Neuropsychiatry of corticobasal degeneration and progressive supranuclear palsy

Corticobasal syndrome (CBS) and progressive supranuclear palsy syndrome (PSPS) are two of the atypical Parkinsonism syndromes, in that patients exhibit rigidity, occasional tremor and postural instability, but do not symptomatically respond to dopamine replacement. CBS and PSPS can often present with complex cognitive difficulties and neuropsychiatric disturbances. Symptoms of depression, apathy, or agitation can be subtle and are often overlooked as reactions to learning a new diagnosis of Parkinsonism. These symptoms may be the earliest presenting evidence of CBS or PSPS, and these syndromes can be misdiagnosed with a primary psychiatric disorder rather than a neurodegenerative condition. Patients may be inappropriately treated with antipsychotic medications that exacerbate the extra-pyramidal motor features of the syndromes. When symptoms are considered to comprise a neurodegenerative syndrome, it may be an inaccurate diagnosis as many features of CBS and PSPS not only overlap with each other, but also with other dementia syndromes. This review discusses similarities and differences between the syndromes of CBS and PSPS in terms of neuropsychiatric features. Improved characterization of the clinical syndromes is necessary to better predict underlying pathology. Improved education about these diseases would help patients, caregivers and clinicians to anticipate symptom progression and avoid premature nursing home placement.