Missing mother Nicola Bulley had “significant issues” with alcohol brought on by her ongoing struggles with the menopause, police have said.
The 45-year-old went missing on 27 January during a riverside dog walk in St Michael’s on Wyre.
Officers said Ms Bulley had been considered a high-risk missing person from the start of the investigation.
Lancashire Police said it was called to a concern for welfare report at her home last month.
Health professionals also attended on 10 January, the force said, adding no arrests were made but it was being investigated.
A police spokesman said it was clear after speaking to Ms Bulley’s family she had “in the past suffered with some significant issues with alcohol which were brought on by her ongoing struggles with the menopause”.
“These struggles had resurfaced over recent months [and] this caused some real challenges for [her partner] Paul and the family,” the spokesman added.
The force said it had taken the “unusual step” to go into this level of detail as it was “important to clarify what we meant when we talked about vulnerabilities to avoid any further speculation or misinterpretation”.
“We have explained to Nicola’s family why we have released this further information and we would ask that their privacy is respected at this difficult time.”
The police have been criticised by some on social media for disclosing such personal information about a victim.
Zoe Billingham, formerly a lead inspector for the police watchdog HMICFRS, tweeted that she was “deeply troubled” by its release at this stage.
“I have to wonder if some in Lancashire Police are placing the protection of their reputation above their focus on finding Nicola,” she added.
Ms Bulley disappeared while walking her springer spaniel, Willow, after dropping off her two daughters – aged six and nine – at school.
Lancashire Police first told the public of their “main working hypothesis” on 3 February, that the mortgage adviser had gone into the river during a “10-minute window” between 09:10 GMT and 09:20 that day.
Detectives have since extended the search to the sea, saying finding her there “becomes more of a possibility”.
In a press conference earlier, Det Supt Smith, who is the lead investigator in the case, confirmed there was still no evidence of a criminal aspect or third-party involvement.
Ms Bulley’s partner, Paul Ansell, has previously said he was 100% convinced she did not fall into the water.
But Det Supt Smith said their main theory was still that Ms Bulley had “unfortunately gone in the river”.
However, she said she could not be “100% certain of that at the minute” as it was a “live investigation” and there was “always information coming in”.
She said other hypotheses remained in place and were “reviewed regularly”.
Nearly 40 detectives have since sifted through hundreds of hours of CCTV, dashcam footage and tip-offs from the public.
Det Supt Smith said the force had also been “inundated with false information, accusations and rumours which is distracting”.
She said in her 29 years of police service she had not seen “anything like it” and described “persistent myths” about the case.
“The derelict house which is across the other side of the river has been searched three times, with the permission of the owner, and Nicola is not in there,” she said.
She added reports of a red van in the area on the morning of Ms Bulley’s disappearance were not being treated as suspicious.
The detective also confirmed a glove found near where she disappeared did not belong to Ms Bulley.
Assistant Chief Constable Peter Lawson defended his force’s investigation into the case of the missing mother.
He said the force had decided to share more details “than would normally be the case” to counter some of “the ill-informed speculation and conjecture”.
“It has been a distraction that is potentially damaging to the investigation, the community of St Michael’s and most importantly Nicola’s family,” he said.
On Tuesday the Lancashire force said it had arrested two people after malicious messages were sent to a number of parish councillors about the case.