抽菸與憂鬱風險增加有關
作者：Deborah Brauser
出處：WebMD醫學新聞
June 9, 2010 (June 11, 2010更新 ) — 根據紐西蘭研究者發表的大型縱向研究結果，抽菸者發生憂鬱症的風險增加。
該研究也發現，相較於沒有尼古丁依賴的人，有尼古丁依賴者發生憂鬱症狀的風險超過兩倍。
第一作者、紐西蘭Dunedin Otago大學「Christchurch Health and Development Study」研究負責人David M. Fergusson博士在聲明稿中表示，有關抽菸和憂鬱之關聯的原因還不清楚。
Fergusson博士表示，不過，可能是尼古丁引起腦中神經傳導物質活性改變，導致憂鬱風險增加。
他向Medscape Psychiatry表示，該篇報告的主要訊息是，抽菸除了造成生理傷害，尼古丁依賴也會增加心智健康問題的風險，顯然的，給醫師們的訊息是，鼓勵那些復發憂鬱者戒菸。
該研究發表於6月1日的英國精神病學期刊(British Journal of Psychiatry)。
【路徑還不清楚】
作者們寫道，雖然最近有許多研究聚焦在物質濫用和心智異常之間的關聯，但是過去的研究並未闡明抽菸和憂鬱之關聯的路徑。
Fergusson博士表示，這個關聯反映出抽菸和憂鬱的共通因素嗎？或者是憂鬱增加了抽菸比率？或者是抽菸導致憂鬱？本研究的目標是，更清楚探討這個爭議多年的議題。
研究者檢視了出生於1977年中期1,265位(635名男性以及630名女性)的資料，這些對象來自「Christchurch Health and Development Study」研究。
在該世代18、21和25歲時，使用組合型國際診斷性會談(Composite International Diagnostic Interview)詢問他們在過去12個月間是否有任何憂鬱症狀，以及使用精神疾病診斷與統計手冊第四版(Diagnostic and Statistical Manual of Mental Disorders, 4th Edition)、症狀準則，探討他們在過去一個月時的抽菸習慣。
研究者接著使用固定效應回歸模式校正研究第一階段時的干擾因素，使用結構式方程式模式方法(methods of structural equation modeling)校正第二階段，用來探討因果關係。
【顯著關聯】
研究結束時，研究者發現，在每個年紀，尼古丁依賴症狀增加程度和憂鬱症狀增加比率有顯著關聯(P < 0.0001)。
此外，相較於沒有尼古丁依賴症狀者，有至少5個尼古丁依賴症狀者，有憂鬱症狀的比率是2.13倍(95%信心區間，1.98-2.31)。
校正干擾因素之後，尼古丁依賴和憂鬱症狀之間依舊有顯著關聯(P < .05)。
研究者也發現，雖然尼古丁依賴症狀和憂鬱症狀有顯著關聯，憂鬱症狀並未和尼古丁依賴症狀有顯著關聯(P = 0.21)。
研究作者們解釋，這意味著，抽菸增加了發生憂鬱症狀的風險，而不是憂鬱者的抽菸比率會增加。
不過，他們警告表示，他們的研究並未證明抽菸引起憂鬱，應被視為有可能而不是已經確定。
Fergusson博士報告指出，下一個階段是，進行後續的腦部研究，以檢視與尼古丁依賴及心情狀態有關的可能路徑。
他指出，對憂鬱病患進行戒菸的隨機試驗也是有趣的，以確認它是否可以進一步減少後續憂鬱發作的風險。
【該領域的重要貢獻】
UMAss紀念健康照護體系、麻塞諸塞大學醫學院精神科主任、教授Douglas Ziedonis博士向Medscape Psychiatry表示，我喜歡這個研究，我認為它對該領域有重要貢獻，也提出此領域需要後續研究的實際方向。
未參與該試驗的Ziedonis博士表示，許多研究著眼於憂鬱和抽菸之間的關聯，本研究的新重要貢獻是，實際提供某些資料支持原本視為可能之關聯的因果關係。
他指出，他希望可以看到更年輕之研究對象的資料，特別是12-16歲者。我不知道在紐西蘭的情況是怎樣，但是在美國，菸癮已經是一種青少年疾病，前述的這段年紀是多數孩子們開始抽菸並上癮的年紀。
我認為這類研究證實了[國家精神衛生研究院(NIMH)]和[國家藥物濫用研究所(NIDA)]，支持我們使用前瞻方式、採取流行病學和統計方式探討此關聯，另外也可使用腦部影像、遺傳學和其他方式來探討因果關係。
Ziedonis博士結論表示，這是一個重要的公共衛生議題，我認為，它對精神科醫師而言特別有意義。
紐西蘭健康研究委員會、國家兒童健康研究基金會、Canterbury醫學研究基金會以及紐西蘭樂透資金委員會等支持該研究。Fergusson博士和Ziedonis博士皆宣告沒有相關財務關係。
Smoking Linked to Increased Depression Risk
By Deborah Brauser
Medscape Medical News
June 9, 2010 — Individuals who smoke cigarettes may increase their risk of developing depression, according to results from a large longitudinal study from New Zealand researchers.
The study also found that those who were dependent on nicotine were more than twice as likely to have depressive symptoms as those who were not dependent.
Lead researcher David M. Fergusson, PhD, professor and director of the Christchurch Health and Development Study at the University of Otago, Dunedin, New Zealand, said in a statement that the reason for the relationship between smoking and depression is unclear.
"However, it's possible that nicotine causes changes to neurotransmitter activity in the brain, leading to an increased risk of depression," said Dr. Fergusson.
"The main message of the paper is that in addition to the harm that smoking does to physical health, nicotine dependence may also increase risks of mental health problems," he told Medscape Psychiatry. "The message for clinicians, clearly, is to encourage smoking cessation amongst patients subject to recurrent depressive episodes."
The study was published June 1 in the British Journal of Psychiatry.
Pathways Unclear
Although there have been a number of recent studies that focused on the association between substance use and mental disorders, past research "has not elucidated the pathways by which smoking is associated with depression," write the study authors.
"Does [this association] reflect common factors [from] both smoking and depression? Or does depression increase rates of smoking? Or does smoking lead to depression? The aim of this study was to cast further light on an issue that had been debated for some years," said Dr. Fergusson.
The investigators examined data on 1265 people (635 men, 630 women), born in mid-1977, from the Christchurch Health and Development Study. The cohort participants were asked at the ages of 18, 21, and 25 years whether they had any symptoms of depression during the last 12 months, using the Composite International Diagnostic Interview, and about their smoking habits during the past month, using Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, symptom criteria.
The researchers then used fixed-effects regression modeling to adjust for confounding during the first stage of the study and methods of structural equation modeling for the second stage, which explored the direction of causality.
Significant Association
At the end of the study, the investigators found that "at each age, increasing levels of nicotine-dependence symptoms were significantly associated with increasing rates of depressive symptoms (P < 0.0001)."
In addition, "those reporting at least 5 symptoms of nicotine dependence had rates of depressive symptoms that were 2.13 times (95% confidence interval, 1.98-2.31) those of individuals who reported no symptoms of nicotine dependence."
After adjusting for confounding factors, significant associations were still found between nicotine dependence and symptoms of depression (P < .05).
The researchers also found that although the "nicotine-dependence symptoms were significantly related to depressive symptoms, depressive symptoms were not significantly related to nicotine-dependence symptoms (P = 0.21)."
This means that smoking increased the risk of developing depressive symptoms, not that smoking was increased as a result of the participants being depressed, explain the study authors.
They caution, however, that their study does not prove that smoking causes depression and that it "should be viewed as suggestive rather than definitive."
Dr. Fergusson reported that the next step "is clearly further brain research examining the possible pathways that may link nicotine dependence and mood states."
"It will also be of interest to conduct randomized trials of smoking cessation in depressed patients to determine the extent to which [it] may reduce risks of further depressive episodes," he added.
This study was supported by grants from the Health Research Council of New Zealand, the National Child Health Research Foundation, the Canterbury Medical Research Foundation, and the New Zealand Lottery Grants Board. Dr. Fergusson has disclosed no relevant financial relationships.
Br J Psych. 2010;196:440-446.
