Evidence for their role includes lesions found in autopsies. CSF samples from KLS patients indicate that the condition has a different cause than influenza-associated encephalopathy. Triggers of KLS may also affect the blood-brain barrier, which could play a role in the condition. There is limited evidence of what role hypocretin may play, although it often influences hypersomnia.Androgen might (indirectly) block melatonin receptors, possibly by means of vasodilation, and cause cholinergic abnormalities in some cases of Kleine–Levin syndrome.Because KLS occurs at a much higher rate in Jews and in some families, it is likely that there is some genetic component in addition to environmental factors. Genetic studies hold promise for understanding the disease, but they have yielded inconsistent results and few patients are available for testing.Epilepsy and depression do not appear to cause KLS. The conditions rapid onset after infections indicates that the immune system is not to blame.One study has suggested a link to the gene LMOD3 on chromosome 3. Diagnosis
KLS can be diagnosed when there is confusion, apathy, or derealization in addition to frequent bouts of extreme tiredness and prolonged sleep. The earliest it can be diagnosed is the second episode, this is not common. The condition is generally treated as a diagnosis of exclusion. Because KLS is rare, other conditions with similar symptoms are usually considered first.MRIs can determine if the symptoms are caused by certain brain disorders, stroke, and multiple sclerosis. Lumbar puncture can determine if encephalitis is the cause. KLS must be differentiated from substance abuse by toxicology tests.
Future research should focus on genetic and environmental risk factors to home in on specific brain regions and neurotransmitters that may be implicated in social anhedonias cause and could be targeted with medication or behavioral treatments. Social support may also play a valuable role in the treatment of social anhedonia. Blanchard et al. found that a greater number of social supports, as well as a greater perceived social support network, were related to fewer schizophrenia-spectrum symptoms and to better general functioning within the social anhedonia group. So far, no medicine has been developed to specifically target anhedonia. Gender differences
In the general population, males score higher than females on measures of social anhedonia. This sex difference is stable throughout time (from adolescence into adulthood) and is also seen in people with schizophrenia-spectrum disorders. These results may reflect a more broad pattern of interpersonal and social deficits seen in schizophrenia-spectrum disorders. On average, males with schizophrenia are diagnosed at a younger age, have more severe symptoms, worse treatment prognosis, and a decrease in overall quality of life compared to females with the disorder. These results, coupled with the sex difference seen in social anhedonia, outline the necessity for research on genetic and hormonal characteristics that differ between males and females, and that may increase risk or resilience for mental illnesses such as schizophrenia.