Psychiatric diseases are quite different from other diseases of body. Some very important symptoms of these illnesses are:
Hallucinations are sensory perceptions without any sensory input. Most common hallucinations are visual, auditory, tactile and olfactory hallucinations.
- In visual hallucinations, person sees objects not present.
- In auditory hallucinations, person hears voices not present.
- In tactile hallucinations, person feels bugs crawling over the body.
All perceptions are not actually present. There is no sensory input.
There is sensory input. That input is wrongly perceived and misinterpreted. Typical example is of rope, perceived as a snake.
Delusions are false beliefs of person held very strongly and are impervious to reasoning. E.g. person may perceive another person as enemy without any reason.
Form of delusion that develops slowly. It is concerned with belief of patient. E.g. if person is paranoid and hears laughing of a group of people in next room, he may assume that the group is laughing at him.
Irrational thoughts and acts which are compulsive in nature and occur repeatedly. The person cannot get rid of it. E.g. person washes hand again and again.
Psychiatric categories are often imprecise and broad divisions are made on the basis of predominant manifestations, to guide usage of drugs.
There are two types of illness:
1. Minor Illness or Neurosis
These are less serious and ability to comprehend reality is not lost. However, patient undergoes extreme sufferings. Among these most common are:
a) Anxiety Neurosis
Characterized by unpleasant emotions, associated with fear. There may be symptoms of sympathetic stimulation, particularly when in acute form and are produced when the person is exposed to new environment. If anxiety remains within limits, then it is normal/natural phenomenon. If it impairs the performance of the person, then it becomes pathological.
b) Hysterical Neurosis
In hysterical neurosis, symptoms are produced by autosuggestion. Patient suggests to himself that certain symptoms, illness is present in him. Then these symptoms actually appear in him e.g. blindness, paralysis can be produced by this.
There is genuine psychological problem though no organic problem.
c) Obsessional Neurosis
In this there is limited abnormality of thought and behavior. There are recurrent thoughts and ritual like behavior which person himself realizes that is abnormal, but cannot overcome, even with voluntary effort.
d) Phobic Neurosis
There is fear of unknown or of specific object, person or situation. E.g.
Claustrophobia –fear of closed spaces.
Agoraphobia –fear of open spaces
School phobias in children
e) Depressive Neurosis
Person is depressed. There is always underlying cause like death of dear or near one. This depressive neurosis differs from maniac depressive psychosis in magnitude. This is lesser in intensity.
Person is preoccupied with hi health. There are irrational ideas and person thinks he is suffering from illness although he is normal.
2. Major Illness or Psychosis
These are severe psychiatric problems with distorted thoughts, perceptions and behavior. They are broadly divided into:
Lesions in the brain can be identified. It is further divided into:
Syndrome characterized by hallucinations, excitement, restlessness, delusions and person may be disoriented. This may be drug induced.
There is degeneration of cortex, because of which cognitive and intellectual functions of a person are impaired.
Lesions in the brain cannot be identified. Further divided into:
I. Manic Depressive Psychosis
Serious emotional disorder in which there are cyclic attacks of mania and depression.
When patient is in maniac phase, there is elevation of mood, person talks a lot, walks a lot. There is reduced sleep and hyperactivity. Such patients can get aggressive and violent.
In depressive phase, there is sudden loss of interest, physical, mental slowing, ideas of guilt and self destruction.
Chronic progressive illness characterized by hallucinations, delusions and catatonia (abnormality of tone of muscles. There is hypertonia at rest, which gets normal during movement) and abnormality of thought process. Person thinks as if thoughts are inserted or recovered from brain by alien forces.
Incidence of schizophrenia is 1%.
Usually occurrence starts at less than 30 years of age.
Exact cause is not known.
However, it has very strong genetic basis. It runs in families
Can be due to viral infections, inside or outside the brain.
Due to developmental abnormality of limbic system
May be drug induced.
Dopamine hypothesis of Schizophrenia
It is said that schizophrenia is due to functional over activity of dopaminergic system in body. It may be due to:
- increased synthesis or release of dopamine
- Due to decreased metabolism of dopamine
- May be due to increased sensitivity of post-synaptic dopaminergic receptors.
Points in favor of dopamine hypothesis
- Most potent antipsychotics are D2 antagonists.
- Drugs that increase the levels of dopamine can produce psychosis like Ketamine, levo dopa and bromocryptine
- There are transient rise in levels of homovalenic acid i.e. metabolite of dopamine, in CSF, plasma and urine.
- In dead people on autopsy, dopamine density is raised, as determined by positron emission tomography.
Points against dopamine hypothesis
- Some antipsychotics are very potent drugs but not very effective D2 receptor blockers, implying role of other receptors.
- Now different receptors have been recognized. These are the cholinergic receptors, serotonin receptors, sigma (opioid) receptors; role of glutamate has been established.
Monoamine theory of psychiatric illness
According to this theory, monoamines play important role in psychiatric functions. Abnormality of these neurotransmitters can impair these functions. Drugs that alter levels of these neurotransmitters do produce important psychiatric illnesses. E.g.
- In mania, there is over activity of monoamines.
- In depression there is under activity of monoamines.
- In Schizophrenia, there is over activity of dopamine.
It is another subtype for antipsychotics. Drugs that decrease the motor activity and improve behavior of the patient. However they have little or no effect on spinal or unconditioned reflexes. It produces high incidence of extrapyramidal side effects at clinical effective dose.
There are five dopaminergic pathways:
- Mesolimbic/ Mesocortical pathways –concerned with behavior
Abnormality of mesolimbic pathway may produce hallucinations
Abnormality of mesolimbic pathway may produce social withdrawal and poverty of speech.
- Nigrostriatal pathway –concerned with coordination of voluntary movements
- Tuberoinfundibular pathway –concerned with endocrine effects
- Medullary periventricular pathway –eating behavior
- Incertohypothalamic pathway –animals studies indicate are concerned with populatory and behavior of animals
- D1———D1, D5 (Increase cAMP)
- D2———D2, D3, D4 (decrease cAMP)
D1 –located in putamen, olfactory tubercle, nucleus acubens
D5 –located in hippocampus and hypothalamus
D2 –located in putamen, olfactory tubercle, nucleus accubens, pre and post synaptically
D3 –located in frontal cortex, medulla and mid-brain