In this chapter, we report empirical findings from the Berlin Aging Study (BASE) on the types and frequencies of psychiatric illnesses in old age, their somatic and social predictors, and their consequences.

Nearly half (44%) of the West Berliners aged 70 and above had no psychiatric disorders, whereas less than a quarter (24%) were clearly psychiatrically ill (specified DSM-III-R diagnoses). The remaining third consisted of carriers of psychopathological symptoms without illness value (16%) and of psychiatric syndromes with illness value (17%). Because this last group (mainly affective disorders) differs from the psychiatrically healthy in indicators of health impairment (in prognosis and use of psychotropic drugs), despite not fulfilling the criteria of operationalized DSM-III-R diagnoses, we speak of “subdiagnostic psychiatric morbidity.” In further analyses we tried to determine the thresholds defining gradations from mental health to subdiagnostic psychiatric morbidity. Thus, with the help of a consensus conference between internists and psychiatrists, which was specifically developed for the purpose of BASE, we have demonstrated that in the case of depression, scores on the Hamilton Depression Scale (HAMD) are half as great when cases that are probably of somatic origin are excluded.

The most frequent psychiatric illness in old age is dementia, affecting 14% of those aged 70 years and above. Recalculated for the population of over-65-year-olds, this corresponds to a prevalence of 6% (excluding mild forms). The number of dementia cases increases strongly with age. […]