# Developmental psychology/Chapter 7/A Healthy Time

Different from infancy and adolescence, "middle childhood" is the healthiest part of your life thanks to the slow and steady impact of nature and nurture:
* Children gain 2 inches and 5 pounds a year.
* The death rates for 5-9 yrs old is the lowest. At this point, genetic diseases have already taken place/not present, immunization takes place and car accidents are the lowest.
* The death rates have decreased for this age group because of medicine/injury prevention: In the USA, the death rate for 5-14 yrs old was 60/100k. Now, it's less than 13 (2015).
* 70% of US children had really good teeth when going for an oral examination.
Peers and parents are the main factors when encouraging healthy habits. These should be implemented before the "rebellious" teenager phase. Sports are a really good part of a child's life, allowing children to be physically and emotionally healthy. But with everything comes risks, as children can be injured - for example, American football has implemented regulations for 7-8-year-olds so they do not get a brain injury.
Although many parents put their kids in after-school sports programs for whatever sport they chose, children from low-SES families/disabled don't get this equal opportunity. A correlation has been established where decreased playing time = decreased educational performance. In Japan, children score higher in international tests and live longer because of the country's emphasis on exercise.
So how does exercise improve cognitive function?
* Cerebral blood flow increases
* Better moods = better mentality
* Children learn, then they do [show what they know by doing it] (learn to handwrite = learn to read).
At age 7, selective attention improves (focusing on certain stimuli and canceling out distractions). This is because of cognitive maturation and social play (playing soccer, you must focus on the ball and ignore other stimuli). Thanks to increasing myelination over the years, the reaction time improves throughout childhood - which is the time it takes for a child to react to stimuli.

## Health Issues

Not everyone is fortunate enough to go disease-free. Childhood overweight is a BMI >85th percentile, while childhood obesity is a BMI >95th percentile. In North America, childhood obesity has >doubled since 1980. Except for 2-5 yr olds, childhood obesity has been slowly increasing in the US. From 1991-2011, overweight in 6-12 yr olds has gone up from 11% to 26% in China. American diets are practically not healthy, showcasing that obesity in immigrant children in the US increases.
Obviously, many consequences of obesity exist, including asthma, blood pressure, and bad cholesterol increases. Obesity also affects individuals mentally, as school performances and confidence decreases.
2016 stats
* 18% of US 6-11 yr olds were obese
* 14% of US 2-5 yr olds were obese

### Asthma

Asthma is a chronic respiratory disease where the ability to breathe is hampered by inflammation, which may lead to frequent hospital trips during asthma attacks. Asthma, if developed into adulthood (does so half of the time), can be fatal. Asthma impairs social skills and learning ability in school due to frequent absences. 1/10 US 5yr-11yr suffers from asthma. Rates increase as family income decreases.
Causes for asthma are a combination of multiple things, such as "genetic sensitivity to allergies", various respiratory diseases, and compromised functioning of the lungs. A hygeine hypothesis suggests that children need to be exposed to smaller infections and allergic sources in order to build immunity. This is supported because
* "First-born children develop asthma more often than later-born" children
* Children who live on farms experience fewer allergies and asthma rates
* Children born through C-section tend to develop asthma
* A possible change in microbes (diets, drugs, animals) could treat the disease, but no one thing causes it.

## Cultural play

Although obesity is somewhat genetic, culture also plays a role. How come Asian American girls are less obese compared to boys? How come African American girls weigh more than boys? Parenting also plays a role. Obesity is likely to increase if the child is born too early, watches a lot of TV, and rarely plays outside. Children may also pester their parents to buy whatever foods they like, including the sugary cereal they say on the television.
A treatment requires a multi-step approach, including parental/child education, reforming school lunches and TV ads, and tailors to the individual differences of the child.