Hallucinations are a positive symptom, in most cases the
hallucinations suffered by schizophrenics are not the usual visual
hallucinations I would imagine most people experience when ill with a
temperature. The most common hallucinations in schizophrenics are
auditory hallucinations, usually consisting of one or more voices,
which may speak to them directly, but quite often the voices are not
directed to them, but do concern them, usually in a derogatory way,
making suggestions to harm themselves or others, criticizing, or
giving a running commentary on their own thoughts and actions.
Hallucinations can involve any of the senses, such as visual,
olfactory and tactile hallucinations, but auditory are the most common
in schizophrenics .

Delusions, which are false irrational beliefs, not based on reality,
can take many forms, the schizophrenic may be deluded that they are
more powerful or important than any other human, that they have god
like powers or knowledge, they may believe they are a person from
history; these delusions are referred to as delusions of grandeur
They may experience paranoid delusions, that they are
being persecuted and that someone or something is conspiring against
them, or trying to harm them.

Negative symptoms include flattened emotional response, where almost
no stimuli will provoke an emotional response; they will continue to
speak in a flat toneless voice, this affect appears to only affect a
schizophrenic's external emotional appearance and not their internal
emotions and feelings. schizophrenics may suffer with
poverty of speech and be restricted in the spontaneity and information
in their speech Schizophrenics may suffer with
anhedonia, an inability to experience any pleasure from activities
that may have previously been pleasurable, leading to a lack of
interest in recreational activities. They fail to develop close
relationships and become socially withdrawn; they lack social skills
and lack an interest in being with people. The schizophrenic may find
that they lack energy and motivation and have no interest in the way
they look and their personal hygiene.

Disorganised symptoms include bizarre behaviour, thought disorders and
disorganised speech. Irrational and disorganised thoughts are probably
the most important symptoms of schizophrenia, they will have
difficulty in organizing their thoughts, and find
it difficult to sort out from logical thoughts and non logical
thoughts that any non schizophrenic would know where unreal and
ridiculous

Thought possession or insertion, the schizophrenic patient believes
that thoughts are not his own and are being placed in his mind by
someone or something else such as aliens or god. Thought withdrawal,
Schizophrenic patients may also believe that their thoughts are being
removed by some kind of phonological machinery, aliens or God and that
these thoughts may be broadcast or read by others. The schizophrenic
patient may also suffer with thought blocking, where they may have a
thought, and be talking about it, and then suddenly stop and not
remember what they were saying or thinking. They
may have problems with learning and will find it harder to concentrate
whilst reading or watching television.

A schizophrenic whilst in conversation will change from one subject to
another, Words may take on special meanings to them, either because
they trigger private associations or because they pay particular
attention to individual sounds rather than whole words for example
'Psychiatry' Might be heard as 'sigh kaya tree' so the schizophrenic
will change the subject from psychiatry to mystical trees
also they may avoid some words because they sound abusive or evil. A Schizophrenics
speech may seem incomprehensible to a non schizophrenic; they will
make up meaningless words, or use words which rhyme rather than making
any sense .

Schizophrenics seem to lack the ability to behave in a socially
acceptable way, they may collect and hoard items, sometimes even
rubbish, some dress in a strange way and some are known to behave in a
childlike manner or even behave in a sexually inappropriate way.

Symptoms that don't seem to belong to the three categories such as
catatonia, which is a motor symptom, such as positioning themselves
into a strange bodily position and remaining motionless and waxy
flexibility, where their limbs can be molded into
position like a statue and remain motionless for a long period of
time. Negativism, which is resisting attempts and suggestions, for no
apparent reason, to move or be moved or doing the exact opposite to
what is requested. A patient with ambitendence
will begin a movement such as going to shake a persons hand and then
appear to change their mind and take the hand back
Echopraxia, constant mimicking of a person when requested not to.
Stereotypies, regular repetitive movements for no apparent reason
'e.g. moving the arm backwards and outwards repeatedly while saying
'but not for me'.

Abnormalities found in the brains of schizophrenics may be due to
genetic factors or due to the effects from environmental factors,
studies have found that the lateral ventricular in a
schizophrenic patient is around 25% larger than normal, although their
actual brain is fractionally smaller and has a reduced cortical volume
mostly in the temporal lobes, basal ganglia and limbic structures and
also sulcal widening. It has been found that
schizophrenic patients have structural faults in the temporal cortex,
hippocampus, basal ganglia and the prefrontal cortex which also has a
reduction in grey matter and a slow metabolic rate. It has been
suggested that during the second trimester of the foetal development
that there is some failure in neuronal migration.

The largest risk factor for developing schizophrenia is genetic. The
main studies on twins by Gottesman show that monozygotic twins
have a greater risk at 48% of both developing schizophrenia compared
to dizygotic twins which have 17% chance of developing
schizophrenia, although this can not be proved
without doubt because monozygotic twins would be treated similarly by
parents and would share the same environmental influences Adoption
studies backup the theory Tienari studied
155 adopted children whose natural mothers were schizophrenic. When
followed up years later he found that 10.3% had developed
schizophrenia, compared with only 1.1% of those without schizophrenic
mothers. Parnaset backs up this theory; he studied 207 children
with schizophrenic mothers and followed them up nearly 30 years later
16% developed schizophrenia compared to a low risk group which only 2%
developed schizophrenia . Evidence has been found
by Sherrington et al of a group of genes on chromosome 5 that
might be the reason for a person being susceptible to developing
schizophrenia, but it has yet to be confirmed .

The symptoms of schizophrenia are so varied from self neglect and
social withdrawal, to delusions and hallucinations, and not all being
present in every case. The wide range of abnormalities in the brain
could possibly explain why there is such a wide range of symptoms.
Considering all of the genetic and environmental factors that play a
role in its occurrence research seems to point towards genetics being
the main factor and environmental factors playing a part in triggering
the onset of schizophrenia.