Familial risk, shared familial risk and partner-associated risk of neurodegenerative and psychiatric diseases

Abstract Brain diseases cluster within families, but the extent of familial risk across different brain diseases remains unclear. In this study, 10,620 participants reported 7 neurodegenerative and 9 psychiatric diseases in 53,361 family members. Familial risk was assessed by determining if a first-degree relative affected by a brain disease increased the risk of the proband having the same disease. Shared familial risk referred to increased risk of the proband having a different brain disease. Similarly, we assessed (shared) partner-associated risk using partner data. Familial risk was present across all neurodegenerative and psychiatric diseases studied. Shared familial risk was present between some neurodegenerative diseases, while prominent between all psychiatric diseases. Four associations were identified between neurodegenerative and psychiatric diseases. (Shared) partner-associated risk was almost exclusively seen in psychiatric diseases. Overall, neurodegenerative diseases exhibited distinct familial patterns, while psychiatric diseases shared a continuum of familial and partner-associated susceptibility.