GN 301 Module 7: Mental Health Disorders

Compare/Contrast mental health disorders and intellectual disabilities:

Mental Stability v Mental Ability

Rate of occurrence of mental health disorders in population

* 3% of population have intellectual disabilities
* 1 in 10 people hospitalized for a mental health disorder
* Half of hospital beds in United States filled with patients with a mental health disorder

Purpose of Nerve Cells

The neurons are the cells that we think of when we think of transmission of information and impulses from remote areas of our body to our brain. Neurons communicate across spaces called synapses using neurotransmitters.

Purpose of Neuroglia Cells

1 trillion neuroglia cells. The neuroglia cells guide development and movement of the neurons in the developing embryo. They produce growth factors throughout your life and they can divide.

Neural transmission

* Across spaces called synapses

Gene action sites for neurotransmission

1. Production of the myelin sheath
2. Synthesis of neurotransmitter
3. Transporter protein in sending cell
4. Receptor protein in receiving cell

**Parkinson’s Disease**

Individuals with Parkinson’s Disease have a clear mind but gradually lose control over muscles.

One characteristic symptom is a resting tremor or shakiness. Muscles tend to be more rigid than normal. Another early symptom is shaky and smaller handwriting.

Individuals with Parkinson’s cannot properly metabolize dopamine. Several genes have been implicated – with both dominant and recessive forms correlated with the disorder. Environmental factors are also thought to be important – particularly since most cases are found in families without a family history of the disorder.

The average age at onset of Parkinson’s is 62, but diagnosis does not always occur when symptoms first present. The medication L-dopa is often prescribed to help relieve symptoms. Probably the most famous person with this disorder is the actor, Michael J. Fox.

He was diagnosed in 1991 but kept the knowledge private until 1999. Since that time, he has been a vocal spokesperson for Parkinson’s and active in raising funds for research on the disorder.

Autism Spectrum

Individuals with autism are characterized by difficulties with social interaction and the ability to communicate. Some have a tendency to engage in repetitive behaviors.

Phenotypes for individuals with autism range from nonverbal to high functioning.

Asperger syndrome is one of the milder forms of autism. While these individuals face challenges and are often are uncomfortable with new situations and like repetition and schedule, they can be high functioning, with many completing college and having productive careers. In all cases, early diagnosis is important so that appropriate intervention and therapies can be used to help affected individuals maximize their abilities.

The region of chromosome #7 which contains genes important for speech and language development has been implicated in many cases. The gene for the transport of serotonin on chromosome #17 and the oxytocin receptor gene on chromosome #3 have also been implicated.

Sleep Disorders

Individuals with narcolepsy can suddenly fall into a short, but deep sleep.

A similar phenotype was seen in Dobermans. Breeding lines with the mutation were established to study the disorder, and a mutation in a gene for a receptor on brain cells was implicated in the Doberman population. This population has led to findings of similar genes in human.

Animal models have been an integral part of research for complex genetic disorders.

Alzheimer’s Disease

Alzheimer’s disease was named for Alois Alzheimer who first diagnosed the disorder in 1906. We tend to think of Alzheimer’s as an “old age” disorder

Today, we recognize that Alzheimer’s patients suffer from a progressive loss of memory, motor activity and the ability to recognize even the closest relatives and loved ones, and as body systems can no longer function, eventual death.

It is the 6th leading cause of death in the US. It typically affects individuals over 60 with the risk doubling every 5 years after age 65.

Persons with at least one first-degree relative are 3.5 times more likely to develop Alzheimer’s disease

Amyloid Plaques

* made of beta-amyloid protein
* Protein is “sticky”
* Blocks neural communication at synapses
* Activates immune cells causing inflammation and destruction of the disabled cells

Neurofibrillary Tangles

* Destroy cellular transport system for food, cellular components, etc.
* Twisted strands of Tau proteins block system

Alleles for abnormal production of and regulation of the Beta Amyloid protein and the Tau protein have been implicated in ________

Alzheimer’s Disease

**Apoliprotein E allele ε4 (APOE-ε4)**

* Increases likelihood of developing disease
* Does not guarantee disease
* Located on Chromosome 19
* Implicated in 50% of late onset cases
* May make symptoms appear at younger age
* Involved in cholesterol metabolism, transport and storage

General Addiction

is a compulsive physiological and psychological need for a habit forming substance.

Alcoholism:

addiction to alcohol; an important role of genetics in alcoholism (how well the body detoxifies alcohol, how well individual handles craving feelings). Abuse of alcohol can cause degeneration of brain and nerve cells, Alcoholics are often placed in hospitals for their addiction and to help them safely withdraw from over-use of alcohol.

Eating Disorders:

anorexia nervosa, bulimia nervosa, binge eating

* Levels of serotonin related to eating disorders
* Low serotonin leads to depression
* Binge eating increases serotonin level and leads to feeling of well-being
* High serotonin leads to feelings of anxiety
* Starving self lowers serotonin to give a calming effect

**Genetic Influences** of eating disorders

* People with eating disorders are 2X as likely to have variations in gene for serotonin reception
* Genes on chromosomes 1 and 14 are correlated with increased risk of developing eating disorders

Schizophrenia

10% genes shared with various relatives

Individuals with schizophrenia have an altered perception of reality. They often have difficulty organizing thoughts and speech and can suffer delusions and hallucinations. They often do not express emotion as readily. This can lead to social isolation, which in turn can lead to intellectual deterioration. Many schizophrenics report hearing voices that tell them to do destructive things.

Schizophrenia is under the control of many genes and is also affected by the environment.

Schizophrenia is estimated to account for a large portion of mental disorders. Symptoms often begin in early adulthood (18 - 33 years).

Bipolar Disorder

* More than 1 type
* X-linked dominant
* Autosomal genetic control
* MZ:DZ = 77:19
* 40% of first degree relatives (parents, sibs, children) also affected
* Rapid mood changes
* Alternating behavior patterns
* Sometimes introverted – Sometimes outbursts
* Ranging from severe depression to state of euphoria

Bi-polar disorder used to be called manic depression.

* There is a strong genetic component to this disorder although the environment clearly can also influence phenotype as identical twins do not always share this phenotype. It has been noted that 40% of first degree relatives, which include parents, siblings and children of an affected individual, are also affected
* Bi-polar disorder is characterized by behavior patterns that span a broad range. Individuals may sometime act very introverted and other times may have loud outbursts. Individuals have a range of emotions with extremes such as severe depression, feelings of hopelessness and suicidal thoughts. On the other side of the spectrum, individuals may have strong feelings of euphoria and well-being.