Genetic link to suicide risk

Researchers from Johns Hopkins University in Baltimore have identified a gene that could be linked to an increased risk of attempting suicide. The researchers studied 2,698 people with bipolar disorder, 1,201 of whom had a history of suicide attempts. Those with one copy of a genetic variation on chromosome 2 were 1.4x as likely to have attempted suicide while those with two variations were almost three times as likely. The gene involved - ACP1 - leads to increased levels of a protein called ACP1 in the brains of people who had committed suicide. The protein is thought to influence the same biological pathway - albeit in a different direction - as lithium, a drug known to reduce the rate of suicidal behaviour.

Cocaine, genes and shrinking brains

People who are addicted to cocaine have less grey matter in the frontal parts of their brain and in their hippocampi. The frontal parts of the brain are important for paying attention and organising one's behaviour while the hippocampus is important in learning and memory. A team of researchers led by Nelly Alia-Klein at the U.S. Department of Energy's Brookhaven National Laboratory have found that people with a certain genetic make up may be more vulnerable to the adverse effects of cocaine use than other people. The researchers studied 82 people. 40 of them were addicted to cocaine and 42 were healthy controls. The researchers took DNA samples and scanned the subjects' brains. The cocaine addicts with a low MAOA (monoamine oxidase A) genotype had lower grey-matter density in the frontal parts of the brain than the other cocaine addicts. The genes are responsible for levels of MAOA, an enzyme which regulates neurotransmitters such as serotonin and dopamine that regulate mood.

Genes, brainpower and scary areas

Most researchers now think that our genes, our environment, our experiences and our behaviour work together to increase, or decrease, our risk of disease. One gene which is linked to an increased risk of developing Alzheimer's disease is APOE4 and researchers from Drexel University School of Public Health in Philadelphia have been researching how this gene is affected by living in a 'psychosocially hazardous' - i.e. scary - neighbourhood. They studied 1,124 people aged between 50 and 70, testing them for the gene and giving them a series of cognitive tests. The people with the risky variation of the gene who lived in the scariest neighbourhoods performed worst in the tests. However, those without the gene who lived in the scary areas and those with the gene who lived in less-frightening parts of town were at no greater risk of worse performance.

Another gene linked to increased risk of mental illness

A team of researchers from Shanghai Jiao Tong University have been looking into the links between genetics and schizophrenia. They studied 12,229 people in Shanghai: 5,772 had no mental-health problems, 4,187 had schizophrenia, 1,135 had bipolar disorder and 1,135 had depression. The study found that variations in the BCL9 gene led to a greater risk of schizophrenia and were also associated with bipolar disorder and depression.

Li, Junyan ... [et al] - Common variants in the BCL9 gene conferring risk of schizophrenia Archives of General Psychiatry 2011; 68(3): 232-241

Sex differences, genes and autism

Men are more likely to suffer from autism than women and men with autism have more testosterone than men without the condition. Researchers at Washington State University have been looking into the influence of male and female sex hormones on a gene called RORA. The gene affects the development of the cerebellum and many other processes that are important in autism and also regulates the production of a protein called aromatase - levels of which are reduced in the brains of people with autism. The researchers found that a decrease in aromatase leads to a build up in testosterone which in turn decreases the levels of RORA and further reduces aromatase. Female sex hormones were found to increase the levels of RORA in brain cells which in turn increases levels of aromatase. The researchers think that the effects of these hormones on the RORA gene could be responsible for some of the differences between the sexes in the prevalence of autism.

Gene linked to drunken impulsiveness

Some people who are relatively mild-mannered most of the time can become violent after a few drinks. Researchers from the National Institute on Alcohol Abuse and Alcoholism in Maryland compared the genes of people who had acted impulsively under the influence with those whose behaviour remained more or less the same. They found that those people who had a DNA variation which blocked the action of a gene known as HTR2B were more likely to behave impulsively after they had been drinking.

Genes and anorexia

A team of researchers from the Center for Applied Genomics at The Children's Hospital of Philadelphia has been looking into the genetics of anorexia nervosa. They studied 4,736 people, 1,003 of whom had anorexia and compared their genes. The study found that variations in two genes - OPRD1 and HTR1D - increased the risk of developing the condition. However, most scientists think that although genes might increase the risk of developing mental-health problems the true causes of these conditions lie in a combination of genetics and people's upbringing and experiences.

Genes, autism and neural connections

Scientists at the Scripps Translational Science Institute in San Diego have been using cutting-edge neuroscience to look into the links between genetics and autism. They used MRI (magnetic resonance imaging) brain scans to study 32 children who had a variation in a gene called CNTNAP2 which is associated with an increased risk of autism, attention deficit hyperactivity disorder (ADHD), Tourette's syndrome and schizophrenia. Half of the children had been diagnosed with autism while half were unaffected. The researchers used the MRI scans to see what was going on in the children's brains while they carried out a language-learning task. Compared to children without the variation in the gene the children with it had a superfluity of connections in their prefrontal cortices and a lack of connections between the prefrontal cortex and the left side of the brain, which is connected with language.

The science of sleep and genes

Some people seem to manage quite happily on four hours of sleep a night while others turn into zombies. A new study by researchers at the University of Pennsylvania School of Medicine suggests that this may, in part at least, be down to our genes. They studied 129 healthy adults, 37 of whom, although unaffected, carried a gene called DQB1*0602 which is associatd with narcolepsy. The participants' sleep was restricted to four hours a night and they were given various tests of memory and attention. The people with the narcolepsy gene were sleepier and more fatigued while both fully rested and sleep deprived and they woke up more during the night; they also spent less time in deep sleep. However, there was no difference in their performance on the memory and attention tasks and in their ability to resist sleep during the daytime.

Deleted genes and schizophrenia

Researchers from Emory University in Atlanta have been looking into the links between genetics and schizophrenia among Ashkenazi (from Germany and Europe) Jews. They compared people with and without schizophrenia and analyzed their genetic makeup. A deleted gene on the 3rd chromosome was linked to a seventeen-fold increase in the risk of schizophrenia.

You can find out more about this research by clicking on the title of this post.

Suicide and genetics

Nearly a million people killed themselves in 2000 and scientists estimate that 1.5 million will in 2020. It is thought that about 40% of the variation in people's suicidal behaviour could have a genetic basis and a team of Spanish researchers based at Mount Sinai Hospital and Columbia University in New York analysed 840 different variations found in 312 genes which affect the brain. They found that three variations in three different genes allowed them to correctly classify 69% of the sample of psychiatric patients they studied by whether they had previously tried to kill themselves or not.

You can find out more about this research at

http://www.sciencedaily.com/releases/2010/06/100615105249.htm?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+sciencedaily+%28ScienceDaily%3A+Latest+Science+News%29&utm_content=Google+Reader

SHANK2 gene linked to learning disabilities and autism

Variations in a gene called SHANK2 could be linked to both learning disabilities and autism. Researchers from Heidelberg University Hospital studied 396 people with autism and 184 with learning disabilities. They found more variations in the gene in people with learning disabilities and autism none of which were present in an unaffected control group. The gene is partially responsible for linking nerve cells together via synapses.

You can find out more about this research at

http://www.sciencedaily.com/releases/2010/05/100525103933.htm?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+sciencedaily+%28ScienceDaily%3A+Latest+Science+News%29&utm_content=Google+Reader

Dozy drinkers less likely to be drunkards

People who feel sleepy after a few drinks might be less likely to develop an alcohol problem. A gene called ADH1B*3 is associated with a lower risk of alcoholism and is found almost exclusively in people with African ancestry. Researchers from the University of Missouri studied 91 African Americans between 21 and 26. Some of them had the ADH1B*3 gene while others didn't. The participants were given a moderate amount of alcohol and those with the ADH1B*3 gene were more likely to have higher levels of sedation and a raised pulse rate. The researchers though that people with the gene might be less likely to drink if it made them feel sleepy rather than stimulated or disinhibited, or, if they are like me they might just fall asleep before they drink too much!

You can find out more about this research at

http://www.sciencedaily.com/releases/2010/05/100504162805.htm?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+sciencedaily+%28ScienceDaily%3A+Latest+Science+News%29&utm_content=Google+Reader

New gene added to schizophrenia risk factors

Although there is no single 'gene for schizophrenia' some genes are known to raise people's risk. Researchers from the Universite de Montreal have carried out a detailed analysis of a large database of patients and added another gene to the list - SHANK3. The gene has previously been linked to autism and is involved in maintaining the physical structure of nerve cells. Mutations in the gene result in abnormalities in cell shapes - abnormalities that have been observed in some schizophrenia patients.

You can find out more about this research at

http://www.sciencedaily.com/releases/2010/04/100412151825.htm?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+sciencedaily+%28ScienceDaily%3A+Latest+Science+News%29&utm_content=Google+Reader

More research on genes and autism

A study co-authored by Ning Lei from Princeton University has shed a little more light on the genetics of autism. The study compared 943 families who had children diagnosed with autism with 6,317 unaffected people and looked at the prevalence of 25 gene mutations. It identified two additional genes that could be linked to autism, one of which, NCAM2, affects the hippocampus, a brain region previously associated with the condition. A lot of the genes implicated in autism are known to affect the synapse - the link between brain cells.

You can find out more about this research at

http://psychcentral.com/news/2010/05/03/new-evidence-on-autism/13423.html

New gene linked to Alzheimer's risk

Researchers from the University of Miami have identified a new gene associated with an increased risk of developing Alzheimer's disease. In a study of 5,376 people, 2,269 of whom had Alzheimer's disease, the researchers compared a stretch of genes to see if certain variations were more common in the people with Alzheimer's. They found that a gene called MTHFD1L on chromosome six was associated with a doubling in the risk of developing late-onset Alzheimer's. The gene is known to be involved in influencing the body's levels of a substance called homocysteine, high levels of which are known to be a strong risk factor for late-onset Alzheimer's diseases.

You can find out more about this research at

http://www.sciencedaily.com/releases/2010/04/100414083305.htm?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+sciencedaily+%28ScienceDaily%3A+Latest+Science+News%29&utm_content=Google+Reader

Obesity, genes and Alzheimer's disease

FTO is a gene associated with obesity. People with one copy of it are on average 1.5kg heavier than average and people with two copies of it are 3kg heavier. The gene is carried by 46% of Western Europeans and researchers from California University now think it may also be associated with Alzheimer's disease. The scientists found that those people with the variation had 8% fewer cells in the frontal lobe of the brain and 12% less in the occipital lobe - areas associated with complex judgments and the processing of mental imagery respectively. Obesity increases the risk of dementia because it can lead to damage to the blood vessels in the brain, in turn leading to damage to brain cells but the differences could not be attributed to cholesterol levels, diabetes or high-blood pressure.

You can find out more about this research at

http://www.telegraph.co.uk/health/healthnews/7608210/Obesity-gene-may-also-cause-Alzheimers.html

Another study into the links between genetics and Alzheimer's disease, also carried out by researchers at the University of California looked into the effect of variations in a gene called Catechol-O-Methyltransferase (COMT). A sample of 2,858 African-American and Caucasian people between the ages of 70 and 79 were studied over an eight-year period. Their DNA was analyzed and they were tested on their language, concentration and memory, response time and attention. People with the 'Met' variant of the gene experienced a greater decline in their thinking skills over the years while people with the 'Val' variant scored, on average, 32% better if they were Caucasian and 48% better if they were African-American.

You can find out more about this research at

http://www.sciencedaily.com/releases/2010/04/100419162119.htm?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+sciencedaily+%28ScienceDaily%3A+Latest+Science+News%29&utm_content=Google+Reader

Linking the Big Five to depression

Psychologists often use the 'Big Five' or OCEAN model to assess people's personality on five variables: Openness, Conscientiousness, Extraversion, Agreeableness and Neuroticism (the tendency to see events in a negative or pessimistic light). Previous research has linked extraversion to a decreased risk of depression and neuroticism to an increased risk but there has been little or no research into all five factors. Researchers from Virginia Commonwealth University in Richmond, Virginia studied 44,112 people including 542 pairs of twin - something which allowed them to explore the links between personality type, genetics and depression. They found that neuroticism was the most-important personality factor in influencing the link between genetics and depression. The next most important factor was conscientiousness - the less conscientious people were the more likely they were to become depressed. Openness, extraversion and agreeableness all had less of an influence.

Kendler, K.S. and Myers, J. - The genetic and environmental relationship between major depression and the five-factor model of personality Psychological Medicine May 2010, 40(5), 801-806

Genes and autism

Anthony Monaco from the Wellcome Trust Centre for Human Genetics at Oxford University and a team of international researchers have been looking into the links between genes and autism in a study of 661 families in the U.K., the Netherlands, Italy and Germany. The team looked at four genes they thought might be linked to autism and found that two - LRRN3 and LRRTM3 - were significantly associated with susceptibility to autism. LRRN3 is thought to play a role in the development and maintenance of the nervous system while LRRTM3 is thought to be involved in organising the connections between brain cells.

You can find out more about this research at

http://www.sciencedaily.com/releases/2010/03/100325102415.htm?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+sciencedaily+%28ScienceDaily%3A+Latest+Science+News%29&utm_content=Google+Reader

Tobacco, drug use and genetics

Around 60% of adolescents have smoked a cigarette at some point in their lives and around a third have smoked during the last month. Tobacco is often seen as a gateway to cannabis and other drugs but some scientists dispute this 'gateway' theory and suggest that there is a common genetic factor that links tobacco smoking and cannabis use. Researchers from the University of Amsterdam studied 3,744 Finnish twins and found that the 'total variation in the initiation of illicit drugs' was down to starting smoking (40%) genetic factors (32%) common environmental factors (20%) and unique environmental factors i.e. factors experienced by only one of the twins (8%) suggesting that tobacco use was marginally more important than genetics in predicting illegal drug use.

Huizink, Anja C. ... [et al] - Tobacco, cannabis, and other illicit drug use among Finnish adolescent twins: causal relationship or correlated liabilities Journal of Studies on Alcohol and Drugs January 2010, 71(1), 5-14