Depression is becoming one of the leading causes of absenteeism in western
countries.
So what is mental illness? It is "any diagnosable mental, behavioural,
or emotional disorder that interferes with or limits a person's ability to live,
work, learn, and participate fully in his or her community", according to
the US Substance Abuse and Mental Health Services Administration.
Stress and substance abuse can trigger mental illnesses.
There are over 200 kinds of mental illness. Among the most serious are
psychotic disorders in which a person loses touch with reality, such as
schizophrenia and other delusional disorders.
Schizophrenia affects about 1% of the population and usually manifest in
males between the ages of 15 and 25 years and in females between 25 and 35
years, according to Dr Yusuf Moosa, senior psychiatric specialist with
Gautengs Community Mental Health department.
Its symptoms include hallucinations (hearing voices and seeing visions),
delusions (fixed, false beliefs) and bizarre or disorganised behaviour and/or
thoughts.
A less serious delusional disorder may involve an otherwise normal person
holding one fixed delusion, such as a pathologically jealous man who is
convinced his partner is unfaithful to him.
Mood disorders include depression and bipolar mood disorders. Depression can
lead to suicide. Bipolar disorder (manic depression) is when a person fluctuates
between being depressed and feeling very high or manic. In the manic phase, the
persons thoughts are rapid and tend to overwhelm them. They tend not to sleep
and to have periods of rapid but non-productive activity. In this phase, the
person may have grandiose delusions about possessing special powers, and are
often very irritable.
Bipolar disorder requires life-long therapy on mood stabilisers.
The diagnosis of mental illness is sometimes not clear cut, with some
disorders "blurring" into one another, says Moosa, who is also a
senior lecturer in the psychiatric department at Wits University.
Personality disorders are often more difficult to manage.
"Everyone is born with a temperament and this becomes their personality
over time," says Moosa.
While most of us have some personality traits, these become disorders when
they impact and become a problem for the people around them. I t usually also
affects the individuals social and occupational functioning.
Some examples of personality disorders are:
- Paranoid: people who tend not to trust anyone
- Schizoid: withdrawn and asocial people who often relate better to animals
than people
- Histrionic: melodramatic people who have frequent histrionics
- Antisocial: psychopaths who deceive, manipulate and have no concern for
others
- Borderline: those for whom everything is seen in extremes of either good
or bad
- Narcissistic: who think they are the best
- Dependent: people who cannot make any decisions on their own
- Obsessive-compulsive: those who are very meticulous and orderly about
everything.
Unfortunately, says Moosa, many people do not seek psychiatric help because
they dont want to be seen as "crazy".
However, many mental illnesses can be treated with drugs that act on
neurotransmitters in the brain and with psychological counselling.
 
Signs of mental illness
The outward signs of a mental illness are often behavioural. 
Individuals may be extremely quiet or withdrawn or may burst into tears or have
outbursts of anger. The following are signs that your loved one may want to
speak to a medical or mental health professional.
In adults:
- confused thinking
- prolonged depression (sadness or irritability)
- feelings of extreme highs and lows
- excessive fears, worries and anxieties
- social withdrawal
- dramatic changes in eating or sleeping habits
- strong feelings of anger
- delusions or hallucinations
- growing inability to cope with daily problems and activities
- suicidal thoughts
- denial of obvious problems
- numerous unexplained physical ailments
- substance abuse
In older children and pre-adolescents:
- substance abuse
- inability to cope with problems and daily activities
- change in sleeping and/or eating habits
- excessive complaints of physical ailments
- defiance of authority, truancy, theft, and/or vandalism
- intense fear of weight gain
- prolonged negative mood, often accompanied by poor appetite or thoughts of
death
- frequent outbursts of anger
In younger children:
- changes in school performance
- poor grades despite strong efforts
- excessive worry or anxiety (i.e. refusing to go to bed or school)
- hyperactivity
- persistent nightmares
- persistent disobedience or aggression
- frequent temper tantrums
(From the US National Mental Health Association)