Psychological Disorders Chapter. Psychological Disorders An Introduction.
Neurochemical Basis of Psychological Disorders
Transcript of Neurochemical Basis of Psychological Disorders
Neurochemical Basis of Psychological
Disorders
Naditha AmarakoonUndergraduate University of Colombo
Final Year 1 Credit Report (Received A+)
Neurochemicals An organic molecule that participates in
neural activity. Often refers to neurotransmitters and other
molecules like neuro-active drugs that influence neuron function.
Eg. o Serotonino Dopamine o Nerve growth factor
Psychological Disorders
Diagnosis based on the Diagnostic and Statistical Manual of Mental Disorders, or DSM published by the American Psychiatric Association (APA)
DSM-IV published in 1994, ("text revision" in 2000) is presently used.
Dissociative disorders Mood disorders Anxiety disorders Psychotic disorders Eating disorders Personality disorders Many other categories.
Cause of Psychological Disorders
Causes of disorders are complex, and interact and vary according to the particular disorder and individual.
Genetics, early development, drugs, disease or injury, neurocognitive and psychological mechanisms, and life experiences, society and culture can all contribute to the development or progression of different mental disorders.
Biological Psychiatry
Biological psychiatry, or biopsychiatry is an approach to psychiatry that aims to understand mental disorder in terms of the biological function of the nervous system.
History
Sigmund Freud's mentor, Prof. Ernst Wilhelm von Brücke, strongly believed that thought and behavior were determined by purely biological factors.
Freud initially accepted this and was convinced that certain drugs (particularly cocaine) functioned as antidepressants.
Nearly 100 years ago, Prof. Harvey Cushing, noted that pituitary gland problems often cause mental health disorders.
Catecholamine Hypothesis of Affective Disorders
Published in 1965 by Joseph Schildkraut associated low levels of neurotransmitters with depression.
This conceptual framework has been challenged, though no alternative demonstrably superior hypothesis has emerged.
Today
Increasing evidence points to various mental health disorders as a neurophysiological problem which inhibits neuronal plasticity.
Some examples for the neurochemical basis of Psychological Disorders
Schizophrenia
Psychiatric diagnosed condition that describes a mental disorder characterized by abnormalities in the perception or expression of reality.
Manifests commonly as auditory hallucinations, paranoid or bizarre delusions or disorganized speech and thinking in the context of significant social or occupational dysfunction.
Attention-Deficit Hyperactivity Disorder (ADHD)
A neurobehavioral developmental disorder affecting about 3-5% of the world's population and typically presents in children.
Characterized by a persistent pattern of inattention and/or hyperactivity, as well as forgetfulness, poor impulse control and distractibility.
Deficits in dopamine levels are implicated in (ADHD).
Stimulant medications used to successfully treat the disorder increase dopamine neurotransmitter levels, leading to decreased symptoms.
Neurogenic hypothesis of depression Explains pharmacological antidepressant action,
including the time lag from taking the drug to therapeutic onset, why down regulation (not just up regulation) of neurotransmitters can help depression, why stress often precipitates mood disorders, and why selective modulation of different neurotransmitters can help depression.
May also explain the neurobiological mechanism of other non-drug effects on mood, including exercise, diet and metabolism.
Role of gamma-aminobutyric acid in Anxiety
Electrophysiological analysis revealed that benzodiazepines selectively enhance gamma-aminobutyric acid (GABA) neurotransmission and the presence of a specific population of benzodiazepine binding sites on neuronal membranes.
Coupled with findings that barbiturates may act, at least in part, by interacting with the GABA receptor-coupled chloride channel, suggest that pharmacological manipulations of the GABA system can alleviate the symptoms of anxiety.
The anxioselectivity of the benzodiazepines may be related to the fact that they activate only a certain population of GABA receptors, whereas barbiturates can potentiate the majority of these sites.
These discoveries point to the possibility that alterations in the GABA system may partially explain the neurochemical basis of anxiety.
Panic Attack \ DisorderFrequency and intensity of PA varies during menstrual cycle and
pregnancy Evidence exists that gonad hormones have a strong influence on PD,
especially in terms of frequency and intensity of PA. Spontaneous panic attacks rarely start before puberty or after
menopause, suggesting that, in women, occurrence of PA may be linked to production of female reproductive hormones.
Premenstrual exacerbation of panic symptoms has been documented, while women with LLPDD are more sensitive to panic-provocation procedures.
In addition, panic rate in women with or without LLPDD increases when they are challenged during the luteal phase, the LLPDD patients having a higher rate.
This is attributed to a drop in progesterone levels before the onset of menses, the women with largest progesterone fluctuation being most vulnerable. Clinically, a marked decrease of panic has been observed during pregnancy and lactation, with postlactational exacerbation of symptoms. These changes most likely reflect increased levels of progesterone, estrogen and oxytocin during pregnancy or lactation. The fact that the condition of PD patients improves during this time is a strong argument for the biological view of PD.
Criticism
Some dispute biological psychiatry as a scientific concept or as having a proper empirical basis, for example arguing that there are no known biomarkers for recognized psychiatric conditions.
Alternative theories and models view mental disorder as non-biomedical and may explain it in terms of emotional reactions to negative life circumstances or to acute trauma.
Fields such as social psychiatry, clinical psychology, and sociology may offer non-biomedical accounts of mental distress and disorder for certain aliments and are sometimes critical of biopsychiatry.
Social critics believe biopsychiatry fails to satisfy the scientific method because they believe there is no testable biological evidence of mental disorders.
Acknowledgements
Www.wikipedia.com Www.reference.com American Psychiatric Association U.S. National Library of Medicine U.S. National Institutes of Health Thomas Higher Education Publications
Thank You!