Higher g promotes more learning, and it increases exposure to learning opportunities. So, the problem is not in the lack of access to health-care, but the patient's failure to use it effectively when delivered. Low literacy has been associated with low use of preventive care, poor comprehension of one's illness – even when care is free. Health self-management is important because literacy provides the ability to acquire new information and complete complex tasks and that limited problem solving abilities make low-literacy patients less likely to change their behaviour on the basis of new information. Chronic lack of good judgement and effective reasoning leads to chronically poor self-management. There have been many reasons posited for the links between health and intelligence. Although some have argued that the direction is one in which health has an influence on intelligence, most have focused on the influence of intelligence on health. Although health may definitely affect intelligence, most of the cognitive epidemiological studies have looked at intelligence in childhood when ill health is far less frequent and a more unlikely cause of poor intelligence. Thus most explanations have focused on the effects intelligence has on health through its influence on mediating causes. Various explanations for these findings have been proposed:  "First, ...intelligence is associated with more education, and thereafter with more professional occupations that might place the person in healthier environments. ... Second, people with higher intelligence might engage in more healthy behaviours. ... Third, mental test scores from early life might act as a record of insults to the brain that have occurred before that date. ... Fourth, mental test scores obtained in youth might be an indicator of a well-put-together system. It is hypothesized that a well-wired body is more able to respond effectively to environmental insults..." The System integrity hypothesis posits that childhood intelligence is just one aspect of a well wired and well-functioning body and suggests that there is a latent trait that encompasses intelligence, health and many other factors. This trait indexes how well the body is functioning and how well the body can respond to change and return to a normal balance again (allostatic load). According to the system integrity hypothesis lower IQ does not cause mortality but instead poor system integrity causes lower intelligence and poorer health as well as a range of other traits which can be thought of as markers of system integrity. Professor Ian Deary has proposed that fluctuating asymmetry, speed of information processing, physical co-ordination, physical strength, metabolic syndrome and genetic correlation may be further potential markers of system integrity which by definition should explain a large part of or nullify the relationship between intelligence and mortality.