Patients with Alzheimer's disease (AD) have heterogeneous rates of disease progression. The aim of the current study is to investigate whether neuropsychiatric disturbances predict cognitive and functional disease progression in AD, according to failure theory. We longitudinally examined 177 memory-clinic AD outpatients (mean age = 73.1, SD = 8.1; 70.6% women). Neuropsychiatric disturbances at baseline were categorized into five syndromes. Patients were followed for up to two years to detect rapid disease progression defined as a loss of ≥ 1 abilities in Activities of Daily living (ADL) or a drop of ≥ 5 points on Mini-Mental State Examination (MMSE). Hazard ratios (HR) were calculated with Gompertz regression, adjusting for sociodemographics, baseline cognitive and functional status, and somatic comorbidities. Most patients (74.6%) exhibited one or more neuropsychiatric syndromes at baseline. The most common neuropsychiatric syndrome was Apathy (63.8%), followed by Affective (37.3%), Psychomotor (8.5%), Manic (7.9%), and Psychotic (5.6%) syndromes. The variance between the observed (Kaplen Meier) and predicted (Gompertz) decline for disease progression in cognition (0.30, CI = 0.26–0.35), was higher than the variance seen for functional decline (0.22, CI = 0.18–0.26). After multiple adjustment, patients with the Affective syndrome had an increased risk of functional decline (HR = 2.0; CI = 1.1–3.6), whereas the risk of cognitive decline was associated with the Manic (HR = 3.2, CI = 1.3–7.5) syndrome. In conclusion, specific neuropsychiatric syndromes are associated with functional and cognitive decline during the progression of AD, which may help with the long-term planning of care and treatment. These results highlight the importance of incorporating a thorough psychiatric examination in the evaluation of AD patients.