1. Anxiety Disorder : Specific Phobia --> A specific phobia, formerly called a simple phobia, is a lasting and 
unreasonable fear caused by the presence or thought of a specific object
 or situation that usually poses little or no actual danger. Exposure to
 the object or situation brings about an immediate reaction, causing the
 person to endure intense anxiety or to avoid the object or situation entirely.
 
Symptoms:-
- Excessive or irrational fear of a specific object or situation.
 
- Avoiding the object or situation or enduring it with great distress.
 
- Physical symptoms of anxiety or a panic attack, such as a pounding heart, nausea or diarrhea,
 sweating, trembling or shaking, numbness or tingling, problems with 
breathing (shortness of breath), feeling dizzy or lightheaded, feeling 
like you are choking.
 
- Anticipatory anxiety, which involves becoming nervous ahead of
 time about being in certain situations or coming into contact with the 
object of your phobia. (For example, a person with a fear of dogs may 
become anxious about going for a walk because he or she may see a dog 
along the way.)
 
Requirements for diagnosis:- 
The doctor will begin an evaluation by performing a complete medical 
history and physical exam. Although there are no lab tests to 
specifically diagnose specific phobias, the doctor may use various tests
 to make sure that a physical illness isn't the cause of the symptoms. If no physical illness is found, the patient is referred to a 
psychiatrist or a psychologist. Psychiatrists 
and psychologists use specially designed interview and assessment tools 
to evaluate a person for a specific phobia.A specific phobia is diagnosed if the person's fear and 
anxiety are particularly distressing or if they interfere with his or 
her daily routine, including school, work, social activities, and 
relationships.
Causes:-
The exact cause of specific phobias is not known, but most appear to be 
associated with a traumatic experience or a learned reaction. Fear can be learned from others, as well. A child whose parents react 
with fear and anxiety to certain objects or situations is likely to also
 respond to those objects with fear.
Risk-Factors:- 
Environmental factors --> 1)
 Direct exposure to a traumatic event.
2) Witnessing a traumatic event. 
3)Hearing or reading about dangerous situations.
 
Psychological factors-->  it is common for individuals with
        specific phobia to have distortions regarding memories
        that involve the phobic stimulus. They recall the phobic
        situation as more dangerous than it really was, or the
        feared animal larger, faster, or more aggressive than it
        was in reality. The memory distortions can be supported
        by impaired beliefs and interpretations attributed to
        feared objects or situations. The anxiety response
        experienced during a phobic situation can be maintained
        or increased by these impaired beliefs and
        interpretations.
Biological
        factors--> Although there is relatively little research conducted on
        the biological factors of specific phobia, there is
        evidence that specific phobia tends to run in the family.
Affective Disorder: Major Depressive Disorder
Symptoms:-
- Feelings of helplessness and hopelessness. .
 
- Loss of interest in daily activities. .
 
- Appetite or weight changes. 
 
- Sleep changes. 
 
- Anger or irritability. . 
 
- Loss of energy. . 
 
- Self-loathing. 
 
- Reckless behavior. 
 
- Concentration problems. 
 
- Unexplained  aches and pains. 
 
Requirements for diagnosis:- 
Mental health professionals may administer a screening test such as the 
Beck Depression Inventory or the Hamilton Rating Scale, both of which 
consist of about 20 questions that assess the individual for depression.
 However, most mental health professionals generally diagnose depression
 based on symptoms and other criteria.
Causes:- 
Genetic, biological, and environmental factors can contribute to its development.Currently, it appears that there are biochemical causes for depression, occurring as a result of abnormalities in the levels of certain chemicals in the brain.
 
Risk-Factors:-  
Statistics show that the children of parents who suffer from depression 
are more likely to develop the disorder themselves. A person has a 27% 
chance of inheriting a mood disorder from one parent, and this chance 
doubles if both parents are affected.  Studies of the occurrence of 
depression in twins show a 70 percent chance for both identical twins to
 suffer from depression, which is  twice the rate of occurrence in 
fraternal twins.Depression is more common in people who have a history of trauma, sexual abuse, physical abuse, physical disability, bereavement at a young age, alcoholism, and insufficient family structure.Fifty percent of people with major depressive disorder experience their 
first episode of depression at about age 40, but this may be may be 
shifting to the 30s.  Studies find that the rate of incidence is higher 
among middle-aged people.   Major depressive disorder affects 10% of men and 20% of women.  Hormonal
 differences may put women at a higher risk for depression.  Hormone 
levels are influenced by pregnancy, and many women experience depression
 after giving birth.