26 year study suggests smoking causes depression

FreedomNicotine
FreedomNicotine

1:37 PM - Jul 28, 2010 #1

Tobacco smoking as a risk factor for depression.
A 26-year population-based follow-up study
 
Journal of Psychiatric Research
Article in Press, Corrected Proof
Available online 13 July 2010.
 
Trine Flensborg-Madsen, Mikael Bay von Scholten, Esben Meulengracht Flachs, Erik Lykke Mortensen, Eva Prescott and Janne Schurmann Tolstrup
Abstract Background A key question regarding the documented association between smoking and depression is whether it reflects a causal influence of smoking on depression; however, only a limited number of longitudinal studies exist in the literature, all of which have relatively short time frames. The purpose was to prospectively assess the risk of depression according to daily tobacco consumption in a Danish longitudinal study.

Methods A prospective cohort study, the Copenhagen City Heart Study (n = 18,146), was analyzed with up to 26 years of follow-up. It contains three updated data sets on tobacco consumption and potential confounding factors. The study population was linked to Danish hospital registers to detect registrations with depression. Individuals with depression before baseline were excluded.

Results Women smoking more than 10 g of tobacco per day were at significantly increased risk of depression compared to women who did not smoke. The adjusted risk of depression among women smoking 11–20 g per day was 1.74 (CI:1.33–2.27) and 2.17 (CI:1.45–3.26) among women smoking more than 20 g per day. For men, there was an increased risk of depression for those smoking more than 20 g per day (HR = 1.90; CI:1.05–3.44). All tests for linear trend were significant (all p < 0.01). The estimates remained significant in sensitivity analyses aiming to eliminate reverse causation, and in analyses based on a reduced sample without individuals with chronic diseases or psychiatric disorders other than depression.

Conclusion The study suggests that smoking is associated with increased risk of developing depression. This underlines the potentially harmful consequences of smoking for mental health and supports efforts to prevent and stop smoking.

PubMed Link:  http://www.ncbi.nlm.nih.gov/pubmed/20630542

http://www.sciencedirect.com/science/journal/00223956
Last edited by FreedomNicotine on 1:46 PM - Jul 28, 2010, edited 2 times in total.
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Joined: 7:22 PM - Nov 11, 2008

12:54 AM - Oct 19, 2010 #2

Cigarette smoking and depression:
tests of causal linkages using
a longitudinal birth cohort

 
The British Journal of Psychiatry (2010) 196: 440-446.

 
Joseph M. Boden, PhD, David M. Fergusson, PhD and L. John Horwood, MSc 
Abstract

Background

Research on the comorbidity between cigarette smoking and major depression has not elucidated the pathways by which smoking is associated with depression.

Aims

To examine the causal relationships between smoking and depression via fixed-effects regression and structural equation modelling.

Method

Data were gathered on nicotine-dependence symptoms and depressive symptoms in early adulthood using a birth cohort of over 1000 individuals.

Results

Adjustment for confounding factors revealed persistent significant associations between nicotine-dependence symptoms and depressive symptoms. Structural equation modelling suggested that the best-fitting causal model was one in which nicotine dependence led to increased risk of depression. The findings suggest that the comorbidity between smoking and depression arises from two routes; the first involving common or correlated risk factors and the second a direct path in which smoking increases the risk of depression.

Conclusions

This evidence is consistent with the conclusion that there is a cause and effect relationship between smoking and depression in which cigarette smoking increases the risk of symptoms of depression.
 
http://bjp.rcpsych.org/cg...ntent/abstract/196/6/440






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Smoking link to depression By Martin Johnston
4:00 AM Wednesday Jun 2, 2010

Smoking may cause an increased risk of depression, according to a New Zealand study which has followed 1200 people since they were born in 1977.

Smoking and major depression have long been known to be linked.

But which is the primary cause has been unclear, and it is possible that they reinforce each other.

Studies have suggested that some people who have depression smoke as a form of self-medication.

Researchers from Otago University at Christchurch, led by Professor David Ferguson, analysed data collected when participants in their study were in the late teens to mid-20s.

They concluded it is probably smoking that increases the risk of suffering symptoms of major depression, rather than the reverse.

They found that at the age of:

* 18 years - 14 per cent of the study participants were addicted to nicotine and 18 per cent had serious depression.

* 21 years - 25 per cent were addicted and 18 per cent had depression.

* 25 years - 23 per cent were addicted and 14 per cent had depression.

"Overall, those reporting at least five symptoms of nicotine dependence had rates of depressive symptoms that were 2.13 times those of individuals who reported no symptoms of nicotine dependence," says the researchers' paper.

The findings were published yesterday in the British Journal of Psychiatry.

The paper says statistical calculations suggested the cause-and-effect link was one-way, from nicotine addiction to depression.

They found no evidence of a link in the reverse direction, from depression to smoking.

"The reasons for this relationship are not clear," said Professor Ferguson. "However, it's possible that nicotine causes changes to neurotransmitter activity in the brain, leading to an increased risk of depression."

SMOKING RISKS

Smoking is linked to an increased risk of: * Cancer * Heart disease * Stroke * Impotence * Probably severe depression
Story Source Link 

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