How Do Depression and Personality Disorders Differ in Symptoms and Cognitive Function?

What you need to know

• People with personality disorders tend to report more severe depressive symptoms than those with major depression alone, even when clinician ratings show the opposite.
• Both groups show improvements in mood and cognitive function during inpatient treatment, but those with personality disorders continue to report greater subjective cognitive difficulties.
• Understanding these differences in subjective versus objective symptoms can help guide diagnosis and treatment approaches for depression and personality disorders.

Understanding Depression and Personality Disorders

Depression and personality disorders are two distinct but often overlapping mental health conditions. Major depressive disorder (MDD) is characterized by persistent feelings of sadness, hopelessness, and loss of interest in activities. Personality disorders involve long-standing patterns of behavior and inner experience that deviate from cultural norms and cause distress or impairment.

While these conditions can occur separately, they also frequently co-exist. This overlap can make accurate diagnosis and treatment challenging, especially in inpatient settings where clinicians must make quick decisions about care. To shed light on this complex relationship, researchers conducted a study examining how symptoms of depression and cognitive function differ between people with MDD alone versus those with personality disorders.

How the Study Worked

The study took place in inpatient psychiatric units and included 60 patients who were admitted with symptoms of depression. Importantly, the researchers did not categorize patients into diagnostic groups right away. Instead, they assessed patients’ symptoms shortly after admission and again at discharge using several measures:

1. Clinician-rated depression severity (Hamilton Depression Rating Scale)
2. Self-reported depression severity (Beck Depression Inventory)
3. Overall illness severity (Clinical Global Impression scale)
4. Self-reported cognitive difficulties (Cognitive Failures Questionnaire)
5. Objective cognitive performance (Digit Symbol Substitution Test)

At discharge, patients underwent structured diagnostic interviews to determine their official diagnoses. Based on these results, the researchers divided participants into two main groups for analysis:

1. MDD-only group: 26 patients diagnosed with major depressive disorder or dysthymia
2. Personality disorder group: 27 patients diagnosed with one or more personality disorders (with or without co-occurring MDD)

Key Findings

The study revealed several important differences between the MDD-only and personality disorder groups:

Admission Symptom Ratings

• Clinician ratings: The MDD-only group was rated as having more severe depression by clinicians.
• Self-reports: The personality disorder group reported more severe depressive symptoms.

This discrepancy suggests that people with personality disorders may experience or communicate their distress differently than those with MDD alone. It’s possible that personality traits associated with some disorders (e.g., emotional intensity, interpersonal sensitivity) could lead to higher subjective ratings of depression.

Discharge Symptom Ratings

• Clinician ratings: Both groups showed similar levels of improvement, with no significant difference at discharge.
• Self-reports: The personality disorder group continued to report more severe depressive symptoms than the MDD-only group.

While both groups benefited from inpatient treatment, those with personality disorders still perceived their symptoms as more severe, even when clinicians observed similar improvements.

Cognitive Function

• Self-reported difficulties: The personality disorder group reported more cognitive problems both at admission and discharge.
• Objective performance: Both groups showed similar improvements on cognitive tests during their hospital stay.

This finding highlights another area where subjective experience and objective measures diverge for those with personality disorders. Despite measurable improvements in cognitive function, these individuals continued to perceive greater difficulties with memory, attention, and other cognitive processes.

What This Means for Patients and Families

These findings have several important implications for people experiencing depression, personality disorders, or both:

1. Subjective experience matters: While objective measures are important, a person’s own perception of their symptoms and functioning is crucial. For those with personality disorders, the subjective experience of depression may be more intense than outward appearances suggest.

2. Treatment can help both groups: Both MDD and personality disorder patients showed improvements during inpatient care. However, those with personality disorders may continue to struggle with their subjective experience of symptoms even as they improve objectively.

3. Cognitive complaints may persist: People with personality disorders may continue to report cognitive difficulties even when tests show improvement. This doesn’t mean the complaints aren’t real – it may reflect a heightened awareness of subtle cognitive changes or differences in how cognitive function is experienced.

4. Diagnosis is complex: The discrepancies between subjective and objective measures highlight the challenges in differentiating MDD from personality disorders. A thorough assessment considering multiple factors is crucial for accurate diagnosis.

5. Tailored treatment approaches: Understanding these differences can help clinicians develop more targeted treatment plans. For example, people with personality disorders may benefit from additional support in recognizing and internalizing their progress, or from therapies that address the subjective experience of symptoms.

Limitations and Future Directions

It’s important to note some limitations of this study. The sample size was relatively small, and the inpatient setting may not fully represent how these conditions present in outpatient or community settings. Additionally, the study focused on a specific set of measures and didn’t explore all possible aspects of depression or cognitive function.

Future research could expand on these findings by:

• Investigating a wider range of cognitive functions
• Following patients for longer periods after discharge
• Exploring how different types of personality disorders may influence these patterns
• Examining how these differences impact long-term treatment outcomes

Conclusions

• People with personality disorders tend to report more severe depressive symptoms and cognitive difficulties than those with MDD alone, even when objective measures show similar or lesser severity.
• Both groups can benefit from inpatient treatment, showing improvements in mood and cognitive function.
• The gap between subjective experience and objective measures in those with personality disorders persists even after treatment.
• Understanding these differences can help improve diagnosis, treatment planning, and support for people with depression, personality disorders, or both conditions.

By recognizing the complex interplay between depression and personality disorders, patients, families, and clinicians can work together to develop more personalized and effective approaches to mental health care.