Is there a familial overlap between dementia and other psychiatric disorders?

Background: Cognitive and psychiatric features are important components of dementia. Early onset dementia (EOD) has been found to be associated with a greater genetic basis. If this is the case, EOD could have genetic association with psychiatric illnesses, given the presence of more behavioral disturbances in this condition. There is a definite need to explore the presence of psychiatric symptoms and disorders in families of patients with dementia. Methods: The authors compared 52 proband families of dementia and 45 control families in order to assess the familial co-aggregation of major psychiatric illnesses. The cumulative risk in first degree relatives in the two groups for major psychiatric illnesses was calculated using Kaplan Meier Survival analysis. Early onset and late onset dementia proband families were compared separately with control families for the same. Results: There was a significantly higher morbid risk for psychosis in dementia proband families (generalized Wilcoxon, Breslow -4.165, p = 0.041). Also, the morbid risk was higher in early onset dementia proband families (generalized Wilcoxon, Breslow -6.16, p = 0.013) while it was not so in late onset dementia proband families (generalized Wilcoxon, Breslow -2.99, p = 0.084) Conclusion: There is a possible genetic overlap between dementia and psychosis. This appears to be more pronounced with early onset dementia than with late onset dementia.