Normal pressure hydrocephalus due to idiopathic aqueductal stenosis is an abnormal accumulation of CSF in the cerebral ventricles caused by an obstruction in the Sylvian aqueduct. Although NPH typically presents with the progressive ‘triad’ of cognitive impairment, gait disturbance and urinary incontinence it has been described that it rarely manifests with predominant psychotic symptoms.

A clinical case was followed and reviewed to illustrate the psychiatric symptoms in NPH.

A 32-year-old female was admitted to our acute psychiatric department because she exhibited verbal and physical aggressive behavior while being in an agitated state with persecutory delusions. Symptoms appeared and gradually exacerbated over a 5-year period reaching their climax two weeks before admission. The patient's increased body weight and bradykinetic appearance implied the presence of an underlying organic factor. However her endocrinological workup proved normal and her neurological examination revealed no actual focal deficits. An EEG also proved negative for seizure activity and encephalopathy.

Neuropsychological batteries showed mild cognitive impairment and a CT scan revealed considerable dilatation of the ventricular system due to idiopathic aqueductal stenosis. While a conservative approach was chosen for the treatment of NPH our patient was initiated on atypical antipsychotics showing marked improvement of her psychiatric symptomatology.

Patients without a prior psychiatric history who have soft nonlocalising neurological signs and mild cognitive deficits in association with prominent psychotic symptomatology should raise our index of suspicion and prompt the clinician to explore the existence of an organic factor contributing to a behavioral disorder.