Positive symptoms of schizophrenia, specifically hallucinations and delusions, are thought to be caused by hyperactivity of which neurotransmitter?

Dopamine.

Explanation:

Schizophrenia is a mental illness characterized by psychotic episodes and the inability to relate thoughts, feelings and actions, accompanied by delusions, hallucinations (auditory, visual, olfactory and tactile), incoherent thoughts, memory disorders and, in occasions, confusion. Dopamine is a hormone synthesized by the brain that acts as a neurotransmitter and allows the connection between neurons. Studies suggest that some of these alterations in mental functions are caused by an excess in the activity of dopaminergic synapses, that is, there is a hyperactivity in those connections where dopamine is produced and expelled, which range from the ventral tegmental area to the nucleus accumbens and the amygdala, which are the main ones responsible for synthesizing and expelling dopamine from brain reward systems.

an individual’s sex (i.e., whether they are a male or female) is determined by the sex chromosomes. most people have two sex chromosomes, one that is inherited from their mother and one that is inherited from their father. typically, females have two x chromosomes (xx) and males have one x chromosome and one y chromosome (xy). conditions caused by changes (“mutations”) in genes located on the x chromosome are considered x-linked.

x-linked recessive inheritance

most x-linked conditions are recessive. this means that in a person with two x chromosomes (most females), both copies of a gene (i.e., one on each x chromosome) must have a change or mutation whereas in a person with one x chromosome (most males), only one copy of a gene must have a mutation. a female with a mutation in one copy of a gene on the x chromosome is said to be a “carrier” for an x-linked condition. a male with a mutation in a gene on the x chromosome is typically affected with the condition. because females have two copies of the x chromosome and males have only one x chromosome, x-linked recessive diseases are more common among males than females. however, x-linked recessive diseases can occur in both males and females.

for x-linked recessive disorders, an unaffected carrier mother who has a mutation in a gene on the x chromosome can transmit either the x chromosome with this mutation or a “normal” x chromosome to her children. if the father is unaffected, none of her daughters will be affected and all of her daughters will be unaffected—since they will inherit at least one normal x chromosome from their father. however, each daughter will have a 50% chance of being an unaffected carrier like her mother and a 50% chance of both x chromosomes being normal.

the correct answer is sex-linked recessive.

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