Evidence for a possibly X-linked trait related to affective illness

Area of Science:

• Psychiatry
• Genetics
• Longevity Studies

Background:

• Previous research suggested a link between maternal grandfather longevity (MGFL) and affective illness in grandsons.
• This association had not been previously replicated, necessitating further investigation.

Purpose of the Study:

• To replicate the negative association between MGFL and affective illness in grandsons.
• To investigate the potential recessive and X-linked nature of this association by examining MGFL in relation to maternal affective illness.
• To explore the predictive value of MGFL for affective illness by assessing the association between probands' affective illness and their mortality.

Main Methods:

• A 60-year prospective study of men, initiated in 1940, provided data on depressive illness in relatives and ancestral longevity.
• Affective illness in probands was assessed using categorical, dimensional, and operational methods, including the Lazare Personality Inventory, to ensure diagnostic certainty.

Main Results:

• A significant negative association was found between MGFL and affective illness in brothers (p = 0.003).
• Maternal affective illness showed no association with MGFL.
• Emotional lability in probands was negatively associated with MGFL, and lower affective distress correlated with significantly reduced mortality.
• Conversely, higher affective distress was linked to increased mortality.

Conclusions:

• The findings suggest a potential role for a recessive X-linked gene(s) in depressive illness.
• The strong association between proband affective distress, mental health, and MGFL, alongside the lack of association with maternal factors, supports this genetic hypothesis.