Which long-term effect could be associated with high consumption of marijuana?

High consumption of marijuana is associated with adverse effects on cognition, making this the correct answer. Long-term marijuana use can lead to issues such as impaired memory, attention deficits, and difficulties with problem-solving. These cognitive impairments can affect various aspects of daily functioning, including academic and occupational performance, and can last beyond the period of intoxication. Research indicates that particularly in adolescent users, the developing brain may be more susceptible to these cognitive effects, leading to lasting changes in brain function.

On the other hand, decreased appetite is typically associated with marijuana use in the short term rather than long-term effects. Improved cognitive function contradicts the existing evidence surrounding marijuana's impact on the brain, as numerous studies have indicated a decline rather than an enhancement in cognitive abilities. Heightened motivation is often misconceived; chronic marijuana use can actually lead to a lack of motivation, commonly referred to as "amotivational syndrome," where individuals may become apathetic or disengaged from their usual interests and activities.