The focus of our research is on whether common psychiatric and neurodegenerative disorders share pathogenesis while having similar epidemiological risks. We discover eight significant genetic associations between psychiatric and neurodegenerative disorders using 25 GWAS results and LD score regression. To identify cis- and trans-transcripts and proteins that are compatible with a pleiotropic or causal function in each disease, we combine the GWAS data with human brain transcriptomes (n=888) and proteomes (n=722); these proteins are referred to as causal proteins for brevity. We discover a wide variety of unique and common causative proteins within each illness group. Surprisingly, psychiatric illnesses and neurodegenerative diseases share 30% of the causative proteins. Furthermore, compared to what would be expected by chance, we discover 2.6 times more protein-protein interactions among the psychiatric and neurodegenerative causative proteins. Our findings collectively imply that many psychiatric and neurodegenerative disorders share genetic and molecular pathogenesis, which has significant implications for early diagnosis and the development of therapeutics.
