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Left-handed people have an average income of about 10% lower than right-handed people, according to a recent study by Harvard University. And yet, they also face a higher risk of mental illness and developmental disorders.

>>>Left-handed geniuses

Left-handed people are always targets of discrimination, gossip, curiosity and fear for centuries. However, the scientific community is now recognizing the scientific importance of understanding why people often use this hand instead of the other hand for activities such as writing, grasping, eating or tossing balls. . The tendency to use only one hand for most day-to-day activities has opened the opportunity for experts to explore how the human brain is programmed and connected.

Since then, scientists have been able to find ways to study disorders related to brain development, such as dyslexia, schizophrenia and ADHD syndrome (hyperactivity disorder). In particular, these diseases often appear in left-handed people.

There are many rumors surrounding people's hands

The results of a recent study conducted by Central Swedish University show that people who use both hands in daily activities and who do not have the right hand face a higher risk of ADHD compared to those who agree. left hand.

The number of left-handed people accounts for about 10% of the population, according to The Wall Street Journal, citing experts. Meanwhile, there is only about 1% ambidextrous. The reason why a person doesn't like to use his right hand is partly due to heredity. Even in identical twins, which are 100% homologous, are not always on the same hand.

What matters most is the environmental factors, especially stress, while still in the fetal stage. For example, children born to mothers who are older or light-weighted at birth are more likely to be left-handed. And mothers who face too much psychological pressure during pregnancy can often give birth to a non-right-handed child.

A 2009 study on Neuropsychologia published an estimated 25% of the positive hand difference is due to genetic predisposition. Studies of Northwestern University (USA), University of Aarhus (Denmark) also made similar comments about the correlation between the condition of the fetus and the propensity to move after the mother's heart.

On average, there is no clear difference in IQ between left-handed and right-handed people, despite common human notions. There is some evidence that left-handed people are better in terms of inference, or starting with an existing knowledge to develop entirely new concepts, which are considered elements of creativity.

Left-handed people account for only 10% of the total population, about 20% of people with schizophrenia are left-handed.

Relationships between left-handed and difficult reading or ADHD as well as other mood disorders have been identified in some previous studies.

The cause of these relationships is still not scientifically defined. Experts suspect that it may be related to a concept called hemispheric theory. The brain has two parts. Each half performs different functions, as the main language handling usually takes place in the left hemisphere. In right-handed people, the left brain plays a key role. However, this trend does not really happen to left-handed people.

About 70% of left-handed people still rely on the left hemisphere to place language processing centers, a major function of the brain, according to Metten Somers, an expert in psychiatry at Utrecht University (Netherlands). . The remaining 30% relies on the right hemisphere or evenly divides activity on both hemispheres, and this group is at high risk of problems with mental disorders and brain development.