Physical factors
The development of paranoia and hallucinations in old age have been related to both auditory and visual impairment, and individuals with paraphrenia often present with one or both of these impairments. Hearing loss in paraphrenics is associated with early age of onset, long duration, and profound auditory loss. History
The term paraphrenia was originally popularized by Karl Ludwig Kahlbaum in 1863 to describe the tendency of certain psychiatric disorders to occur during certain  transitional periods in life (describing paraphrenia hebetica as the insanity of the adolescence and paraphrenia senilis as the insanity of the elders.The term was also used by Sigmund Freud for a short time starting in 1911 as an alternative to the terms schizophrenia and dementia praecox, which in his estimation did not correctly identify the underlying condition, and by Emil Kraepelin in 1912/3, who changed its meaning to describe paraphrenia as it is understood today, as a small group of individuals that have many of the symptoms of schizophrenia with a lack of deterioration and thought disorder. Kraepelins study was discredited by Wilhelm Mayer in 1921 when he conducted a follow-up study using Kraepelins data. His study suggested that there was little to no discrimination between schizophrenia and paraphrenia; given enough time, patients presenting with paraphrenia will merge into the schizophrenic pool. However, Meyers data are open to various interpretations. In 1952, Roth and Morrissey conducted a large study in which they surveyed the mental hospital admissions of older patients.
Approximately 4% of Patau syndrome with unknown outcomes are likely to result in a live birth, therefore the total number of live births is estimated to be 18. References
External links

Trisomy 13 at WebMD