Schizotypal autism or Mendelsohnn's syndrome is an extraordinarily rare neurodevelopmental disorder similar to Asperger syndrome; however, it originates from a schizotypal continuum rather than an autistic spectrum. It is characterized by impaired social interaction, non-verbal communication, ritualistic and obsessive behaviour, an above average intelligence and schizotypal symptoms often resulting in secondary depression and anxiety. It is a lifelong condition; however, it becomes particularly notable in periods of stress. It occurs in North Eastern European populations, and is only officially recognised in Russia, Finland, Kyrgyzstan, Estonia and Belarus as a psychiatric disorder. It more than likely exists in other locations but is not recognised as a disorder, thus cannot be officially diagnosed.

A classical symptom is seasonal affective disorder. For a diagnosis, patients need specific symptoms associated with "classical" Asperger's syndrome. These are usually present from toddler age, like an ASD:

Patients also need symptoms of schizotypy, ^[1] which usually become more prominent in late childhood years:

In late childhood patients typically start to require medical intervention because of suicidal thoughts.

Due to the wide range and severity of symptoms therapeutic methods often seem to fail; however, CBT is usually used.

The following medications may be beneficial for individual symptoms:

It is currently understood that around 1000 people have this condition.

Due to this condition only being recognized in certain countries, the statistics may be inaccurate.

It is estimated that over 80% of cases are in Finland and North West Russia.

The vast majority of literature on schizotypal autism is in Finnish or Russian.

Vacilly Mendelsohnn noted that due to the extremely high IQ of patients he could guarantee that the world's most intelligent person has this condition and speculates that mathematician Grigori Perelman does.