This narrative review exhibits the construction and validation of a hypothesis to explain how treatment non-adherence in people with chronic disease, a major issue in contemporary medicine, occurs. I propose that non-adherence to long-term therapies is at least in part due to failure to prioritize the future, which is caused by a condition I dub disruption in time projection. This article gives the rationale for this hypothesis, which is largely grounded on philosophical arguments. Then, it demonstrates the plausibility of the hypothesis: on the one hand, it is consistent with certain epidemiological data found in the literature. On the other, it is possible to predict the underlying mechanisms of this lack of prioritization from recent achievements of neuro-economics and neuroscience. Next, it reviews empirical data that provide an experimental verification for this explanatory hypothesis. Finally, a general evolutionary and philosophical meaning for adherence is proposed, considering the advantages of its preconditions, namely, patience and foresight.