People who first develop bipolar disorder at age 60 years or older are less ill overall than are those with the more typical pattern of early-onset bipolar disorder, said Martha Sajatovic, M.D., of the University Hospitals of Cleveland, and her associates.
The researchers used a large Veterans Affairs (VA) database to compare differences between early-onset and late-onset bipolar disorder in clinical presentation, use of health care services, and use of psychotropic medications over 2 years.
They identified 16,330 patients aged 60 years or older with bipolar disorder who were treated in 2001. These patients represented nearly one-fourth of all patients with bipolar disorder in the VA system at that time. Those who had their first diagnosis before 2001 were considered early-onset patients. Although late-onset has not been clearly defined, those whose first bipolar disorder diagnosis was made in 2001 and who were not diagnosed with psychosis or depression before that time were considered to have new-onset illness (NOI).
The great majority of these older patients with bipolar disorder (82.5%) had early-onset disease, whereas only 6.1% had NOI. The remaining patients either were new to the VA or had a questionable diagnosis and were excluded from the study.
Given that this was a sample of older veterans, it was a predominantly male and white population. The percentages of female and African American subjects were quite low, at 4.5% and 5.0% respectively, the investigators noted (Am. J. Geriatr. Psych. 2005;13:282–9).
Patients with early-onset bipolar disorder were hospitalized for mania much more often than those with NOI. They had a similar number of hospitalizations for depression, and a similar rate of homelessness and substance abuse. Those with early-onset bipolar disorder were more likely to be divorced or separated.
There was a substantial difference between the two groups in length of hospital stay. Total length of stay averaged 59.7 days for patients with early-onset bipolar disorder, compared with 43.5 days for those with NOI. The median duration of inpatient stay was 22 days for the early-onset bipolar disorder group, compared with 16 days for the NOI group.
Patients with early-onset bipolar disorder also used other health care services to a much greater degree than did those with NOI. In particular, they showed “substantial utilization of inpatient nonpsychiatric care,” the researchers noted.
Those with early-onset bipolar disorder also were much more likely to be treated with lithium or any mood stabilizer than were patients with NOI. (See box.) Those with early-onset bipolar disorder also were much more likely to receive an atypical antipsychotic compound. Thus, older individuals with early-onset bipolar disorder appear to be generally more severely ill than their late-onset counterparts, Dr. Sajatovic and her associates said.
These findings suggest that “these are indeed two separate subgroups of older adults with bipolar disorder,” the investigators said.
“Previous investigators have noted that late-onset bipolar illness is characterized by neurological comorbidity, absence of a family history, and a greater likelihood of psychotic presentation,” Dr. Sajatovic and her associates noted. Various researchers have linked late-onset bipolar disorder with organic cerebral disorders and with cerebrovascular risk factors, such as smoking, hypertension, diabetes, and coronary disease.
In this study, patients with NOI were nearly twice as likely to receive a diagnosis of “type II/not otherwise specified bipolar illness.”
This increased prevalence might be explained by aging-related vascular and CNS pathology in such patients. “It has been suggested that late-onset bipolar disorder is associated with peripheral vascular burden and vascular brain abnormalities,” the investigators said.
They also noted that in this study, fewer than two-thirds of the patients with early-onset bipolar disorder–and just 30% of those with NOI–were receiving mood stabilizers, which “is at odds with current treatment guidelines for bipolar disorder in adults.”
It may be that treatments “known to be efficacious and well tolerated in younger bipolar populations” do not work as well in geriatric bipolar patients. Moreover, in older patients, “first-line treatments have not been definitively established,” Dr. Sajatovic and her associates said.
RICHARD FRANKI, RESEARCH