Bipolar Disorders: Mixed States, Rapid-Cycling, and Atypical Forms

257 Atypical features of bipolarity in old ageNosologic confusionDepending on whether one is conversant with the neurological or psychiatricliterature, terms such as ‘‘disinhibition syndrome’’ may be replaced with theconcept of ‘‘secondary mania.’’ The actual description of these two syndromeshowever is virtually identical (Shulman, 1997). In particular, it is the high rate ofneurologic comorbidity that causes difficulty for categorization of the heterogeneousmanic syndromes seen in old age. For example, the Diagnostic andStatistical Manual of Mental Disorders, 4th edn (DSM-IV: American PsychiatricAssociation, 1994) established a category of ‘‘mood disorder due to a generalmedical condition’’ (293.83) indicating that ‘‘the disturbance is the direct physiologicconsequence of a general medical condition.’’ However, in an elderly subpopulation,even when there is a close temporal association, it is difficult todetermine whether the medical or neurological comorbidity is a ‘‘direct physiologicconsequence,’’ simply an associated finding, or just a precipitant. Thus, theassumption of an etiological relationship is highly questionable.Krauthammer and Klerman (1978) proposed the notion of secondary maniaand posit a close temporal relationship between the medical/neurological conditionand the manic syndrome. They stipulated that there should be no familyhistory and no prior history of mood disorder and took pains to distinguishsecondary mania from the syndrome of delirium.Most recently, investigators have proposed a concept of vascular mood disorderincluding both vascular depression and vascular mania (Krishnan and McDonald,1995; Alexopoulos et al., 1997; Steffens and Krishnan, 1998). The original notionof ‘vascular depression’ rests on a number of clinical observations and imagingfindings, including a higher prevalence of cognitive dysfunction, increased cerebralatrophy and hyperintensities in late-onset depression (Alexopoulos et al.,1997). This subtype of depression was also associated with greater functionaldisability, higher morbidity and mortality, as well as a lower genetic predispositioncompared to early-onset patients. Using a similar template, Steffens and Krishnan(1998) detailed the criteria for a vascular mania subtype (Table 11.1).Proposed subtypesBased on the available literature, Shulman and Herrmann (2002) have proposedfour subtypes that may have heuristic value for further research.(1) Primary bipolar disorder: this subtype should be used for those early-onsetpatients who continue to show mood disorder into old age. Despite the factthat relatively few of these individuals appear in studies of hospitalized elderlybipolar patients, it is likely that community and outpatient samples of elderlybipolar patients will reveal a higher proportion of the subtype.