It is known that depression is associated with cigarette smoking, but the nature of this association is discussed under various hypotheses. First, according to the so called self-medication hypothesis, those who suffer from depressive symptoms smoke cigarettes in order to alleviate their symptoms. According to the second assumption, chronic persistent smoking may have a role in the etiology of depression. The third hypothesis suggests that there is a reciprocal mechanism between smoking and depression. The fourth hypothesis says that there are shared underlying genetic factors explaining this co-morbidity.
This study conducted in the Department of Public Health at the University of Helsinki explored, which of those assumptions would be supported by the data, when smoking behavior and changes in it is considered as a predictor of depressive symptoms. The researchers had access to the data collected within the Finnish Adult Twin Cohort Project. There were about four thousand male and five thousand female twins, whose health and health behavior were followed-up through 15 years.
Data on smoking behavior and changes in it between 1975 and 1981 were analyzed as a predictor of depressive symptoms measured in 1990. The analyses were adjusted for other factors known to predict depression. Because the data consisted of twins it was possible to test the causality between smoking and depression by using twin pairs discordant for depression, where the twin without depression served as a matched control for his/her co-twin with depression. Additionally, it was possible to explore potential shared genetic influences underlying the association.
The results suggest that first, persistent chronic cigarette smoking predicts depressive symptoms. However, when adjusted for other factors associated with depression, the elevated risk of persistent smoking remained significant among men only. ”The result that chronic smoking may actually have a role in the etiology of depression, may be surprising, as nicotine as such – in short term – is assumed to have some positive effects on mood”, says Dr. Tellervo Korhonen from the Department of Public Health at the University of Helsinki, and continues: ”We should look for explanation to our result from long term effects of cigarette smoking, from addiction mechanisms and from other substances than nicotine within tobacco smoke.”
Secondly, there was evidence suggesting that those smokers who had quit had elevated depression risk in relatively short term. The association of quitting smoking and depressive symptoms gives us indirect evidence on the self-medication hypothesis. Dr. Korhonen emphasizes, however, the further evidence within the same study showing that those smokers who had quit successfully and remained abstinent through the follow-up did not have elevated depression risk compared to the never smokers. This may reflect a relatively long recovery process from the adverse effects of cigaret1te smoking.
”The mechanisms underlying the association between smoking and depression are very complicated. Although nicotine as such may have short term positive effects on concentration and possibly on mood, long term exposure to tobacco smoke may be one risk factor in development of depression. However, this mechanism is still relatively unknown. Thus, there is need for further research and evidence in order to make an unambiguous statement that ‘smoking cigarettes cause depression’. Examination of potential shared genetic vulnerability for both tobacco dependence and depression is among the further challenges”, Dr. Korhonen is discussing the evidence so far. According to Korhonen, one can already say that – as in prevention of many other diseases – also in prevention of depression smoke-free life and successful smoking cessation seem to have a positive impact.
This report is based on a research article published in the Psychological Medicine –scientific journal. The authors include researchers from the University of Helsinki, the National Public Health Institute, the Finnish Institute of Occupational Health and the Harvard University, Boston, USA.
Paivi Lehtinen | alfa
New study from the University of Halle: How climate change alters plant growth
12.01.2018 | Martin-Luther-Universität Halle-Wittenberg
Disarray in the brain
18.12.2017 | Universität zu Lübeck
On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.
We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...
What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.
Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...
08.01.2018 | Event News
11.12.2017 | Event News
08.12.2017 | Event News
19.01.2018 | Materials Sciences
19.01.2018 | Health and Medicine
19.01.2018 | Physics and Astronomy