I dont see any in pubmed either. I guess people wil have to decide for themselves.
Firstly for clarity niacin is just the cheap regular, vitamin B3 (the flushing kind!).
Here's a great link on the subject that's well worth the read. Dr Hoffer treated these patients throughout his career and his legacy continues ("orthomolecular medicine").
Niacin Treatment of Schizophrenia
Here are some interesting articles on the subject below.
3. Hoffer AF, Osmond H, Smythies, Schizophrenia: a New Approach. II. Results of a Year's Research. J. Mental Sci. 100: 29-45, 1954.
Schizophrenia; a new approach. II. Result of a year's research. - PubMed - NCBI
4. Hoffer A, Osmond H. Treatment of schizophrenia with nicotinic acid: a ten-year follow-up. Acta Psychiat Scand 1964, 40: 171-189.
TREATMENT OF SCHIZOPHRENIA WITH NICOTINIC ACID. A TEN YEAR FOLLOW-UP. - PubMed - NCBI
5. Niacin and Schizophrenia: History and Opportunity.
Niacin and Schizophrenia: History and Opportunity
6. To Give Credit Where Credit is Due.
To Give Credit Where Credit is Due
7. Abram Hoffer Centenary.
http://orthomolecular.org/resources/omns/v13n19.shtml