Adolescence is the stage of life between childhood and adulthood, ranging from 10 to 19 years. It is a distinct period in human development and crucial for setting the groundwork for long-term health. Teenagers grow quickly in terms of their physical, cognitive, and emotional development.In the body of teenagers, major changes in microorganisms take place. With the development of these changes in the microbiome of teenagers, diseases are also developed. Teenagers are the future of the world. Microbiota and diseases have an impact on their emotions, thoughts, decisions, and interactions with others and their environment. This chapter is written to acknowledge the readers about the resident microorganisms of the human body during adolescence and the many kinds of changes that occur in the microbiome due to lifestyle changes.

Adolescence includes phases of both significant social role shifts and biological growth, both of which have evolved over the previous 100 years. A relatively prevalent neurologic condition throughout adolescence is epilepsy. Growth, hormonal, psychological, and social circumstances all undergo significant change during adolescence. It can be extremely challenging for many young women with epilepsy to manage the developmental and emotional challenges of adolescence while still having to deal with the reality of seizures, medication, stigma, and restriction. These young women's everyday functioning and quality of life are further impacted by the additional load of comorbidities like depression. It is crucial to spend time with these teenagers discussing the effects of epilepsy and giving them the information and resources they need to succeed in regaining their confidence and control over their lives. Teenagers frequently struggle to embrace the chronic nature of their epilepsy and to take their medications as prescribed, which can lead to bodily harm and real or imagined barriers to employment and lower morale. Additionally, it was discovered that children and teenagers with epilepsy are more likely to exhibit depressive and anxious symptoms. Additionally, teenagers also suffer from other neurological disorders that are common but less reported, like multiple sclerosis. The aim of this chapter is to focus on some of the neurological diseases that are present mainly in the adolescent period mainly epilepsy and some other neurological diseases. 

The lifestyle is the standard of living, conduct, and practice of an individual person or a set of people that are usual or are selected by them. Lifestyle is a culture based on the living conditions, and the conduct of a person is determined by ethnographic factors and the individual temperament of a person. Oral diseases are closely related to lifestyle. Oral hygiene can be maintained by innocuous choices in relation to food, smoking tobacco, and the usage of dental health services. The changes in lifestyle have disturbed the balance of the metagenome of the microbiota and human host. This section examines the role of various factors in dental health, including lifestyle and behavioral factors.

Lung exposure to airborne toxins from various sources in the environment can lead to acute and chronic pulmonary or even systemic inflammation. The environment contains several compounds that might irritate the respiratory system, including heavy metals and agrochemicals in adolescents. Toxicants can induce respiratory illnesses and airway inflammation, which alters either the structure, function, or composition of the body. Because of their long-term physical development, the developing immune and respiratory systems are particularly vulnerable to various environmental toxins. They promote the accumulation and activation of several allergy indicators (eosinophil count, IgE, and numerous cytokines), which may be used to potentially trigger lung inflammation. This chapter describes the impact of various toxic substances on the airway and pulmonary system. Also, we have covered specific pulmonary toxins, toxicants, and toxin combinations. The concluding section of the chapter emphasizes raising awareness of the dangers and adverse effects toxicants may have on health as well as encouraging more efforts to reduce exposure to adolescents. Metropolitan residents use pesticides for the prevention of mosquitoes, ticks, ants, and cockroaches. Reducing indoor allergens and pollution can lower asthma treatment costs and severity.

Cancer may become the cause of death due to lifestyle changes among adolescents. It is becoming widely understood that our lifestyle choices have a big impact on our likelihood of getting cancer. Numerous unavoidable risk factors are responsible for most malignancies; however, to lower the likelihood of getting cancer, we may alter our lifestyle. Having a balanced diet, controlling your weight, exercising regularly, abstaining from alcohol, and avoiding tobacco use are all examples of healthy lifestyle choices that can reduce your risk of acquiring cancer. Using information from human research, we give data in this chapter on the correlation between specific lifestyle factors and their contribution to the development of prostate, breast, colon, and lung cancers.

The outlook of present-day adolescents’ lifestyles is certainly the outcome of unhealthy childhood. The consequences of it are leading adolescents to hypertension and cardiovascular diseases. There are several contributing elements to the complicated and varied conditions of hypertension. Hypertension is increasing consistently in children and may persist into adulthood. Cardiovascular problems are heart-related issues such as cardiac conditions, stroke, endocarditis, irregular heartbeat, and more. Cardiovascular diseases are the main complications caused by hypertension. Weight control, lowered blood pressure, enhanced emotional wellness, and a propensity for more physical activity in maturity are all health advantages of an active lifestyle for teenagers. The possibility to stratify cardiovascular disease risk is the main justification for detecting high blood pressure in most children and adolescents in the future. The studies have shown enough evidence of anatomical and functional alterations in the cardiovascular system that signify early atherosclerosis in youth. According to clinical research, numerous variables that contribute to hypertension interact with one another, negatively impacting the cardiovascular system in people.

Due to vascular blockage, cardiovascular disorders can cause hemorrhagic or ischaemic disorders in the heart, brain, and other sections affecting vascular tissue. Basic clinical manifestations can no longer be utilized as a standard characteristic to assess individuals who have acute coronary atherosclerosis, hypertension, and cardiovascular disease. Due to arterial blockage, cardiovascular disorders can cause hemorrhagic or ischemic conditions in the heart, brain and other vascularly connected tissues. Teenagers' heavy consumption of alcohol and cigarettes, overweight or obese, diabetes, hypertension, hyperlipidemia, and other risk factors are the primary cause of cardiovascular disease in adults. Hypertension has a major negative impact on patients' health, which is directly tied to the prevalence of cardiovascular disease. This paper aims to emphasize the outcomes of an unhealthy adolescent lifestyle that consecutively leads to lifestyle-associated problems, especially hypertension and cardiovascular issues. The studies help give a precise output of the analysis of what preventive measures need to be taught to adolescents for a healthier and better future.

The medical professional continues to see a lot of adolescents with gastrointestinal illnesses, which have a big emotional and financial toll. One cannot overstate how crucial it is to identify gastrointestinal disorders correctly. Diseases like Lactose intolerance and Celiac disease cause nutrition deficiency among many adolescents. Gastrointestinal disorders are illnesses that comprise a variety of chronic or recurrent symptoms that cannot be fully explained by structural or biochemical research at this time. One cannot overstate the significance of correctly diagnosing gastrointestinal diseases in children. Children and their parents need to be aware that their diagnosis is not only psychological but also medical. The physiological and psychological factors that contribute to symptom manifestation must be considered throughout management and therapy. The chapter focuses on illnesses that affect adolescents, including appendicitis and ailments of the colon, rectum, small and large intestines, and stomach. 

An adolescent with diabetes faces very different challenges than a young adult or grownup with diabetes. Failure to acknowledge and address this will result in noncompliance and absence from the clinic. Type I diabetes is the most prevalent metabolic illness in childhood and adolescence, although Type II diabetes in adolescents is frequently associated with obesity, which may contribute to these increased risks. Obesity impairs the body's capacity to utilize insulin, resulting in elevated blood sugar levels. Among younger people, early identification of type II diabetes as well as dedication to controlling overweight and obesity are critical. As a result, a number of people with diabetes mellitus who have had it for a long time experience chronic and recurrent clinical symptoms related to the disordered motility of almost the entire GI tract, such as esophageal and epi-pharyngeal dysphagia, gastroparesis, constipation, diarrhea, and fecal incontinence. Dietary changes are one of the therapeutic methods used to treat chronic recurrent symptoms caused by autonomic dysfunction. Dietary manipulations and several medications, including dopamine antagonists, antibiotics, and hormones, promote peristalsis. On the other hand, gastrointestinal symptoms related to acute metabolic problems are self-limited and resolve quickly after the normal metabolic environment has been restored.

Among women of reproductive age, polycystic ovarian syndrome (PCOS) is one of the most prevalent endocrinological diseases. It is a metabolic and endocrine disorder in women that affects hormone levels. PCOS comes with many comorbidities, which include obesity, which has been associated with an increased risk of cardiovascular disease, diabetes, and metabolic abnormalities, as well as a reduced response to reproductive therapy such as laparoscopic ovarian diathermy, gonadotropins, and clomiphene citrate. Genetic, dietary modification, lifestyle, and obesity play an important role in causing PCOS in women. Women with PCOS are more likely to have mood disorders than other women, including bipolar disorders, depression, and anxiety, and worse quality-of-life ratings. Adolescent growth and wellbeing are significantly impacted by depression. Studies have shown that women with PCOS are more likely to have increased carotid intima-media thickness and elevated coronary artery calcium scores. Menstrual abnormalities, increased androgen symptoms, and infertility are all improved by losing weight. Management of clinical manifestations of PCOS includes oral contraceptives for menstrual irregularities and hirsutism. Recent data suggest that proper diagnosis and management of PCOS are essential to address patient concerns and prevent future metabolic, endocrine, psychiatric, and cardiovascular complications. 

Controlling communicable diseases has long been a priority for international health policy. The burden and mortality of communicable diseases have significantly decreased among children under the age of five, but older children and adolescents are subject to greater disease burden, and it is unclear whether current policies and programs continue to be in line with intervention targets. There is compelling evidence that suggests bacteria have a role in a number of chronic, non-infectious disorders, including coronary heart disease, neurological disorders, and a few types of cancer. Teenagers all around the world suffer from various diseases caused by microorganisms. The diseases are caused due to the change in lifestyle. Amidst tremendous physiological change and growth, the young adult is exposed to a range of stressors and environmental factors. Diseases like tuberculosis, urinary tract infection, candidiasis, influenza, and AIDS are very common among adolescents and affect millions of teenagers across the world. Some of the diseases like sexually transmitted illness, Ringworm, and Mononucleosis are very alarming for adolescents as most of the teens across the world are suffering at a staggering rate. This chapter is written to inform the readers about the common diseases caused by microorganisms in the teenage years due to lifestyle changes. 

Millions of lives are saved annually thanks to vaccination, which is a success story in global health and development. More than 20 deadly illnesses are prevented by vaccines, allowing individuals of all ages to enjoy longer, healthier lives. Currently, vaccinations stop 3.5-5 million fatalities every year from illnesses including measles, diphtheria, tetanus, pertussis, and influenza. Diseases that used to often damage or kill infants, children, and adults have significantly decreased because of vaccinations. Immunization offers protection not just against the disease but also against any potentially harmful side effects or sequelae. A global danger to development and health is antimicrobial resistance (AMR). Among the top 10 worldwide public health risks to humanity as per WHO, is AMR. Drug-resistant infections are mostly brought on by the improper use and abuse of antibiotics. The proliferation of bacteria, some of which may be resistant to antibiotic therapy, is encouraged by a lack of clean water, proper sanitation, and effective infection prevention and control. The economic burden of AMR is substantial. Long-term disease not only increases the risk of mortality and incapacity but also lengthens hospital stays, necessitates the use of more expensive medications, and puts a strain on the finances of those affected. In this chapter, we discussed the vaccination programs and adolescents' risk of antimicrobial resistance as one of the major future aspects to be followed by parents of teenagers. Teenagers are the future of the world. Microbiota and diseases have an impact on their emotions, thoughts, decisions, and interactions with others and their environment.