The hospital saw an 11% jump in attendances in the 60- to 74-year age range in the first 13 weeks of this year, Southern District Health Board figures show.
Admissions to hospital rose 4% in this age range, compared with the same period last year.
In those aged 75 and over, there was a 1% rise in attendances and 3% more were admitted to hospital.
Demand was up across all age groups and 7% more attendances resulted in 14% more admissions.
DHB systems improvement manager Allan Cumming said there were "many theories" circulating about the rise in demand, which continued to be felt.
Warmer-than-usual weather could account for more young people and the Christchurch earthquakes could be a factor across all age groups.
The increase in older people presented an additional load, because they took longer to treat.
If not for improvements under the "Six Hours - It Matters!" project, he believed the department would not be coping.
"At least the department is not as stressed, not as chaotic as it was a year ago."
The DHB was still working on how to get patients through ED more quickly.
The department was averaging about 85% of patients treated or transferred within six hours (the target is 95%).
The observation ward opening in a couple of months would help, as would improving admission and discharge procedures.
DHB Otago chief operating officer Vivian Blake said the DHB was yet to appoint a new clinical leader to the department after Dr Tim Kerruish stepped down in March, in frustration at lack of staffing.
" In the meantime, good progress is being made in determining the optimum ED staffing levels at both Dunedin and Southland Hospitals, including better alignment with peak attendance times," she said.
Grey Power Otago president Jo Millar said she believed cost was putting some older people off going to the doctor.
"I honestly believe that some just can't afford [the GP] now."
It could account for increased demand in ED.
The rise in admissions suggested people were becoming very ill before receiving medical attention, she said.
Mrs Millar was seeking more information from the National Health Board on GP charge rates for those over 65 years.
Some Dunedin GPs charge the same rate for those aged 65 and over as for younger people, while others had a discount rate.
The $2 prescription price rise in the Budget would put further pressure on older people already hurting from inexorable cost-of-living increases, she said.
Mornington Health Centre chronic care nurse Anna Askerud had noticed an increase this year in older people seeking access to the PHO's Care Plus programme, which made GP visits much cheaper.
To be eligible, people need to have two chronic conditions.
She believed the programme was not well used by some Dunedin GP practices, as it was considered cumbersome to administer.
Southern DHB board member Dr Branko Sijnja said the emergency department should be a "referred service", like other hospital specialties.
Apart from emergencies, which would naturally go straight to ED, Dr Sijnja believed patients should first see an on-site GP.
The GP, who would act as a "sorting gate", would be especially useful for older patients, who often had chronic conditions usually dealt with in primary care.
