Wikipedia:Reference desk/Archives/Science/2015 June 13

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June 13

Why do some people die of cigarette smoking but others live to long ages?

Assuming they smoke at the same rate. Why? 69.121.131.137 (talk) 14:39, 13 June 2015 (UTC)

Why do some people who go for a walk in the savannah get eaten by lions while others survive untouched? Smoking increases your probability of developing certain medical conditions. See risk factor. – iridescent 15:07, 13 June 2015 (UTC)

A more interesting question might be why chain smokers can die from such a variety of ailments: cancer, emphysema, COPD, stroke, heart attack, etc. The bad stuff in the smoke affects different people different ways. ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:16, 13 June 2015 (UTC)

That probably relates to the large number of toxic substances in cigarette smoke. Carcinogens, mutagens, and chemical irritants. StuRat (talk) 10:43, 14 June 2015 (UTC)

That suggests genetic predisposition to one or more of those things. You can get any of those things without having been a smoker. Maybe smoking just ratchets up the probability exponentially. ←Baseball Bugs ^{What's up, Doc?} carrots→ 11:31, 14 June 2015 (UTC)

Genetics may play a factor, but it's not the only reason people are affected differently any more than someone being killed by a lion or hippo is just because of genetics. As for your last point, isn't that what Iridescent's reply said? (Well not necessarily exponentially.) Nil Einne (talk) 11:37, 14 June 2015 (UTC)

People get eaten by lions because of dumb luck. People die of smoking while others live to extremely old ages because of a physical reason, not dumb luck. 69.121.131.137 (talk) 11:38, 14 June 2015 (UTC)

Carcinogenesis does involve some relatively predictable epigenetic processes, but tumor initiation in particular tends to involve some mutation events, i.e. dumb luck. Wnt (talk) 12:43, 14 June 2015 (UTC)

And getting killed by a lion can be affected by genetics, too. That American woman who just got mauled to death in an African lion preserve had her car window down, contrary to the posted warnings. I would never have put my window down, and my genetics are responsible, at least in part, for making me more risk averse than her. StuRat (talk) 15:11, 14 June 2015 (UTC)

Recent studies have shown that there is a strong genetic component in longevity. People belonging to families that have a larger number of centenarians than average do not typically live according to healthier lifestyles than the general population. So, it's down to the body repairing itself better than average which also means that if you are predisposed to live a lot longer than average, your body will likely clean up the mess caused by smoking more efficiently compared to people who are not genetically destined to live as long. Count Iblis (talk) 14:01, 14 June 2015 (UTC)

Is PTSD considered a learning disability?

Just wondering. — Preceding unsigned comment added by 24.20.204.170 (talk) 19:32, 13 June 2015 (UTC)

Considered by whom? Probably the most authoritative reference material for such questions is the DSM V, published on behalf of the American Psychiatric Association. The PTSD Fact Sheet expressly states that post-traumatic stress disorder now deserves its own chapter, because it is no longer classed as an anxiety disorder (as it was in the previous edition, DSM IV). Neither the former nor the current classification of PTSD places it alongside "learning disorders," which are typically classed as either an intellectual disability or other Specific Learning Disorders.

Here is another ser of worthwhile reading: Psychiatric comorbidity: is more less? (2004) and Comorbidity in psychiatry: Way forward or a conundrum? (2006) "The traditional practice of understanding and explaining all the symptoms and signs of a person presenting to mental health facilities was synchronous with the hierarchical system of classification. The clinical dictum of ‘one person one diagnosis’ was in keeping with the early classification systems wherein the diagnostic groups were arranged in hierarchy..." ..."The current systems of DSM-IV and ICD-10 actively encourage multiple diagnoses in the same person, regardless of the possible contribution to aetiology, allowing the maximum amount of diagnostic information." In other words, the present norm in clinical psychiatry is to diagnose PTSD and other syndromes or diseases if symptoms are present that pertain to multiple diagnoses, irrespective of whether the cause of the symptoms is related. Not every clinical psychatrist favors this norm.

Nimur (talk) 19:42, 13 June 2015 (UTC)

See Posttraumatic stress disorder and Learning disability. Our articles, which refer to and reflect DSM IV, DSM V, and the ICD (which is considered the authoritative source in Europe), do not say anything about PTSD being a learning diability. The symptoms and effects of PTSD have a scope that goes beyond learning, and a diagnosis of a learning disability would be incorrect if the learning disability is part of the pattern of PTSD. Robert McClenon (talk) 19:51, 13 June 2015 (UTC)

If someone breaks both arms and is unable to write, they'll be unable to take notes in class - and will presumably find it harder to learn. Do we consider a broken arm to be a "learning disorder"? No, we don't. Does having both arms broken make it harder to learn? Yes, it does. Heck, having a common cold makes it harder to learn. So it's perfectly possible (indeed HIGHLY likely) that someone with the more profound symptoms of PTSD will find it harder to learn - but that doesn't make PTSD a "learning disorder" per se. SteveBaker (talk) 01:54, 14 June 2015 (UTC)