Question

current attempt in progress
although zoe only used ecstasy on a recreational basis, she wondered if it was starting to take its toll on her brain. she struggled with learning and memory more now than ever before. her friends also commented on how moody she was and worried about her sleep and appetite irregularities. what could account for these changes?
zoes sleep disturbances were caused by an increase in serotonin, and the remaining symptoms were attributed to sleep deprivation.
zoes dopamine level was increasing with every episode of ecstasy consumption thereby leading to the changes she was experiencing.
zoe was likely experiencing a reduction in serotonin from the drug use, which would explain these symptoms.
zoes symptoms must all be in her head as research has yet to link recreational use of ecstasy with any change in cognitive functioning.

Explanation:

Ecstasy use can deplete serotonin levels. Serotonin is involved in mood - regulation, sleep, appetite, and learning/memory. A reduction in serotonin can cause the symptoms Zoe is experiencing such as moodiness, sleep and appetite irregularities, and learning and memory struggles.

Answer:

Zoe was likely experiencing a reduction in serotonin from the drug use, which would explain these symptoms.