Schizophrenia spectrum disorders: Pathology review

A 32 year old male named Bert is brought to the psychiatric clinic by his concerned mother, who thinks that Bert’s behavior has changed over the past 9 months. Upon further questioning, Bert’s mother reveals that he has been isolating himself, and stopped calling or visiting his family and friends. Bert says that he must stay at home because some aliens have been trying to control his mind. On physical examination, Bert appears disheveled, has poor eye contact with others, and shows little facial expression. You decide to order a toxicology screen, which comes back negative.

Some days later, you see a 25 year old female named Akuchi, who comes in for a psychiatric consultation. The first thing you notice is that she’s wearing a long coat and a sweater with a mini skirt and flips flops. Akuchi mentions that she has always had trouble fitting in and does not have any friends, even though she’d really like to. When you ask what she does during her free time, Akuchi tells you that she spends most of her time in her room, since she’s convinced that there are vampires hiding in her house, although she’s never seen or heard one. On physical examination, Akuchi’s speech seems peculiar, since she creates new versions of words and often doesn’t make sense.

Okay, based on the initial presentation, both Bert and Akuchi seem to have some form of schizophrenia spectrum disorder. These are a group of conditions, including schizophrenia, that are characterized by difficulty thinking clearly, making good decisions, distinguishing reality from imagination, and behaving appropriately, sometimes even to the point where they interfere with day-to-day activities like working, studying, eating, and sleeping. Now, the main risk factors for developing a schizophrenia spectrum disorder seem to include having a family history, experiencing a personal trauma, or heavy use of substances, and especially cannabis, during adolescence. And that’s actually high yield!

However, the underlying cause is poorly understood; for your exams, what you need to remember is that it’s related to altered levels of the neurotransmitter dopamine that affect two out of the four dopamine pathways in the brain: the mesocortical pathway, which helps regulate emotions, and the mesolimbic pathway, which controls motivation and desire. Bear in mind that these disorders don’t affect the two other dopamine pathways, meaning the nigrostriatal pathway, which contains motor neurons that bypass the medullary pyramids, to control involuntary movements and coordination; and the tuberoinfundibular pathway, which releases dopamine to limit the secretion of prolactin.