Mild Behavioral impairment (MBI) and late-life psychiatric disorders: Differential clinical features and outcomes.

Abstract

Mild Behavioral Impairment (MBI) refers to a late-onset neurobehavioral syndrome in which neuropsychiatric symptoms (NPS) represent early markers of dementia. Though being a promising diagnostic category for neurobiological research, in daily clinical practice, the boundaries and relationships between MBI and late-life psychiatric disorders are yet to be established. Particularly, no studies have been conducted so far on the prognostic implications of an MBI diagnosis in the psychogeriatric context.

For these reasons, since June 2020, we are conducting a prospective longitudinal study on MBI in psychogeriatric patients. On June 2022, 144 elderly patients (≥50 years) referred to the outpatient clinic of the 2nd Psychiatric Unit of the University of Pisa had been recruited. Patients had been diagnosed with a primary psychiatric disorder (N=73, 50.6%), MBI (N=40, 27.8%) or dementia (N=31, 21.5%). Patients with MBI showed a significantly higher age at onset of psychiatric disorders and depressive episodes than patients diagnosed with primary psychiatric disorders. MCI and vascular leukoencephalopathy were also more common in patients with MBI. Moreover, compared to primary psychiatric disorders, MBI was associated with a significantly higher psychopathology severity, especially in the apathy and negative symptoms domain.

Preliminary longitudinal analyses were also performed on a subsample of 83 patients followed-up for at least 3 months (on average for one year): at baseline 44 patients had been diagnosed with primary mood disorders including 23 patients in remission and 21 patients with current mood episodes; 22 patients had MBI and 17 were diagnosed with dementia. While at follow-up patients with mood episodes showed a significant decrease in psychopathology severity and increase in global functioning, those with MBI had no significant improvements.

In conclusion, MBI is a common condition in psychogeriatric settings and shows distinctive clinical features that may help differential diagnosis. Moreover, the presence of MBI in patients with late-life psychiatric disorders may affect both clinical and functional outcomes. The recognition of patients with MBI symptoms, including apathy, might be useful for the early detection of individuals with poor prognosis.