They concluded that the environment influenced the development of children and that this was especially important for the development of social competence. According to them, infants needed to be in contact with their mothers to receive sufficient love and care for their development. In the 1940s, the idea that infections led to hospitalism was increasingly criticized, especially since hospitalized infants were often kept alone in small cubicles, without any contact with caregivers or external stimuli, to prevent cross-infections.In 1945, the psychoanalyst René Spitz redefined the term hospitalism by arguing that the mortality rate of infants was still high, despite the isolation in cubicles, because the lack of maternal care impaired their development. Spitz conducted research for his hypothesis by comparing infants in a foundling hospital in Mexico and in a prison nursery in New York with two control groups of children growing up with their families. With the help of Katherine Wolf, he assessed the development of the infants using the Viennese Baby Tests. Spitz concluded that the decline in development and the high susceptibility to diseases he discovered in institutionalized babies were not due to a lack of environmental stimuli, since the prison nursery infants actually had access to toys, but mostly due to emotional and social deprivation. According to Spitz, a stable and intimate mother-child relationship is critical for the healthy development of the child. In his short film, Grief: A Peril in Infancy, he demonstrated the consequences of hospitalism.
Symptoms are largely observable in behaviour, but a patients psychological or physical impairments are largely driven by the cause of their condition, and as such not all patients experience the same suite of problems. Physical impairments include physical underdevelopment, reduced motor speed, and increased risk of rapid-onset muscle atrophy. Patients commonly suffer from maladaptive or disruptive eating behaviour, which results in a general decrease in stamina. This has been linked to malnutrition, extreme weight loss, and food addiction. Patients tend to have a strong predisposition to marasmus, which increases mental and physical fragility, alongside an impairment of their immune system, leading them to be at higher risk for infections and viral diseases. Infants also experience a higher mortality rate. The psychological circumstances fit this image. Especially in children that stayed in orphanages for a long time and suffer from deprivation syndrome – the sensory withdrawal before adulthood resulting in physical and psychological damages – one can observe a reduction of activities due to a lack of motivation and suppression of feelings. Sleeplessness, loss of weight and apathy are additional symptoms of depression that can also play a role. Another effect of withdrawal of sensory desires in an early age are personality disorders as for example borderline and attachment and adjustment disorders that are especially seen in behavioral abnormalities.These abnormalities can consist of stereotypes – a motor restlessness that results in showing repetitive and consistent motor processes and spoken utterances that do not have any goal or function and occur in absolutely unfitting situations.