童年時的憂鬱會影響灰質發展


  【24drs.com】一篇追蹤孩童達11年的縱向研究結果認為,童年時期的憂鬱與青春期初期的腦部灰質發展減弱有關,減弱程度與憂鬱症狀分數有關。
  
  第一作者、密蘇里州聖路易華盛頓大學醫學院精神科Joan L. Luby醫師表示,研究結果顯示,童年時的憂鬱經驗對於腦部成長發育有實質影響。
  根據這些結果,我們不應再忽視或無法鑑別與治療幼童憂鬱症;這些研究結果線上發表於12月16日的JAMA Psychiatry期刊。
  
  這篇研究包括了聖路易地區的193名3到6歲孩童,蒐集他們在2003年9月至2014年12月間的行為與神經影像資料。
  
  在第一次神經影像掃瞄前與掃描時進行的行為評估指出,90名孩童曾有重度憂鬱異常(major depressive disorder,MDD)之診斷。
  
  以三波方式進行的MRI掃描發現,皮層灰質體積損失和變薄等變化,與第一次影像掃描前發生過MDD顯著相關(體積損失斜率估計:-0.93 cm3;95%信賴區間[CI]為:每掃描波 -1.75 至 -0.10 cm3;變薄斜率估計:-0.0044 mm;95% CI:每掃描波 -0.0077 至 -0.0012 mm )。
  
  作者們解釋,憂鬱症狀分數比平均值多2個標準差的孩童,灰質體積減少程度幾乎是沒有童年期憂鬱症狀者的2倍;同樣地,皮層厚度幾乎是以相同差異快速衰退。
  
  他們指出,重要的是,兩側的皮層灰質厚度減少都與平均憂鬱症狀分數有關,而腦部右半球的體積減少程度更顯著。
  
  作者們寫道,缺乏厚度的單側調查結果、以及腦部左半球的體積略大,這些是值得注意的,因為目前許多探討MDD的文獻注重在腦部右半球。
  
  灰質發展和家族憂鬱病史、創傷性或壓力生活事件等因素之間,並無顯著關聯。
  
  Luby醫師表示,令人驚訝的是,憂鬱症經驗的影響,遠大於已知的因素,如貧窮和母親的支持等。她指出,這是首度有研究探討以三波方式測量灰質厚度變化,所以它真的是一個新領域,其他研究僅探討單一結果影像波。
  
  研究結果與憂鬱成人的灰質體積模式一致,Luby醫師指出,他們提出可塑性的議題,對於治療兒童和成人之潛在影響。她表示,有證據顯示灰質的可塑性,即使是成年人,有著多種實務作法。
  
  所以,[可塑性]顯然可能是基於我們所知,腦部可能隨著經驗和「練習」而有能力改變。還不知道治療是否會影響這個效果,但是,這是一個成熟的、新的調查領域。
  
  在這篇研究的編輯評論中,Ian H. Gotlib博士等人同意,需要更多研究以確認治療憂鬱對於青少年腦部發展的影響。
  
  Gotlib博士表示,這項研究可能闡明,憂鬱對突觸修剪等議題的影響。
  
  加州史丹佛大學心理學系主任、David Starr Jordan名譽教授Gotlib博士表示,作者們發現,憂鬱程度嚴重的青少年,灰質總體積更急遽減少,這表示,對於曾發生憂鬱症狀者,突觸修剪特別激烈。
  
  在未來,這相當有助於檢視這些皮層變化和特定憂鬱症狀變化的關聯,以評估憂鬱兒童和青少年的神經基礎是否有特異性。
  
  資料來源:http://www.24drs.com/
  
  Native link:Early Depression May Affect Gray Matter Development

Early Depression May Affect Gray Matter Development

By Nancy A. Melville
Medscape Medical News

Depression in early childhood is associated with reductions in gray matter development in the brain during early adolescence, with the reductions linked to the number of depressive symptoms, suggest results of a longitudinal study tracking children for up to 11 years.

"The [findings show] that the experience of early childhood depression has a material impact on the way the brain grows and develops," lead author Joan L. Luby, MD, Department of Psychiatry, the Washington University School of Medicine, St. Louis, Missouri, told Medscape Medical News.

"Based on [these findings], we should no longer ignore or fail to identify and attempt to treat early childhood depression."

Their results were published online December 16 in JAMA Psychiatry.

The study involved 193 children aged 3 to 6 years in the St. Louis area for whom behavioral and neuroimaging data were collected between September 2003 and December 2014.

Behavioral assessments taken before and at the time of the first neuroimaging scan indicated that 90 children had prevoiusly received a diagnosis of major depressive disorder (MDD).

MRI scans taken in three waves showed alterations in cortical gray matter volume loss and thinning that were significantly associated with having had an episode of MDD prior to the first imaging scan (volume loss slope estimate, -0.93 cm3; 95% confidence interval [CI], -1.75 to -0.10 cm3 per scan wave; thinning slope estimate, -0.0044 mm; 95% CI, -0.0077 to -0.0012 mm per scan wave).

"Children with depression symptom scores [that were] 2 SDs [standard deviations] above the mean had reduction in volumes of gray matter at almost twice the rate of those with no childhood depression symptoms," the authors explain. "Similarly, cortical thickness also decreased more rapidly at almost the same rate."

Importantly, the decreases in cortical gray matter thickness that were associated with mean depression symptom scores were bilateral, whereas volume decreases were more significant in the right hemisphere, they note.

"The absence of lateralized findings for thickness and the marginally significant finding on the left hemisphere for volume is notable given that much of the extant literature on MDD has discussed the right hemisphere," the authors write.

No significant associations were seen between gray matter development and factors that included a family history of depression or experiences of traumatic or stressful life events.

"It was surprising that the experience of depression was so powerfully predictive above other known established effects, such as poverty and maternal support, etc," Dr Luby said.

"This was the first study to report on change in gray matter across development measured at three waves, so it really is new territory," she added. "Other studies have only looked at one outcome imaging wave."

The findings are consistent with volumetric gray matter patterns in depressed adults, and Dr Luby noted that they raise the issue of plasticity and the potential effect of treatment in children and adults alike.

"There is evidence for plasticity of gray matter with intense practice of various kinds of tasks even in adults," she said.

"So [plasticity] certainly is possible based on what we know about the brain's ability to change with experience and 'exercise.' It is unknown whether treatment will impact this effect, but this is a ripe area for new investigation."

Synaptic Pruning

In an editorial that accompanied the study, Ian H. Gotlib, PhD, and colleagues agree that more research is needed to determine the role of treatment of depression in brain development during adolescence.

The study may shed light on the role of depression on issues such as synaptic pruning, Dr Gotlib told Medscape Medical News.

"The authors' finding that global volume of gray matter declines more steeply in adolescents with more severe depression suggests that synaptic pruning is particularly aggressive in individuals who have experienced symptoms of depression," said Dr Gotlib, who is the David Starr Jordan Professor and chair of the Department of Psychology at Stanford University, in California.

"It will be useful in future work to examine the relations of these cortical changes with changes in specific symptoms of depression to assess whether there is specificity in the neural underpinnings of depression in children and adolescents," he added.

This study was supported by grants from the National Institute of Mental Health, the National Institutes of Health Blueprint, and the National Institutes of Health. Dr Luby has received royalties from Guilford Press. Coauthors of the article have served in consulting relationships with Pfizer, Amgen, and Roche. Dr Gotlib has disclosed no relevant financial relationships.

JAMA Psychiatry. Published online December 16, 2015.

    
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