Interventionism and Intelligibility: Why Depression Is Not (Always) a Brain Disease

Area of Science:

• Philosophy of Medicine
• Psychiatry
• Neuroscience

Background:

• Major Depressive Disorder (MDD) carries a significant global health burden.
• The assertion that MDD is a "brain disease" is common but requires precise interpretation.
• Understanding the causal mechanisms of MDD is crucial for effective treatment and classification.

Purpose of the Study:

• To critically evaluate the "brain disease" conception of MDD.
• To examine the causal relationship between external factors and MDD symptoms.
• To propose a revised nosological framework for depression.

Main Methods:

• Conceptual analysis of the "brain disease" hypothesis for MDD.
• Review of empirical evidence on the causes of depression.
• Philosophical argumentation regarding causation in disease.

Main Results:

• The "brain disease" model of MDD implies "brute" causation by brain dysfunction, which is often inaccurate.
• Empirical evidence supports psychological factors and adverse life events as significant causes of MDD symptoms.
• The "brain disease" conception incorrectly excludes content-sensitive causation from environmental factors.

Conclusions:

• MDD causation is often content-sensitive, linking adverse conditions to symptoms, rather than solely "brute" brain dysfunction.
• The "brain disease" model is an oversimplification that overlooks crucial psychological and environmental influences.
• Reinstating the distinction between endogenous and exogenous depression is supported by the evidence of diverse causal pathways in MDD.