# Loneliness and Its Associations With Personality Functioning: Evidence From Longitudinal Inpatient Psychotherapy Programs in Germany

## TL;DR

This study shows that loneliness is linked to personality functioning in individuals with personality disorders and that psychotherapy can improve both.

## Contribution

The study provides new longitudinal evidence on the relationship between loneliness and personality functioning in inpatient psychotherapy.

## Key findings

- Baseline loneliness was associated with self-direction and intimacy in personality functioning.
- Changes in loneliness correlated with changes in identity and intimacy during treatment.
- Psychotherapy reduced loneliness and improved self-functioning in personality disorders.

## Abstract

Loneliness is an aversive state that occurs at elevated rates among individuals with mental health disorders and may reciprocally exacerbate psychopathological processes. Individuals with personality disorders (PDs) appear particularly susceptible; however, knowledge regarding the relationship between loneliness and facets of personality functioning (PF) remains limited. Greater conceptual and empirical clarity is needed to elucidate the mechanisms linking loneliness with maladaptive self‐ and interpersonal functioning and to inform clinical practice. We examined the association between loneliness and PF in a longitudinal cohort of 87 inpatients undergoing psychotherapy programs. Loneliness was measured with the UCLA Loneliness Scale. PF was evaluated with the Semi‐Structured Interview for Personality Functioning and the Level of Personality Functioning Scale. Baseline loneliness scores were positively associated with self‐direction and intimacy, and changes in loneliness were correlated with changes in identity and intimacy. During treatment, significant changes were observed for loneliness and PF, particularly self‐functioning, based on self‐ and clinician ratings. These findings indicate that loneliness is associated with dimensions of self‐ and interpersonal functioning cross‐sectionally and longitudinally. Larger longitudinal studies are needed to elucidate how components of loneliness and PF are interconnected and to identify underlying mechanisms that may inform interventions aimed at reducing loneliness in individuals with PDs.

Loneliness is prevalent in personality disorders (PDs) and linked to impairments in personality functioning (PF). Loneliness was cross‐sectionally associated with PF domains (self‐direction, intimacy), and with changes in PF (identity, intimacy). Ten weeks of psychotherapy significantly reduced loneliness and improved PF, especially self‐functioning. Our findings suggest that loneliness and PF are intertwined, changing concurrently during psychotherapy. Larger longitudinal studies may clarify mechanisms and inform interventions to reduce loneliness in PDs.