症から致死性の不整脈をきたし、急激に死に至ることがある。

また、これらの個人に属する症状に加えて、極度の体重減少や易刺激性が、周囲との関係不良をもたらすことも大きな問題となる。

診断

DSM-IVの診断基準では、「標準体重の85%の値を維持することを拒否する」「体重が減少しているときでも、現在の体重が増加することに対して恐怖がある」「標準体重に満たない場合も、自分自身の体重を多すぎると感じる」「(初潮後の女性の場合)3周期以上に渡る無月経」の4項目を診断基準としている。

さらに、

* 活動性の亢進があること。体重を落とすため、必要以上の運動・活動を行うこと。
* 現在の病状、深刻性について、認識に乏しいこと。

を組み合わせて診断を行う。診断基準に完全には合致しない場合に、非定型摂食障害(特定不能の摂食障害)の診断になることがある。例えば月経が不順ながら存在し、その他はANの基準を満たす場合、非定型摂食障害と診断される。

摂食障害の患者は時に診療を拒否し、問診の際に症状を隠す傾向にあるため注意が必要。

ANは、以下の2種類のサブタイプに分類される。

* 制限型神経性無食欲症(AN-R)

制限型のAN(restricting type)では、食物を口にすることを重度に制限するが、AN-BPに見られるような行動は行ったことがない。

* 無茶食い-排泄型神経性無食欲症(AN-BP)

無茶食い-排泄型のAN(binge-eating/purging type)では、食物を過量に摂取した後、自分で嘔吐を誘発して、あるいは利尿剤、下剤等を用いて、食物の排泄を試みる、というエピソードを行う。(しかし、下剤や利尿剤では食物の吸収をほとんど妨げることはできない。)排泄する代わりに、無茶食いの後に数日間絶食する場合もある。

2002年の「DSM-IV-TR」の診断基準も同様である。

その他の診断基準として、厚生労働省の診断基準やICD-10の診断基準も存在する。

原因

ANの発生原因については議論があるが、生物学的要因・心理的要因・社会的要因の3つの要素があると考える人が多い。

* 生物学的要因についても様々な研究が報告されている。器質的な脳の病変の存在は明らかにされていないが、二卵性双生児よりも一卵性双生児の方が一致率が高いこと、AN患者の家族にはうつ病、アルコール依存、強迫性障害や摂食障害が多いことから遺伝的要因の関与も考えられている。ANの発病に関連する遺伝子もいくつか見いだされてはいるが、結論は出ていない。視床下部におけるドパミン、ノルアドレナリン活性の異常を指摘する研究もある。出産時の合併症(頭蓋内出血、低体重など)がANの罹患率を増加させるという疫学的研究もある[1]。

* 心理的要因が発病に影響しているのは明らかであり、ANの発病前には、発病に関連する何らかのエピソードが見出されるのが通常である。海外の研究において、摂食障害の患者は健常者よりも高い確率で幼少期に性的虐待を含む虐待を受けた経験をもつという報告もあるが、他の精神疾患においても高い確率で性的虐待の既往が報告されており、摂食障害と性的虐待を直接的な因果関係は不明である[2]。またかつて、1970年代などの初期の研究において、高学歴や家庭の経済状態がよいことなどがANの罹患率と相関するという報告がなされ広く信じられていたが、その後の研究ではこの説を支持しないか、むしろ逆の結果が示されることもある[3]。その他にも精神力動学的に様々な考察がなされている。
o 性的な成熟に対する恐怖・女性であることの否定:女性は第二次性徴を迎えると、皮下脂肪をたくわえ身体が丸みを帯び、乳房がふくらむなど身体が変化する。これらの身体変化に伴い、男性の性的関心の対象となるのを嫌悪・拒絶する心理からANを発症する場合もある。
o 肥満恐怖:肥満への恐怖・嫌悪が存在することが多い。「太っている」などとからかわれることが発症のきっかけとなる場合も多い。また女性の場合、第二次性徴によって皮下脂肪の蓄積するため、前述の性的成熟拒否と肥満恐怖が混合している場合も多い。
o 母親となることの拒絶:摂食拒否によって母親になることを拒絶しているという説。
o 対人関係の障害:原因なのか結果なのかは不明であるが、対人関係に障害を有する症例が多い。
o 失感情症(アレキシサイミア):自らの感情に気づくことができない・できにくいことを「失感情症(アレキシサイミア)」という。ANも失感情症の要素があることが指摘されており、自らのストレスやつらい気持ちに気づかず(否認して)、その代わり身体症状で表現しているという可能性がある。
o 完璧主義・強迫性も、AN患者においてしばしばみられる。
o 嗜癖(依存症)としての要素:ANの初期に、摂食量を制限して体重が減るという結果を得て満足し、更に摂食量制限にふけり、独特の気分高揚を示すことがある。この心性は薬物依存やギャンブル依存などの嗜癖行動との共通点があると言われている。

* 社会的要因もANの発症に関与している。
o メディアにおいてやせた女性、元気で快活な女性が賞賛され、内面よりも外見を重視するような風潮は、ANの発症の大きな要因であろう。実際に、 12~21歳の2862人の思春期少女を18か月間追跡調査したところ、90人が摂食障害を新たに発症したが、発症に関与した因子として一人で食事をすること、少女雑誌をよく読むことやラジオをよく聴くことが挙げられた[4]という研究もあり、メディアの影響がうかがわれる。
o 芸能界やモデル業界などの美を競う業界や、痩せていることが重要だと考えられているスポーツ選手においてANにかかる患者がいることが注目を集めている。

2006年現在、当疾患および神経性過食症をあわせた「中枢性摂食異常症」は厚生労働省の特定疾患に該当し、重点的に研究が進められている。

治療

他の精神疾患がそうであるように、ANも社会的・精神的・肉体的な要素を併せ持つ複雑な疾患である。早期の治療は治療の成功率を高める。

治療法は、入院・外来での疾患教育、認知行動療法や集団療法などの心理療法、薬物療法、家族のカウンセリングなどが中心となる。患者が病気であることを否認する場合や、ANの存在を容認したとしても治療には拒否の姿勢を示す場合はよくみられる。さらには、治療を認める姿勢を見せて、実際には出された食事を隠れて捨てる、などの行為も少なからず見られる。

治療にあたっては、体重増加のみを治療目的とすべきではない。「とにかく食べろ」といった強硬な姿勢を家族や治療者が見せることは、通常逆効果となる。長い間ANと戦っている患者にとって、食物を食べること自体が大変な苦痛・恐怖につながるためである。また体重増加以外にも、患者の主体性を重視し、人間としての成熟、対人関係の充実、実生活での適応などを援助することが重要だからである。以上のように、適切な医師-患者関係、家族-患者関係を築くことが最も大切である。

インターネット等で摂食障害患者、元患者との交流を持つことがよい影響をもたらす場合もある。

治療により軽快した場合、再発や、神経性大食症の発症に注意する必要がある。

厚生労働省の特定疾患に該当し(前述)、治療法についても重点的に研究が進められている。

参考

* オーストリアのエリーザベト皇后も、嫁姑問題を契機にANを発症したといわれている。
* 日本では、ANは一般的には「拒食症」の名前で知られており、その患者の実態は、たびたびドキュメンタリーとしてマスコミに取り上げられることがある。カーペンターズのカレン・カーペンターが拒食症から心臓発作を起こして死亡した際に、本症は日本やアメリカで大きな注目を浴び、注目される疾患となった。
* 東電OL殺人事件の被害者女性も慶應義塾大学を卒業し総合職として東京電力に入社した30代独身のエリート社員であったが、セックス依存症の性癖とANの双方を発症していた。

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