Groiue

作者：Pauline Anderson  
出處：WebMD醫學新聞

　　March 4, 2010 —一篇新的統合分析發現，肥胖和憂鬱之間有密切關聯，會增加彼此的風險。
　　
　　研究發現，肥胖者發生憂鬱症的風險增加了55%，憂鬱症患者隨著時間變成過重的風險增加58%。
　　
　　第一作者、荷蘭Leiden大學醫學中心的Floriana S. Luppino醫師表示，這些結果將刺激各醫療專科合作，以努力預防憂鬱和肥胖，這些狀況都對健康問題有重大影響。
　　
　　第一步驟是，根據我們所知道的事實盡我們所能，精神科醫師必須監督病患的體重，內科醫師或一般開業醫師應檢視肥胖或過重病患的心情狀態，看他們是否正發生一些大多可以治療的心情疾患。
　　
　　這項研究登載於3月份的一般精神醫學誌(Archives of General Psychiatry)。
　　
　　研究者蒐集以英文發表的文獻進行分析，期限至2008年3月止。這些研究必須是追蹤期間至少1年、使用身體質量指數(BMI)代表體重、載明評量憂鬱症的方式，最後共納入15篇研究進行分析。
　　
　　分析目標為檢視過重(定義為BMI介於25-29.99)或肥胖(定義為BMI大於等於30)與憂鬱之間的關聯，研究對象總數為55,387人，反向分析對象有7,196人，部分研究提供有雙向的縱向資料。
　　
　　對於檢視開始時的肥胖和追蹤時的憂鬱之關聯的8篇研究，彙整的勝算比(OR)為1.55 (95%信心區間[CI]為1.22 – 1.98；P < .001)。
　　
　　【美國的肥胖和憂鬱的關聯更強烈？】
　　美國研究的勝算比和歐洲的研究結果有明顯不同(P = .05)，意味著美國人的此一關聯更強烈，原因還不清楚，不過，根據世界衛生組織指出，美國成人的平均BMI高於歐洲，Luppino醫師表示，如果美國的平均BMI較高，且較高的BMI代表較多憂鬱症，就可以加以解釋。
　　
　　將憂鬱結果視為臨床診斷和視為憂鬱症狀之間的勝算比也有顯著差異(P = .05)，這表示，將憂鬱視為診斷上的臨床訪視加以評量時，此關聯比將其視為自我報告的症狀時更強烈。
　　
　　至於反過來探討憂鬱引起肥胖的關聯時，檢視憂鬱對肥胖之影響的9篇研究，其彙整勝算比為1.58 (95% CI，1.33 – 1.87；P < .001)，次組分析並未顯示有任何顯著差異。
　　
　　憂鬱對過重影響的彙整勝算比為1.20 (95% CI，0.87 – 1.66；P = .26)，次組分析發現，追蹤期間越長時，此關聯越強烈。
　　
　　Luppino醫師表示，相較於憂鬱和過重之間的關聯，憂鬱和肥胖之間的關聯更強烈，認為此關聯之間存有「劑量-反應」關係。
　　
　　【精神科醫師應監測病患體重】
　　Luppino醫師表示，這些新資料認為，精神科醫師應定期監測憂鬱病患的體重，沒錯，就是這麼簡單。
　　
　　如果你認為病患處於過重或肥胖的邊緣，或許，可以進行一些介入方式，例如轉介病患給營養師、或相關的內科醫師或一般開業醫師，這有助於病患控制體重，甚至可藉由改變生活型態或飲食來預防體重增加。
　　
　　雖然之前的研究認為，只有女性才有憂鬱和過重之間的關聯，本次研究確認男性也有。
　　
　　納入分析的研究中，追蹤期間相對較久的研究可以用來提出一個可能的解釋。
　　
　　Luppino醫師表示，在短期間，男女之間的荷爾蒙差異可以解釋何以女性比較可能會過重或肥胖，但是隨著時間增加，其他機轉也會有所影響，最後，這可以解釋兩性的憂鬱病患都有肥胖或過重風險。
　　
　　她表示，憂鬱和肥胖之間的關聯可能有多種因素，不是只有生物或心理路徑，可能是兩者皆有。
　　
　　生物路徑可能包括發炎(與憂鬱和肥胖有關)，下視丘-腦垂腺-腎上腺軸(和兩種狀況都有關聯)、和/或胰島素阻抗性(肥胖增加了糖尿病和胰島素阻抗性的風險，會引起腦部的變化，增加了憂鬱風險)。
　　
　　【強調纖瘦】
　　Luppino醫師表示，一個心理路徑可能是源自西方世界強調纖瘦，體重增加導致自尊降低，而這是憂鬱的一個風險因素。
　　
　　每個人的肥胖和憂鬱的關聯本質是不同的，某個人可能是因為生物系統沒有正常運作，另一個人可能是因為自尊低，當他變得肥胖時，這可能是讓他發生憂鬱的臨門一腳。
　　
　　但是，或許生物路徑和心理路徑這兩者都要有才會造成肥胖和憂鬱的關聯，Luppino醫師表示，如果一個人因為生物因素變肥胖或過重，但是依舊有強烈自尊感，對自己的身體也沒有感到不滿意，那就不會發生憂鬱。
　　
　　Luppino醫師表示，增加憂鬱發生的基因也有所影響，對於一個有良好自尊、沒有憂鬱傾向的過重或肥胖者，我認為最後發生憂鬱的機會較低。
　　
　　其他可用以解釋的因素，包括不健康的生活型態，如缺乏體能活動或不佳的飲食；使用抗憂鬱藥物，所有這類藥物都會導致體重增加。
　　
　　研究作者們寫道，後續研究應探討憂鬱特徵、藥物使用、體能活力與飲食模式等對於此關聯的可能影響。
　　
　　【最佳範例】
　　美國精神科醫師協會前任理事長、密西根大學精神科、內科與精神科聯合服務副主任Michelle Riba醫師受邀發表評論時表示，此研究是運用統合分析方式對憂鬱和肥胖這兩大公共衛生問題進行研究的最佳範例。
　　
　　Riba醫師向Medscape Psychiatry表示，不過，此次分析有些限制，例如，只有包括成人，我們知道，這些問題有許多在孩童時期就已經發生了。
　　
　　此外，未包括睡眠以及和憂鬱及肥胖有關的睡眠問題等重要因素、糖尿病或心血管疾病患者也未納入。
　　
　　她表示，我們也不知道病患所用的藥物是否會影響心情和肥胖，也未論及躁鬱症、酒精和物質濫用、社會經濟狀態與健康保險等情況。
　　
　　作者們皆宣告沒有相關財務關係。


Bidirectional Link Between Depression and Obesity Confirmed

By Pauline Anderson
Medscape Medical News

March 4, 2010 — Obesity and depression are closely linked in that each raises the risk for the other, a new meta-analysis confirms.

The study found that obese people have a 55% increased risk of developing depression, and those with depression have a 58% increased risk of becoming overweight over time.

These results should spur medical specialties to collaborate in an effort to prevent depression and obesity, each a condition that poses major health problems, said lead author Floriana S. Luppino, MD, Leiden University Medical Center, The Netherlands.

"The first step is to try to do the best we can, based on the facts we know now, and that would be for psychiatrists to monitor their patients’ weight and for internal medicine or general practitioners who see obese or overweight patients to check on their mental state to see if they’re on the way to developing a mood disorder which is mostly treatable."

The study is published in the March issue of Archives of General Psychiatry.

For the analysis, researchers searched the literature for studies published in English up to March 2008. The studies had to have a follow-up period of at least 1 year, express weight as body mass index (BMI), and specify the way depression was assessed. The final analysis included 15 studies.

For the examination of the link between overweight (defined as a BMI between 25 and 29.99) or obesity (defined as a BMI of 30 or more) and depression, the total number of subjects was 55,387. For the inverse relationship, there were 7196 subjects. Some studies provided longitudinal data on both directions.

The pooled odds ratio (OR) was 1.55 (95% confidence interval [CI], 1.22 – 1.98; P < .001) for the 8 studies that examined the association between obesity at baseline and depression at follow-up.

Obesity and Depression Link Stronger in the United States?

The ORs for American studies differed significantly from European ones (P = .05), indicating that the association was stronger among Americans. The reason for this is not clear. However, according to the World Health Organization, the mean adult BMI is higher in the United States than in Europe. "If the mean BMI is higher in the US, and a higher BMI means more depression, that could explain it," said Dr. Luppino.

A significant difference was also seen between ORs for depression outcome as a clinical diagnosis and as depressive symptoms (P = .05), suggesting that the effect of the association is stronger when depression is assessed by a diagnostic clinical interview rather than a self-report symptom list.

As for the inverse relationship — depression causing obesity — the pooled OR of the 9 studies examining the effect of depression on obesity was 1.58 (95% CI, 1.33 – 1.87; P < .001). Subgroup analysis did not show any significant differences.

The pooled OR for depression exposure on overweight was 1.20 (95% CI, 0.87 – 1.66; P = .26). Subgroup analysis found the association stronger with longer follow-up.

The stronger relationship between depression and obesity compared with that between depression and overweight suggests there is a "dose-response" element to the association, said Dr. Luppino.

Psychiatrists Should Monitor Weight

These new data suggest that psychiatrists should regularly monitor the weight of their depressed patients, something that is "easy to do," said Dr. Luppino.

"If you think a patient is borderline overweight or obese, maybe there could be some kind of intervention, for example, sending that patient to a dietitian or someone involved in internal medicine, or to a general practitioner. This may help that patient take control, possibly preventing weight gain with lifestyle changes or dietary changes."

Although previous research suggests that the relationship between depression and excess weight only applies to women, this study confirms it also exists in men.

The relatively long period of follow-up for the studies included in the analysis may be 1 possible explanation.

"In a short period of time, their different hormones could explain why women are more prone to becoming overweight or obese, but in time, other pathways may become involved, and this might explain why, in the end, the risk of obesity or overweight [in depressed patients] exists in both genders,” said Dr. Luppino.

The relationship between depression and obesity is likely multifactorial, involving more than 1 pathway — biological, psychological or both, she said.

Biological pathways could involve inflammation (linked to both depression and obesity), the hypothalamic-pituitary-adrenal axis (also linked to both conditions), and/or insulin resistance (obesity increases risks for diabetes and insulin resistance, which could induce alterations in the brain and increase the risk for depression).

Emphasis on Thinness

One psychological pathway could originate with Western society’s emphasis on thinness, with weight gain contributing to decreased self-esteem, a risk factor for depression, said Dr. Luppino.

The nature of the relationship between obesity and depression may vary from person to person. "For one person, it might be a biological system that’s not working the way it should, but in another person, it could be that self-esteem is low, and if that person is obese, it might be the last push for that person to get depressed."

But perhaps elements of both a biological pathway and a psychological pathway are needed to create the obesity-depression link. "If one gets obese or overweight due to biological factors but self-esteem is great and you don’t have body dissatisfaction, you may not get depressed," said Dr. Luppino.

Genes that increase vulnerability to depression can also play a role, said Dr. Luppino. "For a person with good self-esteem who is overweight or obese but who is not prone to depression, my best guess is that the chances for being depressed at the end are lower."

Other explanatory factors could include unhealthy lifestyles, such as lack of physical activity and poor diet, and the use of antidepressants, all of which can lead to weight gain.

Future research should examine such things as the potential role of depression characteristics, medication use, physical activity, and dietary patterns, the study authors write.

Excellent Example

Reached for a comment, Michelle Riba, MD, associate chair for Integrated Medicine and Psychiatric Services, Department of Psychiatry, University of Michigan, Ann Arbor, and past president, American Psychiatric Association, said the study "is an excellent example of the use of a meta-analytic approach for 2 large public health problems — depression and obesity."

But she did note some limitations of the analysis; for example, it only included adult studies. "We know many of these problems begin much earlier, in childhood, Dr. Riba told Medscape Psychiatry.

As well, important factors, such as sleep and sleep problems related to depression and obesity, and patients with diabetes or cardiovascular diseases were not included.

"We also don’t know about medications that patients might have been on to affect mood and obesity. Bipolar disorder, alcohol and substance abuse, socioeconomic issues, and health insurance are also not addressed," she said.

The authors have disclosed no relevant financial relationships.

Arch Gen Psychiatry. 2010;67:220-229.