Summary of Mental Disorders: An Introduction to Psychology and Neuroscience (2023)

15.1What are mental disorders?

Mental disorders are conditions characterized by abnormal thoughts, feelings, and behavior. While challenging, it is important that psychologists and mental health professionals agree on what types of inner experiences and behaviors represent the presence of a mental disorder. Inner experiences and behaviors that are atypical or go against social norms may indicate the presence of a disorder; however, each of these criteria alone is not sufficient. Pernicious dysfunction describes the view that mental disorders result from the inability of an internal mechanism to perform its natural function. Many of the features of the conceptualization of harmful dysfunction have been incorporated into the formal APA definition of mental disorders. According to this definition, the presence of a mental disorder is indicated by significant changes in thoughts, feelings, and behavior; These disorders must reflect some type of dysfunction (biological, psychological, or developmental), must significantly interfere with a person's life, and must not reflect culturally expected responses to specific life events.

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15.2Diagnosis and classification of mental disorders.

The diagnosis and classification of mental disorders are essential to the study and treatment of psychopathology. The classification system used by most American professionals is the DSM-5. The first edition of the DSM was published in 1952 and has been revised several times. The fifth and most recent edition, the DSM-5, was released in 2013. The diagnostic manual covers a total of 237 specific diagnosable diseases, each of which is described in detail, including its symptoms, prevalence, risk factors and comorbidities. Over time, the number of diagnosable conditions listed in the DSM has steadily increased, which has been criticized by some. However, the diagnostic criteria in the DSM are more explicit than in any other system, making the DSM system highly desirable for both clinical diagnosis and research.

15.3Perspectives on Mental Disorders

Psychopathology is very complex and encompasses a variety of etiological theories and perspectives. For centuries, mental disorders were viewed primarily from a supernatural perspective, and were believed to result from divine powers or from spirit possession. Some cultures continue to hold this supernatural belief. Today, many who study psychopathology look at mental illness from a biological perspective, in which mental disorders are largely the result of faulty biological processes. In fact, scientific advances over the past few decades have led to a better understanding of the genetic, neurological, hormonal, and biochemical basis of psychopathology. The psychological perspective, on the other hand, emphasizes the importance of psychological factors (e.g. stress and thoughts) and environmental factors in the development of mental disorders. A contemporary and promising approach is the consideration that the disorders arise from an integration of biological and psychosocial factors. The diathesis-stress model suggests that people with an underlying diathesis or susceptibility to a mental disorder are more likely than people without a diathesis to develop the disorder when confronted with stressful events.


Neurodevelopmental disorders are a group of disorders, typically diagnosed in childhood, characterized by personal, social, academic, and intellectual developmental deficits; These disorders include Attention Deficit/Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder. ADHD is characterized by a pervasive pattern of inattention and/or hyperactive and impulsive behavior that interferes with normal functioning. Genetic and neurobiological factors contribute to the development of ADHD, which can persist into adulthood and is often associated with poor long-term outcomes. Key features of autism spectrum disorder include deficits in social interaction and communication, and repetitive movements or interests. As with ADHD, genetic factors appear to play an important role in the development of autism spectrum disorder; Exposure to environmental pollutants such as mercury has also been linked to the development of this disorder. Although some believe that the MMR vaccine causes autism, the evidence does not support this claim.

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Schizophrenia is a severe disorder characterized by a complete breakdown in the ability to function in life; often requires hospitalization. People with schizophrenia experience hallucinations and delusions and have great difficulty regulating their emotions and behavior. Thinking is incoherent and disorganized, behavior is extremely bizarre, emotions are shallow, and motivation to participate in most basic life activities is lacking. Considerable evidence shows that genetic factors play a central role in schizophrenia; However, adoption studies have highlighted the additional importance of environmental factors. Brain and neurotransmitter abnormalities have also been linked, which may be related to environmental factors such as obstetric complications or exposure to influenza during pregnancy. A promising new area of ​​schizophrenia research is identifying people who experience prodromal symptoms and following them over time to determine what factors best predict the development of schizophrenia. Future research could allow us to identify those at particular risk of developing schizophrenia who might benefit from early intervention.

15.6mood swings

Mood disorders are those in which the person has severe mood and emotional disturbances. They include depressive disorders and bipolar and related disorders. Depressive disorders include major depressive disorders characterized by episodes of deep sadness and loss of interest or pleasure in usual activities and other associated features, and persistent depressive disorders characterized by a chronic state of sadness. Bipolar disorder is characterized by moods ranging from sad to elated; A diagnosis of bipolar disorder requires experiencing at least one manic episode, which is defined as a period of extreme elation, irritability, and increased activity. Mood disorders appear to have a genetic component, with genetic factors playing a greater role in bipolar disorder than in depression. Both biological and psychological factors play an important role in the development of depression.

15.7anxiety disorders

Anxiety disorders are a group of disorders in which a person experiences excessive, persistent, and distressing anxiety and fear that interferes with normal functioning. Anxiety disorders include specific phobias: a specific unreal fear; social anxiety disorder: extreme anxiety and avoidance of social situations; Panic Disorder: Suddenly panicked when there is no apparent reason to be afraid; Agoraphobia: intense fear and avoidance of situations from which it may be difficult to escape; and generalized anxiety disorder: a relatively continuous state of tension, apprehension, and fear.

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15.8Obsessive Compulsive Disorder and Related Disorders

Obsessive-compulsive and related disorders are a group of DSM-5 disorders that overlap somewhat in that each involves intrusive thoughts and/or repetitive behaviors. Perhaps the best-known of these disorders is obsessive-compulsive disorder, in which a person becomes obsessed with unwanted unpleasant thoughts and/or engages compulsively in repetitive behaviors or mental acts, perhaps to help cope with the obsessions. Body dysmorphic disorder is characterized by a person being overly preoccupied with one or more perceived flaws in their physical appearance that are absent or imperceptible to others. Preoccupation with perceived physical flaws causes the person to feel significant anxiety about their appearance to others. Hoarding disorder is characterized by persistent difficulty throwing or disposing of items, regardless of their actual value, often resulting in an accumulation of items that clutter and clutter your living space.

15.9Post-traumatic stress disorder

Post-Traumatic Stress Disorder (PTSD) was described for much of the 20th century as war shock and battle neurosis, with symptoms thought to result from the stress of active combat. Today, PTSD is defined as a disorder in which experiencing a deeply distressing or traumatic event, such as combat, sexual assault, or natural disaster, produces a constellation of symptoms that must last a month or more. These symptoms include intrusive and distressing memories of the event, flashbacks, avoidance of stimuli or situations related to the event, persistent negative emotional states, feelings of detachment from others, irritability, propensity for outbursts, and a tendency to be easily startled. Not everyone who experiences a traumatic event develops PTSD; A variety of risk factors related to its development have been identified.

15.10dissociative disorders

The hallmark of dissociative disorders is that people dissociate from their sense of self, leading to memory and identity disorders. Dissociative disorders listed in the DSM-5 include dissociative amnesia, depersonalization/derealization disorder, and dissociative identity disorder. A person with dissociative amnesia is unable to remember important personal information, usually after a stressful or traumatic experience.

Depersonalization/derealization disorder is characterized by recurrent episodes of depersonalization (ie withdrawal or unfamiliarity with oneself) and/or derealization (ie withdrawal or unfamiliarity with the world). A person with dissociative identity disorder exhibits two or more clearly defined and distinct personalities or identities, and lapses in memory for the time when another identity was present.

Dissociative identity disorder has generated controversy, mainly because some believe that if the portrayal of their symptoms benefits the patient in any way, either by avoiding negative consequences or taking responsibility for their actions, their symptoms can be faked by patients. Diagnosis rates for this disorder have increased dramatically following its portrayal in popular culture. However, many people legitimately suffer from this disorder throughout their lives.

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15.11personality disorder

People with personality disorders exhibit a personality style that is inflexible, causes stress and harm, and creates problems for themselves and others. The DSM-5 recognizes 10 personality disorders, which are divided into three groups. Cluster A disorders include those characterized by a bizarre and eccentric personality style. Cluster B includes personality disorders characterized primarily by an impulsive, dramatic, highly emotional, and unpredictable personality style, and Cluster C is characterized by a nervous and anxious personality style. Two cluster B personality disorders, borderline personality disorder and antisocial personality disorder, are particularly problematic. People with borderline personality disorder have marked instability in mood, behavior, and self-image, as well as impulsiveness. They cannot bear to be alone, are unpredictable, have a history of stormy relationships, and often display intense and inappropriate anger. Genetic factors and adverse childhood experiences (eg, sexual abuse) appear to be important in their development. People with antisocial personalities show a lack of respect for the rights of others; they are impulsive, deceitful, irresponsible and have no guilt. Genetic and socialization factors appear to be important in the development of antisocial personality disorder. Research has also shown that people with this disorder don't experience emotions in the same way as most people.

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1. Trauma and the Nervous System: A Polyvagal Perspective
(The Trauma Foundation)
2. Applied Neuroscience vs Psychology and Neuroscience of Mental Health MSc - What’s the Difference?
3. An Overview of Neuropsychiatry
(The Encephalitis Society)
4. The Future of Mental Health Treatments and Neuroscience
(BRAIN Initiative ®)
5. Neurobiology of Mental Illness
(Farid Youssef)
6. Intro Psych: 13.1 Psychological Disorders Overview
(Dr. Kristin Atchison)
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