Monday, September 16, 2013

Booze doesn't cause depression

This is based on generalizations from a known atypical group so is interesting but not conclusive

There is no truth to the long-held belief that alcohol causes depression, clinical neuroscientists from The University of Western Australia have concluded.

Professor Osvaldo Almeida, of UWA's School of Psychiatry and Clinical Neurosciences, said that until now everyone had assumed that alcohol caused people to become depressed, particularly if consumed at excessive levels.

"Even one of the diagnoses we have for depressive disorders - Substance Induced Mood Disorder - is a diagnosis where alcohol plays a role," Professor Almeida said.  "However, because of the observational nature of the association between alcohol and depression, and the risk of confounding and bias that comes with observational studies, it is difficult to be entirely certain that the relationship is causal.

"For example, people who drink too much may also smoke, have poor diets and other diseases that could explain the excess number of people with depression among heavy drinkers."

Professor Almeida and fellow researchers with the long-running Health in Men Study (HIMS) decided to search for a causal link via physiological pathways instead: specifically the genetic polymorphism, or mutation, most closely associated with alcohol metabolism.

"We now know that certain genetic variations affect the amount of alcohol people consume," Professor Almeida said. "There is one particular genetic variation that affects the enzyme responsible for the metabolism of alcohol.  This variation produces an enzyme that is up to 80 times less competent at breaking down alcohol.  Consequently, people who carry this variation are much less tolerant to alcohol.  In fact, there is now evidence that alcohol-related disorders are very uncommon in this group.

"Now, if alcohol causes depression, then a genetic variation that reduces alcohol use and alcohol-related disorders, should reduce the risk of depression.  The great advantage of looking at the gene is that this association is not confounded by any other factors - people are born like that."

The researchers analysed the triangular association between the genetic mutation, alcohol and depression in 3873 elderly male participants of the HIMS study, using data collected over three to eight years.

"We found (as expected) that this particular genetic variant was associated with reduced alcohol use, but it had no association with depression whatsoever," Professor Almeida said.

"The conclusion is that alcohol use neither causes nor prevents depression in older men.  Our results also debunk the view that mild to moderate alcohol consumption may reduce the risk of depression."

He said the association observed between alcohol and depression was likely explained by other factors, but not by alcohol itself.

"It doesn't mean alcohol is entirely safe and people can consume it in whatever way they like.  We know that alcohol when consumed in excess does create a lot of health problems - but what we now know is that one of those problems is not depression."

HIMS is a longitudinal study of 12,201 men aged 65-83 when recruited in 1996.  The HIMS research team, largely made up of UWA researchers, has so far published more than 100 papers on a wide range of men's health and ageing issues.

A paper on the study  "The triangular association of ADH1B genetic polymorphism, alcohol consumption and the risk of depression in older men" as published in the journal Molecular Psychiatry


Does anorexia have a genetic link? New theory suggests the disorder may not be purely down to social pressures

Anorexia is clearly an obsessive-compulsive disorder so is highly likely to be strongly genetic.  Pretty heavy speculation below

Anorexia could be caused by a genetic mutation, according to new research.  A study of the DNA of more than 3,000 people found the eating disorder may be caused by mutations that interfere with the processing of cholesterol, disrupting mood and diet.

The findings, published in the journal Molecular Psychiatry, may lead to the development of drugs to treat the condition.

Sufferers starve themselves because they believe they are fat, and more than one in ten cases are fatal making it the deadliest of psychiatric illnesses. Just 30 per cent of patients make a full recovery.

Although many experts believe the condition is caused by social pressure, there is growing evidence there may also be a genetic link.

Researchers analysed genetic information from more than 1,200 anorexia patients and almost 2,000 healthy controls.

They looked for variants of genes that had already been linked to feeding behaviour or been flagged up in previous studies.

Just a handful of more than 150 genes studied showed signs of a link, but one stand out was the gene EPHX2, which controls an enzyme that regulates the burning of cholesterol.

Professor Nicholas Schork, of The Scripps Research Institute, La Jolla, California, said: ‘When we saw that, we thought we might be onto something, because nobody else had reported this gene as having a pronounced role in anorexia.’

Anorexia affects up to one in a hundred women but how it develops is still not fully understood.

Professor Schork added: ‘These findings point in a direction probably no one would have considered taking before.’

His researchers followed up with several replication studies, each using a different cohort of anorexia patients and controls, as well as different genetic analysis methods.

The scientists continued to find evidence that certain variants of EPHX2 occur more frequently in people with anorexia.

To help make sense of these findings, they looked at existing data from a large-scale, long-term heart disease study and determined that a subset of the implicated EPHX2 variants have the effect of altering the normal relationship between weight gain and cholesterol levels.

Professor Schork said: ‘We thought with further studies this EPHX2 finding might go away, or appear less compelling, but we just kept finding evidence to suggest it plays a role in anorexia.’

It is not yet clear how EPHX2 variants that cause an abnormal metabolism of cholesterol would help trigger or maintain anorexia.

But Professor Schork noted people with anorexia often have remarkably high cholesterol levels in their blood, despite being severely malnourished.

Moreover, there have been suggestions from other studies weight loss, for example in people with depression, can lead to increases in cholesterol levels.

At the same time, there is evidence cholesterol, a basic building block of cells, particularly in the brain, has a positive association with mood.

It is possible some anorexics for genetic reasons may feel an improved mood, from having higher cholesterol, by not eating.

Professor Schork explained: ‘The hypothesis would be in some anorexics the normal metabolism of cholesterol is disrupted, which could influence their mood as well as their ability to survive despite severe caloric restriction.’

Around 60,000 Britons have anorexia. Nine out of ten sufferers are women, the majority aged 15 to 25.


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